U.S. patent application number 13/316755 was filed with the patent office on 2013-06-13 for glaucoma drainage devices including vario-stable valves and associated systems and methods.
The applicant listed for this patent is Sebastian Bohm, Leslie A. Field, Matthew J.A. Rickard. Invention is credited to Sebastian Bohm, Leslie A. Field, Matthew J.A. Rickard.
Application Number | 20130150777 13/316755 |
Document ID | / |
Family ID | 47470203 |
Filed Date | 2013-06-13 |
United States Patent
Application |
20130150777 |
Kind Code |
A1 |
Bohm; Sebastian ; et
al. |
June 13, 2013 |
Glaucoma Drainage Devices Including Vario-Stable Valves and
Associated Systems and Methods
Abstract
Glaucoma drainage devices including vario-stable valves and
associated systems and methods are disclosed. A glaucoma drainage
device includes a drainage lumen and a valve system coupled to the
drainage lumen to control the flow of fluid through the drainage
lumen. The valve system includes an adjustable valve with a
diaphragm that is in communication with the drainage lumen and is
movable to occupy varying amounts of the drainage lumen. In some
embodiments, the valve system is maintained in a desired position
without the use of power such that power is only needed when
changing a position of the adjustable valve.
Inventors: |
Bohm; Sebastian; (San Diego,
CA) ; Field; Leslie A.; (Portola Valley, CA) ;
Rickard; Matthew J.A.; (Yorba Linda, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bohm; Sebastian
Field; Leslie A.
Rickard; Matthew J.A. |
San Diego
Portola Valley
Yorba Linda |
CA
CA
CA |
US
US
US |
|
|
Family ID: |
47470203 |
Appl. No.: |
13/316755 |
Filed: |
December 12, 2011 |
Current U.S.
Class: |
604/9 |
Current CPC
Class: |
A61B 3/16 20130101; A61F
9/00781 20130101 |
Class at
Publication: |
604/9 |
International
Class: |
A61F 9/00 20060101
A61F009/00 |
Claims
1. A glaucoma drainage device comprising: a drainage lumen; a valve
system coupled to the drainage lumen, the valve system including:
an adjustable valve having: a housing defining a cavity; and a
diaphragm bounding at least one side of the cavity, the diaphragm
in communication with the drainage lumen, the diaphragm movable
between a first position that occupies a first amount of the
drainage lumen and a second position that occupies a second amount
of the drainage lumen, the second amount being greater than the
first amount; and a fluid reservoir in fluid communication with the
cavity of the adjustable valve; a first check valve positioned
between the fluid reservoir and the cavity of the adjustable valve
along a first fluid passageway, the first check valve preventing
fluid flow from the fluid reservoir to the cavity of the adjustable
valve; and a second check valve positioned between the fluid
reservoir and the cavity of the adjustable valve along a second
fluid passageway, the second check valve preventing fluid flow from
the cavity of the adjustable valve to the fluid reservoir.
2. The glaucoma drainage device of claim 1, wherein the valve
system further includes an actuator for controlling a flow of fluid
between the fluid reservoir and the cavity of the adjustable
valve.
3. The glaucoma drainage device of claim 2, wherein the actuator
comprises a voltage source and a plurality of electrodes.
4. The glaucoma drainage device of claim 3, wherein the plurality
of electrodes consists of two electrodes.
5. The glaucoma drainage device of claim 3, wherein the actuator
comprises an actuator fluid and a bubble-generating system
configured to generate bubbles by converting at least a portion of
the actuator fluid to a gas.
6. The glaucoma drainage device of claim 5, wherein the pair of
electrodes are positioned within the fluid reservoir.
7. The glaucoma drainage device of claim 3, wherein one of the two
electrodes is positioned within the fluid reservoir and the other
of the two electrodes is positioned outside of the fluid
reservoir.
8. The glaucoma drainage device of claim 7, wherein the other of
the two electrodes is positioned within the cavity of the
adjustable valve.
9. The glaucoma drainage device of claim 3, wherein the fluid
reservoir is formed of a material that defines a constant volume
cavity during operation.
10. The glaucoma drainage device of claim 3, wherein the fluid
reservoir is formed of a flexible material that defines a variable
volume cavity during operation.
11. The glaucoma drainage device of claim 10, further comprising:
an electro-kinetic membrane positioned between the fluid reservoir
and the cavity of the adjustable valve.
12. The glaucoma drainage device of claim 11, wherein an
electro-kinetic fluid is received within the fluid reservoir and
the cavity of the adjustable valve.
13. The glaucoma drainage device of claim 2, further comprising:
first pressure sensor configured for positioning in fluid
communication with an anterior chamber of an eye; and a second
pressure sensor configured for positioning in fluid communication
with a drainage location; wherein readings from the first pressure
sensor and the second pressure sensor are utilized to control the
actuator.
14. The glaucoma drainage device of claim 13, further comprising: a
processor in communication with the first and second pressure
sensors and the actuator.
15. The glaucoma drainage device of claim 2, further comprising: a
first pressure sensor configured for positioning in fluid
communication with an anterior chamber of an eye; and a second
pressure sensor configured for positioning remote from the first
pressure sensor such that the second pressure sensor measures or
approximates atmospheric pressure; wherein readings from the first
pressure sensor and the second pressure sensor are utilized to
control the actuator
16. The glaucoma drainage device of claim 15, further comprising: a
processor in communication with the first and second pressure
sensors and the actuator.
17. The glaucoma drainage device of claim 15, wherein the second
pressure sensor is sized and shaped for positioning in a
subconjunctival space of the eye.
18. The glaucoma drainage device of claim 2, further comprising: a
first pressure sensor configured for positioning in fluid
communication with a drainage location; and a second pressure
sensor configured for positioning remote from the first pressure
sensor such that the second pressure sensor measures or
approximates atmospheric pressure; wherein readings from the first
pressure sensor and the second pressure sensor are utilized to
control the actuator.
19. The glaucoma drainage device of claim 18, further comprising: a
processor in communication with the first and remote pressure
sensors and the actuator.
20. The glaucoma drainage device of claim 18, wherein the second
pressure sensor is sized and shaped for positioning in a
subconjunctival space of the eye.
21. The glaucoma drainage device of claim 1, wherein the adjustable
valve is arranged as a boss valve.
22. The valve system of claim 1, wherein at least one of the first
and second check valves is a converging pathway.
23. The valve system of claim 1, wherein at least one of the first
and second check valves is a diverging pathway.
24. The valve system of claim 1, wherein the valve system is
configured to maintain the diaphragm in a desired position after
actuation of an actuator configured to move the diaphragm between
the first and second positions has ceased.
25. The valve system of claim 1, wherein the drainage lumen and
valve system are configured to pump aqueous humor from an anterior
chamber of an eye.
26. The valve system of claim 25, wherein the valve system is
configured to be activated when in the vicinity of an external
power source and deactivated when not in the vicinity of an
external power source.
27. A method of controlling intraocular pressure of an eye of a
patient, the method comprising: obtaining pressure readings from a
plurality of pressure sensors; determining a desired position of a
diaphragm of an adjustable valve based on the obtained pressure
readings; actuating an actuator to cause a flow of fluid between a
cavity of the adjustable valve and a fluid reservoir to adjust the
position of the diaphragm to the desired position; and ceasing
actuation of the actuator, wherein the diaphragm is maintained in
the desired position after actuation of the actuator has
ceased.
28. The method of claim 27, wherein the diaphragm is maintained in
the desired position after actuation of the actuator has ceased by
a pair of opposing check valves positioned between the cavity of
the adjustable valve and the fluid reservoir.
29. The method of claim 27, wherein the obtained pressure readings
include at least one of the pressure readings selected from the
group consisting of: a pressure within an anterior chamber of an
eye; a pressure within a drainage location spaced from the anterior
chamber of the eye; and an atmospheric pressure.
30. The method of claim 29, wherein the at least one of pressure
readings includes the atmospheric pressure and wherein the
atmospheric pressure is obtained from a pressure sensor located in
a subconjunctival area of the eye.
31. The method of claim 27, wherein the desired position is any
position within a subset of positions of a full range of positions
of the diaphragm, the subset of positions defining a desired range
of positions for the diaphragm based on the obtained pressure
readings.
32. The method of claim 27, wherein the desired position is a
specific position within the full range of positions of the
diaphragm.
Description
BACKGROUND
[0001] The present disclosure relates generally to valves and
associated systems and methods for use in ophthalmic treatments. In
some instances, embodiments of the present disclosure are
configured to be part of an IOP control system.
[0002] Glaucoma, a group of eye diseases affecting the retina and
optic nerve, is one of the leading causes of blindness worldwide.
Most forms of glaucoma result when the intraocular pressure (IOP)
increases to pressures above normal for prolonged periods of time.
IOP can increase due to high resistance to the drainage of the
aqueous humor relative to its production. Left untreated, an
elevated IOP causes irreversible damage to the optic nerve and
retinal fibers resulting in a progressive, permanent loss of
vision.
[0003] The eye's ciliary body continuously produces aqueous humor,
the clear fluid that fills the anterior segment of the eye (the
space between the cornea and lens). The aqueous humor flows out of
the anterior chamber (the space between the cornea and iris)
through the trabecular meshwork and the uveoscleral pathways, both
of which contribute to the aqueous drainage system. The delicate
balance between the production and drainage of aqueous humor
determines the eye's IOP.
[0004] FIG. 1 is a diagram of the front portion of an eye that
helps to explain the processes of glaucoma. In FIG. 1,
representations of the lens 110, cornea 120, iris 130, ciliary body
140, trabecular meshwork 150, and Schlemm's canal 160 are pictured.
Anatomically, the anterior segment of the eye includes the
structures that cause elevated IOP which may lead to glaucoma.
Aqueous fluid is produced by the ciliary body 140 that lies beneath
the iris 130 and adjacent to the lens 110 in the anterior segment
of the eye. This aqueous humor washes over the lens 110 and iris
130 and flows to the drainage system located in the angle of the
anterior chamber. The angle of the anterior chamber, which extends
circumferentially around the eye, contains structures that allow
the aqueous humor to drain. The trabecular meshwork 150 is commonly
implicated in glaucoma. The trabecular meshwork 150 extends
circumferentially around the anterior chamber. The trabecular
meshwork 150 seems to act as a filter, limiting the outflow of
aqueous humor and providing a back pressure that directly relates
to IOP. Schlemm's canal 160 is located beyond the trabecular
meshwork 150. Schlemm's canal 160 is fluidically coupled to
collector channels (not shown) allowing aqueous humor to flow out
of the anterior chamber. The two arrows in the anterior segment of
FIG. 1 show the flow of aqueous humor from the ciliary bodies 140,
over the lens 110, over the iris 130, through the trabecular
meshwork 150, and into Schlemm's canal 160 and its collector
channels.
[0005] One method of treating glaucoma includes implanting a
drainage device in a patient's eye. The drainage device allows
fluid to flow from the interior chamber of the eye to a drainage
site, relieving pressure in the eye and thus lowering IOP. These
devices are generally passive devices and do not provide a smart,
interactive control of the amount of flow through the drainage
tube. In addition, fluid filled blebs frequently develop at the
drainage site. The development of the bleb typically includes
fibrosis, which leads to increased flow resistance and it is
generally the case that this resistance increases overtime. This
development and progression of fibrosis reduces or eliminates flow
from the anterior chamber, eliminating the capacity of the drainage
device to affect IOP.
[0006] The system and methods disclosed herein overcome one or more
of the deficiencies of the prior art.
SUMMARY
[0007] In one embodiment consistent with the principles of the
present disclosure, a glaucoma drainage device is provided. The
glaucoma drainage device includes a drainage lumen and a valve
system coupled to the drainage lumen and optional pump. The valve
system includes an adjustable valve. In some instances the
adjustable valve is arranged as a boss valve, which includes a
portion with a raised, thicker, and/or stiffer bossed area in some
instances. The adjustable valve has a housing defining a cavity and
a diaphragm bounding at least one side of the cavity. The diaphragm
is in communication with the drainage lumen and is movable between
a first position that occupies a first amount of the drainage lumen
and a second position that occupies a second amount of the drainage
lumen, where the second amount is greater than the first amount. A
fluid reservoir is in fluid communication with the cavity of the
adjustable valve. In that regard, a first check valve is positioned
between the fluid reservoir and the cavity of the adjustable valve
along a first fluid passageway. The first check valve prevents
fluid flow from the fluid reservoir to the cavity of the adjustable
valve. Further, a second check valve is positioned between the
fluid reservoir and the cavity of the adjustable valve along a
second fluid passageway. The second check valve prevents fluid flow
from the cavity of the adjustable valve to the fluid reservoir.
[0008] In some instances, the valve system further includes an
actuator for controlling a flow of fluid between the fluid
reservoir and the cavity of the adjustable valve. In that regard,
the actuator is a voltage source and a pair of electrodes in some
embodiments. The pair of electrodes is positioned within the fluid
reservoir in some instances. In other instances, one of the
electrodes is positioned within the fluid reservoir and the other
electrode is positioned outside of the fluid reservoir. In one
specific instance, the second electrode is positioned within the
cavity of the adjustable valve.
[0009] In some configurations, the valve system also includes a
first adjustable component positioned adjacent the first fluid
passageway such that a diaphragm of the first adjustable component
is movable between a first position that occupies a first amount of
the first fluid passageway and a second position that occupies a
second amount of the first fluid passageway, where the second
amount is greater than the first amount. Further, in some
embodiments, the valve system further includes a second adjustable
component positioned adjacent the second fluid passageway such that
a diaphragm of the second adjustable component is movable between a
first position that occupies a first amount of the second fluid
passageway and a second position that occupies a second amount of
the second fluid passageway, where the second amount is greater
than the first amount. The adjustable components are bubble
chambers in some implementations.
[0010] The glaucoma drainage device also includes associated
pressures in some embodiments. In one embodiment, a first pressure
sensor is configured for positioning in fluid communication with an
anterior chamber of an eye and a second pressure sensor is
configured for positioning in fluid communication with a drainage
location. Readings from the first and second pressure sensors are
utilized to control the actuator. In that regard, in some instances
the glaucoma drainage device includes a processor in communication
with the first and second pressure sensors and the actuator that
processes data received from the pressure sensors to control the
actuator. In some embodiments, the glaucoma drainage device
includes a third pressure sensor configured for positioning within
a subconjunctival space of the eye such that the third pressure
sensor provides an indication of atmospheric pressure. In that
regard, readings from any combination of the first, second, and
third pressure sensors may be utilized to control the actuator.
Note that the difference between the anterior chamber pressure
sensor and the atmospheric reference pressure sensor will provide
an TOP measurement that may be used for adjusting the actuator.
Similarly, the difference between the absolute drainage site
pressure and the atmospheric reference pressure will provide a true
(gauge) reading of the drainage site pressure.
[0011] In some instances, the fluid reservoir is formed of a
material that defines a constant volume cavity during operation. In
other instances, the fluid reservoir is formed of a flexible
material that defines a variable volume cavity during operation. In
some embodiments, an electro-kinetic membrane is positioned between
the fluid reservoir and the cavity of the adjustable valve. In such
embodiments, an electro-kinetic fluid is received within the fluid
reservoir and the cavity of the adjustable valve. In that regard,
to control the flow of electro-kinetic fluid, one of the pair of
electrodes is positioned on opposite sides of the membrane thereby
inducing a controllable, electro-osmotic pressure gradient. In a
different embodiment, the actuator comprises an actuator fluid and
a bubble-generating system configured to generate bubbles by
converting at least a portion of the actuator fluid to a gas.
[0012] In another embodiment consistent with the principles of the
present disclosure, a valve system for use within an
ophthalmological device is provided. The valve system includes an
adjustable valve having a housing defining a cavity and a movable
diaphragm bounding at least one side of the cavity. In some
instances, the adjustable valve is arranged as a boss valve, which
includes a portion with a raised, thicker, and/or stiffer bossed
area in some instances. The valve system also includes a fluid
reservoir in fluid communication with the cavity of the adjustable
valve. A first check valve is positioned between the fluid
reservoir and the cavity of the adjustable valve along a first
fluid passageway. The first check valve prevents fluid flow from
the fluid reservoir to the cavity of the adjustable valve. A second
check valve is positioned between the fluid reservoir and the
cavity of the adjustable valve along a second fluid passageway. The
second check valve prevents fluid flow from the cavity of the
adjustable valve to the fluid reservoir.
[0013] In some instances, the valve system further includes an
actuator for controlling a flow of fluid between the fluid
reservoir and the cavity of the adjustable valve. In that regard,
the actuator is a voltage source and a pair of electrodes in some
embodiments. The electrodes are positioned within the fluid
reservoir in some instances. In other instances, one of the
electrodes is positioned within the fluid reservoir and the other
electrode is positioned outside of the fluid reservoir. In one
specific instance, the second electrode is positioned within the
cavity of the adjustable valve.
[0014] In some instances, the fluid reservoir is formed of a
material that defines a constant volume cavity during operation. In
other instances, the fluid reservoir is formed of a flexible
material that defines a variable volume cavity during operation. In
some embodiments, an electro-kinetic membrane is positioned between
the fluid reservoir and the cavity of the adjustable valve. In such
embodiments, an electro-kinetic fluid is received within the fluid
reservoir and the cavity of the adjustable valve. In that regard,
to control the flow of electro-kinetic fluid one of the electrodes
is positioned on opposite sides of the membrane thereby inducing a
controllable electro-osmotic pressure gradient. In a different
embodiment, the actuator comprises an actuator fluid and a
bubble-generating system configured to generate bubbles by
converting at least a portion of the actuator fluid to a gas.
[0015] In some configurations, the valve system also includes a
first adjustable component positioned adjacent the first fluid
passageway such that a diaphragm of the first adjustable component
is movable between a first position that occupies a first amount of
the first fluid passageway and a second position that occupies a
second amount of the first fluid passageway, where the second
amount is greater than the first amount. Further, in some
embodiments, the valve system further includes a second adjustable
component positioned adjacent the second fluid passageway such that
a diaphragm of the second adjustable component is movable between a
first position that occupies a first amount of the second fluid
passageway and a second position that occupies a second amount of
the second fluid passageway, where the second amount is greater
than the first amount. The adjustable components are bubble
chambers in some implementations.
[0016] In another embodiment consistent with the principles of the
present disclosure, a method is provided. The method includes:
obtaining pressure readings from a plurality of pressure sensors,
determining a desired position of a diaphragm of an adjustable
valve based on the obtained pressure readings; actuating an
actuator to cause a flow of fluid between a cavity of the
adjustable valve and a fluid reservoir to adjust the position of
the diaphragm to the desired position; and ceasing actuation of the
actuator. In that regard, the diaphragm is maintained in the
desired position after actuation of the actuator has ceased. In
some instances, the diaphragm is maintained in the desired position
after actuation of the actuator has ceased by a pair of opposing
check valves positioned between the cavity of the adjustable valve
and the fluid reservoir. Further, in some instances, the obtained
pressure readings include at least one pressure reading selected
from the group consisting of: a pressure within an anterior chamber
of an eye, a pressure within a drainage location spaced from the
anterior chamber of the eye, and an atmospheric pressure.
[0017] It is to be understood that both the foregoing summary and
the following detailed description are exemplary and explanatory
only and are intended to provide further explanation of the
inventions of the present disclosure. Additional advantages,
purposes, and alternatives to the specific examples provided will
be apparent to one skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate several
embodiments of the present disclosure and together with the
description, serve to explain the principles of the present
disclosure.
[0019] FIG. 1 is a diagram of the front portion of an eye.
[0020] FIG. 2 is a block diagram of an exemplary IOP control system
according to one embodiment of the present disclosure.
[0021] FIG. 3 is a diagram of an IOP sensor system according to one
embodiment of the present disclosure.
[0022] FIG. 4 is a diagram of a drainage device incorporating an
IOP sensor system according to one embodiment of the present
disclosure.
[0023] FIG. 5 is a diagrammatic schematic view of a valve system
according to one embodiment of the present disclosure.
[0024] FIG. 6 is a diagrammatic schematic view of a valve system
according to another embodiment of the present disclosure.
[0025] FIG. 7 is a diagrammatic schematic view of a valve system
according to another embodiment of the present disclosure.
[0026] FIG. 8 is a diagrammatic cross-sectional schematic view of a
valve system according to an embodiment of the present disclosure
showing a diaphragm of the valve system in a first orientation.
[0027] FIG. 9 is a diagrammatic cross-sectional schematic view of
the valve system of FIG. 8 showing the diaphragm of the valve
system in a second orientation.
[0028] FIG. 10 is a diagrammatic schematic view of a valve system
according to another embodiment of the present disclosure.
[0029] FIG. 11 is a diagrammatic schematic view of a valve system
according to another embodiment of the present disclosure.
[0030] FIG. 12 is a diagrammatic schematic view of a valve system
according to another embodiment of the present disclosure.
[0031] FIGS. 13-17 are sequential diagrammatic schematic views of
the valve system of FIG. 12 illustrating operation of the valve
system. In particular, FIG. 13 is a diagrammatic schematic view of
the valve system of FIG. 12 showing a diaphragm of the valve system
in a first orientation.
[0032] FIG. 14 is a diagrammatic schematic view of the valve system
of FIG. 12 showing transition of the diaphragm from the first
orientation illustrated in FIG. 13 to a second orientation.
[0033] FIG. 15 is a diagrammatic schematic view of the valve system
of FIG. 12 showing the diaphragm in the second orientation of FIG.
14.
[0034] FIG. 16 is a diagrammatic schematic view of the valve system
of FIG. 12 showing transition of the diaphragm from the second
orientation illustrated in FIG. 15 to a third orientation.
[0035] FIG. 17 is a diagrammatic schematic view of the valve system
of FIG. 12 showing the diaphragm in the third orientation of FIG.
16.
[0036] FIG. 18 is a diagrammatic top view of a boss valve system
according to an embodiment of the present disclosure.
[0037] FIG. 19 is a diagrammatic cross-sectional side view of the
boss valve system of FIG. 18 showing a diaphragm of the boss valve
system in a first orientation.
[0038] FIG. 20 is a diagrammatic cross-sectional side view of the
boss valve system of FIG. 18 similar to that of FIG. 19, but
showing the diaphragm of the boss valve system in a second
orientation.
[0039] FIG. 21a is a diagrammatic top view of a valve system
according to another embodiment of the present disclosure
illustrating fluid flow into a cavity adjacent a diaphragm.
[0040] FIG. 21b is a diagrammatic cross-sectional side view of the
valve system of FIG. 21a, showing the diaphragm of the valve system
in a first orientation associated with fluid flow into the
cavity.
[0041] FIG. 22a is a diagrammatic top view of the valve system
FIGS. 21a and 21b illustrating fluid flow out of the cavity and
into a fluid reservoir.
[0042] FIG. 22b is a diagrammatic cross-sectional side view of the
valve system of FIG. 22a, showing the diaphragm of the valve system
in a second orientation associated with fluid flow out of the
cavity and into the fluid reservoir.
[0043] FIG. 23 is a diagrammatic cross-sectional side view of
layers of a valve system according to an embodiment of the present
disclosure.
[0044] FIG. 24 is a diagrammatic cross-sectional side view of the
valve system formed of the layers shown in FIG. 23.
[0045] FIG. 25 is a diagrammatic top view of the valve system of
FIG. 24 according to one embodiment of the present disclosure.
[0046] FIG. 26 is a diagrammatic schematic view of a valve system
of the present disclosure interfacing with a lumen, where a
diaphragm of the valve system is shown in a first orientation with
respect to the lumen.
[0047] FIG. 27 is a diagrammatic schematic view of a valve system
of the present disclosure interfacing with a lumen similar to FIG.
26, but showing the diaphragm of the valve system in a second
orientation with respect to the lumen.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0048] For the purposes of promoting an understanding of the
principles of the present disclosure, reference will now be made to
the embodiments illustrated in the drawings, and specific language
will be used to describe the same. It will nevertheless be
understood that no limitation of the scope of the disclosure is
intended. Any alterations and further modifications to the
described devices, instruments, methods, and any further
application of the principles of the present disclosure are fully
contemplated as would normally occur to one skilled in the art to
which the disclosure relates. In particular, it is fully
contemplated that the features, components, and/or steps described
with respect to one embodiment may be combined with the features,
components, and/or steps described with respect to other
embodiments of the present disclosure. For simplicity, in some
instances the same reference numbers are used throughout the
drawings to refer to the same or like parts.
[0049] In some particular instances, embodiments of the present
disclosure are configured to be part of the glaucoma drainage
devices disclosed in U.S. patent application Ser. No. 12/832,449
filed Jul. 8, 2010, U.S. application Ser. No. 12/685,772 filed Jan.
12, 2010, U.S. application Ser. No. 12/609,043 filed Oct. 30, 2009,
and U.S. application Ser. No. 12/563,244 filed Sep. 21, 2009, each
of which is hereby incorporated by reference in its entirety for
this purpose.
[0050] FIG. 2 is a block diagram of an exemplary IOP control system
200 implantable in an eye of a patient for the treatment of
glaucoma or other conditions. The IOP control system 200 is
configured in a manner that provides IOP pressure control, but also
regulates and controls bleb pressures, reducing complications
arising from surgical implant glaucoma treatments. In FIG. 2, the
IOP control system 200 includes a power source 205, an IOP sensor
system 210, a processor 215, a memory 220, a valve system 230, and
a data transmission module 225.
[0051] The power source 205 is typically a rechargeable battery,
such as a lithium ion or lithium polymer battery, although other
types of batteries may be employed. In addition, any other type of
power cell is appropriate for power source 205. Power source 205
provides power to the system 200, and more particularly to
processor 215. Power source 205 can be recharged via an RFID link
or other type of magnetic coupling.
[0052] Processor 215 is typically an integrated circuit with power,
input, and output pins capable of performing logic functions. In
various embodiments, processor 215 is a targeted device controller.
In such a case, processor 215 performs specific control functions
targeted to a specific device or component, such as a data
transmission module 225, power source 205, sensing system 210,
valve system 230, or memory 220. In other embodiments, processor
215 is a microprocessor. In such a case, processor 215 is
programmable so that it can function to control more than one
component of the device. In other cases, processor 215 is not a
programmable microprocessor, but instead is a special purpose
controller configured to control different components that perform
different functions.
[0053] Memory 220 is typically a semiconductor memory such as RAM,
FRAM, or flash memory. Memory 220 interfaces with processor 215. As
such, processor 215 can write to and read from memory 220. For
example, processor 215 can be configured to read data from the IOP
sensor system 210 and write that data to memory 220. In this
manner, a series of IOP readings can be stored in memory 220.
Processor 215 is also capable of performing other basic memory
functions, such as erasing or overwriting memory 220, detecting
when memory 220 is full, and other common functions associated with
managing semiconductor memory.
[0054] Data transmission module 225 may employ any of a number of
different types of data transmission. For example, data
transmission module 225 may be an active device such as a radio.
Data transmission module 225 may also be a passive device such as
the antenna on an RFID tag. In this case, an RFID tag includes
memory 220 and data transmission module 225 in the form of an
antenna. An RFID reader can then be placed near the system 200 to
write data to or read data from memory 220. Since the amount of
data typically stored in memory 220 is likely to be small
(consisting of IOP readings over a period of time), the speed with
which data is transferred is not crucial. Other types of data that
can be stored in memory 220 and transmitted by data transmission
module 225 include, but are not limited to, power source data (e.g.
low battery, battery defect), speaker data (warning tones, voices),
IOP sensor data (IOP readings, problem conditions), time stamp data
and the like.
[0055] Alternatively, data transmission module 225 may be activated
to communicate an elevated IOP condition to a secondary device such
as a PDA, cell phone, computer, wrist watch, custom device
exclusively for this purpose, remote accessible data storage site
(e.g. an internet server, email server, text message server), or
other electronic device. In one embodiment, a personal electronic
device uploads the data to the remote accessible data storage site
(e.g. an internet server, email server, text message server).
Information may be uploaded to a remote accessible data storage
site so that it can be viewed in real time, for example, by medical
personnel. For example, in a hospital setting, after a patient has
undergone glaucoma surgery and had system 200 implanted, a
secondary device may be located next to the patient's hospital bed.
Since TOP fluctuations are common after glaucoma surgery (both on
the high side and on the low side which is also a dangerous
condition), processor 215 can read TOP measurements made by an
implanted IOP sensor 210. If processor 215 reads an unsafe IOP
condition, data transmission module 225 can alert the patient and
medical staff directly or by transmitting the unsafe readings to a
secondary device.
[0056] FIG. 3 is a diagram of the exemplary IOP sensor system 210,
the drainage tube 430, valve system 230, and divider 350. In FIG.
3, the exemplary IOP sensor system 210 includes three pressure
sensors, P1, P2, and P3. Pressure sensor P1 is located in or is in
fluidic communication with the anterior chamber 340, the pressure
sensor P2 is located at a drainage site in the subconjunctival
space and is arranged to measure bleb pressure, and pressure sensor
P3 is located remotely from P1 and P2 in manner to measure
atmospheric pressure. In some embodiments, pressure sensor P1 is
located in a lumen or tube that is in fluid communication with the
anterior chamber.
[0057] The drainage tube 430 drains aqueous from the anterior
chamber 340 of the eye. The valve system 230 controls the flow of
aqueous through the drainage tube 430. In the embodiment shown, the
pressure sensor P1 measures the pressure in the tube 430 upstream
from the valve system 230 and downstream from the anterior chamber
340. In this manner, pressure sensor P1 measures the pressure in
the anterior chamber 340. The expected measurement discrepancy
between the true anterior chamber pressure and that measured by P1
when located in a tube downstream of the anterior chamber (even
when located between the sclera and the conjunctiva) is very
minimal. For example, Poiseuille's law for pipe flow predicts a
pressure drop of 0.01 mmHg across a 5-millimeter long tube with a
0.300 millimeter inner diameter for a flow rate of 3 microliters
per minute of water.
[0058] In some embodiments, the divider 350 separates pressure
sensor P2 from pressure sensor P3. Pressure sensor P2 is located at
a drainage site (e.g. 410 in FIG. 4). As such, pressure sensor P2
may be located in a pocket, such as a bleb, that generally contains
aqueous or in communication with such a pocket, via a tube for
example and is in a wet location 410. Pressure sensor P3 is
physically separated from pressure sensor P2 by divider 350.
Divider 350 is a physical structure that separates the wet location
410 of P2 from the relatively dry (mechanically unstressed)
location 360 of P3. In some embodiments, divider 350 is included
when the system of the present invention is located on a single
substrate. In this configuration, all three pressure sensors (P1,
P2, and P3) are located on a substrate that includes tube 430,
valve system 230, divider 350, and the other components of the
system. Note that the divider 350 may take many forms, such as but
not limited to a tube fluidically coupling pressure sensor P3 to a
s site away from the substrate or as a pocket residing on the top
portion of the substrate away from and fluidically independent of
the drainage site.
[0059] In some embodiments of the present invention, the
atmospheric pressure sensor P3 is located in close proximity to the
eye, and in one embodiment, the pressure sensor P3 may be implanted
in the eye under the conjunctiva. In such a case, pressure sensor
P3 measures a pressure that can be correlated with atmospheric
pressure. For example, true atmospheric pressure can be a function
of the pressure reading of pressure sensor P3. Pressure sensor P3
may also be located in a dry portion 360 of the subconjunctival
space, separate from the drainage location. Regardless of location,
pressure sensor P3 is intended to measure atmospheric pressure in
the vicinity of the eye or at the eye's surface. One embodiment of
the location of P3 is that if the system has the standard Glaucoma
Drainage Device (GDD) plate-style shape, then P3 may reside on the
top with a barrier preventing it from being crushed while still
allowing pressure communication through the conjunctiva and P2
resides on the bottom in direct contact with the drainage site. In
a distinctly different embodiment, P3 is not located on the implant
but is located outside of the eye as part of a separate external
component or subsystem such as a wearable (e.g. glasses, hat,
headband) or a device that resides in proximity (e.g. a pillow,
nightstand). Such as subsystem, which may or may not include sensor
P3, may include the external recharging implant that is at least
temporarily placed near the implant location in order to recharge
the implant power source 205 and or download data from memory 220
via the data transmission module 225.
[0060] Generally, IOP is a gauge pressure reading--the difference
between the absolute pressure in the eye (as measured by P1) and
atmospheric pressure (as measured by P3). Atmospheric pressure,
typically about 760 mm Hg, often varies in magnitude by 10 mmHg or
more depending on weather conditions or indoor climate control
systems. In addition, the effective atmospheric pressure can vary
significantly--in excess of 100 mmHg--if a patient goes swimming,
hiking, riding in an airplane, etc. Such a variation in atmospheric
pressure is significant since IOP is typically in the range of
about 15 mm Hg. Thus, for accurate monitoring of IOP, it is
desirable to have pressure readings for the anterior chamber (as
measured by P1) and atmospheric pressure in the vicinity of the eye
(as measured by sensor P3).
[0061] Therefore, in one embodiment of the present invention,
pressure readings are taken by P1 and P3 simultaneously or nearly
simultaneously over time so that the actual IOP can be calculated
(as P1-P3 or P1-f(P3)), where f(P3) indicates a function of P3. The
pressure readings of P1 and P3 can be stored in memory 220 by
processor 215. They can later be read from memory so that actual
IOP over time can be interpreted by a physician.
[0062] Pressure sensors P1, P2, and P3 can be any type of pressure
sensors suitable for implantation in the eye. They each may be the
same type of pressure sensor, or they may be different types of
pressure sensors. For example, pressure sensors P1 and P2 may be
the same type of pressure sensor (implanted in the eye), and
pressure sensor P3 may be a different type of pressure sensors (in
the vicinity of the eye).
[0063] In another embodiment of the present invention, pressure
readings taken by pressure sensors P1 and P2 can be used to control
a device that drains aqueous from the anterior chamber 340. FIG. 4
is a diagram of one possible application of the sensors in a system
utilizing the readings of pressures sensors P1-P3. In FIG. 4,
pressure sensor P1 measures the pressure in the anterior chamber
340 of the eye. Pressure sensor P2 measures the pressure at a
drainage site 410.
[0064] The drainage tube 430 may be arranged to shunt fluid from
the anterior chamber 340 to the drainage location 410, which may be
any of numerous locations within the eye. For example, some tubes
are arranged to shunt aqueous from the anterior chamber 340 to the
subconjunctival space thus forming a bleb under the conjunctiva or
alternatively, to the subscleral space thus forming a bleb under
the sclera. Other tube designs shunt aqueous from the anterior
chamber to the suprachoroidal space, the supraciliary space, the
juxta-uveal space, or to the choroid, forming blebs in those
respective locations. In other applications, the drainage tube
shunts aqueous from the anterior chamber to Schlemm's canal, a
collector channel in Schlemm's canal, or any of a number of
different blood vessels like an episcleral vein. In some examples,
the drainage tube even shunts aqueous from the anterior chamber to
outside the conjunctiva. Each of these different anatomical
locations to which aqueous is shunted is an example of a drainage
location 410. Other examples of a drainage location 410 include,
but are not limited to: a subconjunctival space, a suprachoroidal
space, a subscleral space, a supraciliary space, Schlemm's canal, a
collector channel, an episcleral vein, and a uveo-scleral
pathway.
[0065] In FIG. 4, the tube 430 with the valve system 230 on one end
is located with one end in the anterior chamber 340 and the other
end in the drainage location 410, with P1 located within the
anterior chamber 340. The valve system 230 controls the flow of
aqueous from the anterior chamber 340 to drainage location 410. As
indicated above, the pressure sensor P1 is located in the anterior
chamber (as illustrated in FIG. 4) or located in the
subconjunctival space in fluid communication with the anterior
chamber 340 (as illustrated in FIG. 3), in either version pressure
sensor P1 is located upstream from valve system 230.
[0066] Since pressure sensor P1 measures the pressure in the
anterior chamber 340 and pressure sensor P2 measures pressure at
the drainage location 410, the difference between the readings
taken by these two pressure sensors (P1-P2) provides an indication
of the pressure differential between the anterior chamber 340 and
the drainage location 410. In one embodiment, this pressure
differential dictates the rate of aqueous flow from the anterior
chamber 340 to the drainage location 410.
[0067] One complication involved with surgery that shunts the
anterior chamber 340 to a drainage location 410 is hypotony--a
dangerous drop in IOP that can result in severe consequences. It is
desirable to control the rate of aqueous outflow from the anterior
chamber 340 to the drainage location 410 so as to prevent hypotony.
Readings from pressure sensors P1, P2, and P3 can be used to
control the flow rate through tube 430 by controlling the valve
system 230. For example, the valve system 230 can be controlled
based on the pressure readings from pressure sensors P1, P2, and
P3.
[0068] In another embodiment of the present invention, IOP (based
on readings from pressure sensor P1 and pressure sensor P3) can be
controlled by controlling valve system 230. In this manner, IOP is
the control parameter. To accomplish this, the valve system 230 can
be adjusted to maintain a particular IOP (like an IOP of 15 mm Hg).
Valve system 230 may be opened more at night than during the day to
maintain a particular IOP. In other embodiments, an IOP drop can be
controlled. Immediately after surgery, IOP can drop precipitously.
Valve system 230 can be adjusted to permit a gradual drop in IOP
based on readings from pressure sensors P1 and P3. Note that the
physician would be able to set the high/low IOP thresholds
wirelessly to meet each patient's specific requirements.
[0069] In another embodiment of the present invention, readings
from pressure sensor P2 (or from the difference between pressure
sensor P2 and atmospheric pressure as measured by P3) can be used
to control valve system 230 so as to control the morphology of a
bleb. One of the problems associated with implant surgery is bleb
failure. A bleb can fail due to poor formation or fibrosis. The
pressure in the bleb is one factor that determines bleb morphology.
As explained above, too much pressure can cause a bleb to migrate
to an undesirable location or can lead to fibrosis. The pressure of
the bleb can be controlled by using the reading from pressure
sensor P2 (at drainage location 410--in this case, a bleb). In one
embodiment of the present invention, the difference between the
pressure in the bleb (as measured by P2) and atmospheric pressure
(as measured by P3) can be used to control valve system 230 to
maintain a desired bleb pressure. In this manner, the pressure
sensors used to determine IOP as defined in the present invention
can also be used to properly maintain a bleb.
[0070] Valve system 230 may be controlled by microprocessor 215
based on input data received from the sensors. A desired pressure
differential (that corresponds to a desired flow rate) can be
maintained by controlling the operation of valve system 230.
Likewise, a desired IOP, IOP change rate, or bleb pressure can be
controlled by controlling the operation of valve system 230.
Furthermore, flow across the valve may drastically vary with
time.
[0071] Finally, there are many other similar uses for the IOP
sensor system 210. For example, various pressure readings can be
used to determine if tube 430 is occluded or obstructed in some
undesirable manner. As such, failure of a drainage device can be
detected. Further, the pressure sensors have configurations other
than those illustrated that are utilized in some embodiments (e.g.,
end cap implementations, incorporation into a portion of a valve
system, etc.). In that regard, the IOP sensor configurations
disclosed in U.S. patent application Ser. No. 12/832,449 filed Jul.
8, 2010, U.S. application Ser. No. 12/685,772 filed Jan. 12, 2010,
U.S. application Ser. No. 12/609,043 filed Oct. 30, 2009, and U.S.
application Ser. No. 12/563,244 filed Sep. 21, 2009, each of which
is hereby incorporated by reference in its entirety for this
purpose, are utilized in some instances. In that regard, readings
from the IOP sensor configurations are utilized to control the
valve systems of the present disclosure in some embodiments.
[0072] Referring now to FIG. 5, shown therein is a diagrammatic
schematic view of a valve system 500 according to one embodiment of
the present disclosure. As shown, the valve system 500 includes an
adjustable valve 502. The adjustable valve 502 is comprised of a
housing 504 that defines a cavity 506 that contains a fluid. A
membrane or diaphragm 508 is coupled to the housing 504 such that
the diaphragm defines an upper boundary of the cavity 506. In that
regard, the diaphragm 508 is formed of a material that is more
flexible than the material forming the housing 504 such that the
diaphragm 508 is movable between different positions based upon the
amount of fluid and/or pressure within the cavity 506. In some
instances, the diaphragm 508 is formed of silicone rubber,
polyimide, a thin silicon membrane, Parylene, a thin silicon
nitride membrane, gold, Parylene/gold/Parylene composite membranes
and the like and/or other suitable materials. As the amount of
fluid within the cavity 506 is increased, the pressure within the
cavity increases, which results in the displacement of the
diaphragm 508 away from the cavity (upwards as viewed in FIG. 5).
An exemplary displaced position of the diaphragm 508 corresponding
to an increased amount of fluid and pressure within cavity 506 is
illustrated in phantom in FIG. 5. In some instances, the adjustable
valve 502 is implemented as a boss valve (e.g., similar to the boss
valve illustrated in FIGS. 18-20 and described below).
[0073] In order to control the amount of fluid within the cavity
506 and, thereby, the relative position of the diaphragm 508, the
adjustable valve 502 is in communication with a fluid reservoir
510. The fluid reservoir 510 includes a housing 512 that defines a
cavity 514 that also contains fluid. In the present embodiment, the
housing 512 is formed of a relatively rigid material, such as
glass, polymer (e.g. polycarbonate), silicon, silicon dioxide,
metal such as titanium, etc. In that regard, the housing 512 is
designed to maintain its shape in the current embodiment.
Accordingly, the housing 512 defines a constant volume for cavity
514 during use.
[0074] The cavity 506 of the adjustable valve 502 is in fluid
communication with the cavity 514 of the fluid reservoir 510. This
allows a flow of fluid between the cavities 506 and 514 such that a
desired amount of fluid is held within cavity 506 in order to
maintain the diaphragm 508 in a desired position. In that regard, a
lumen 516 extends from cavity 506 to a check valve 518. Check valve
518 allows fluid flow only in the direction away from cavity 506
and towards cavity 514. That is, check valve 518 prevents fluid
flow from cavity 514 towards cavity 506. A lumen 520 connects lumen
516 and check valve 518 to a lumen 522 that extends from cavity
514. In that regard, in the illustrated embodiment lumen 522 serves
as both an egress and ingress lumen for cavity 514, as discussed
below. In other embodiments, two separate lumens are provided, one
for egress of fluid from cavity 514 and one for ingress of fluid to
cavity 514.
[0075] In the illustrated embodiment, in addition to being in fluid
communication with lumen 520, lumen 522 is also in fluid
communication with lumen 524. Lumen 524, in turn, extends to a
check valve 526. Check valve 526 allows fluid flow only in the
direction away from cavity 514 and towards cavity 506. That is,
check valve 526 prevents fluid flow from cavity 506 towards cavity
514. A lumen 528 connects lumen 524 and check valve 526 to cavity
506. Generally, the check valves 518, 526 can have any desired
cracking pressure. In some instances, check valve 526 has a
cracking pressure near zero (for example, 0.1 mmHg or lower) and
check valve 518 has a cracking pressure approximately equal to the
pressure required to maintain membrane 508 in the maximum outward
position meaning valve 502 is fully closed. For example, such a
pressure might be 100 mmHg with a tolerance of about 5 mmHg. In
such an embodiment, the cavity 514 operates as an electrolysis
bubble chamber (see below). Actuation of electrodes 532 and 534
cause bubbles to form in the fluid within cavity 514 thereby
causing pressure to increase and liquid to flow through lumens 522
and 524, check valve 526, lumen 528 and into cavity 506. This
causes pressure in cavity 506 to increase thereby expanding
membrane 508 of valve 502. Once membrane 508 is set to a desired
location, the pressure in cavity 506 is approximately equal to the
pressure of cavity 514. The pressure in cavity 514 then decays
either naturally or by intent (i.e. via reversing electrical
operation of voltage source 530); however, pressure in cavity 506
is temporarily maintained by check valve 518--until pressure
difference is greater than that of the cracking pressure of check
valve 518. Once pressure difference across check valve 518 is
greater than its cracking pressure, flow is initiated from cavity
506 to cavity 514 and membrane 508 is lowered; that is, valve 502
becomes more open. In such an embodiment, the lowest setting of
membrane 508 occurs at some intermediate pressure between zero and
the maximum design pressure (e.g. 100 mmHg), for example,
approximately half (50 mmHg). The non-zero pressure is realized
since the non-zero check valve requires that some of the working
fluid remain in cavity 506. The design then of valve 502 is such
that the membrane 508's location--relative to the channel in which
it lies--produces the maximum open design pathway when the minimum
(though non-zero) pressure is achieved in cavity 506. As the
function of the check valves is to ensure that fluid flows in a
particular direction or pressure gradient, any type of check valve
or one way valve may be used, including, for example, a flapper or
Reed valve.
[0076] The valve system 500 also includes a voltage source 530 that
is in electrical communication with the fluid within cavity 514.
More specifically, a pair of electrodes 532 and 534 that are
connected to the voltage source 530 are positioned in electrical
communication with the fluid within cavity 514. The electrodes 532,
534 are formed of a conductive material, such as platinum, gold,
copper, silver, silver-chloride, and/or other conductive materials.
Voltage for gas generation via electrolysis of water is typically
about 1.2 V for Platinum electrodes. Electrical currents are in the
order of fractions of micro amps to several micro amps. The faster
the actuation desired, the higher the current level that can be
chosen. The higher the cell's overall electrical resistance,
including through the electrolyte, the higher the power that will
be required for a given performance level (measured by parameters
such as pressure vs time for instance).
[0077] In use, a voltage is applied across electrodes 532, 534 in
order to cause the formation of bubbles within cavity 514. In some
instances, the bubbles are formed through electrolysis. In that
regard, the fluid utilized within the valve system 500 is an
electrolysis solution, which is typically water with a small
electrolytic additive such as a salt and/or one or more of the
following: KNO3, H2SO4, CaSO4, MgSO4, CaCO3, K2SO4, Na2SO4, LiSO4,
NaOH, KOH, H2NO4, and CuSO4. If salt additive is used, the solution
could be Balanced Salt Solution (BSS) which is commonly introduced
into the eye during ophthalmic surgery (though possibly unwanted
gases may be generated during the process). The electrodes 532, 534
apply voltage to the volume of water or saline solution within the
cavity 514 to cause the electrolysis. As is known, electrical
current applied through water (via a voltage applied across one or
more pair of electrodes) results in the breaking of the molecular
bonds of the water to produce hydrogen and oxygen gases. Since the
volume of the resulting gases is much greater than the
corresponding volume of the water that produces the gases and the
housing 512 defines a constant volume for cavity 514, the pressure
within cavity 514 is increased by the creation of the gases. With
the increased pressure, fluid will be forced out of cavity 514
towards cavity 506. As the amount of fluid within cavity 506 is
increased, the diaphragm 508 will be displaced upward, as viewed in
FIG. 5.
[0078] As the gases within cavity 514 recombine (i.e., return to a
liquid state with a reduced volume) the pressure within cavity 514
will decrease. When the pressure within cavity 514 becomes less
than the pressure within cavity 506, fluid will flow from cavity
506 towards cavity 514. As the amount of fluid within cavity 506 is
decreased, the diaphragm 508 will be displaced downward, as viewed
in FIG. 5. In some instances, reversing the voltage applied by the
electrodes 532, 534 speeds up the recombination process.
Accordingly, in some instances the pressure within cavity 514 can
be controlled by regulating the voltage applied to the electrodes
532, 534 in order to vary the positioning of diaphragm 508. In that
regard, by controlling the pressure within cavity 514, the flow of
fluid between cavity 514 and cavity 506 is likewise controlled. In
that regard, in some instances a processor in communication with an
TOP sensor configuration is utilized to determine an appropriate
position for the diaphragm 508 and the corresponding voltage, if
any, that should be applied by the voltage source 530 to cause the
appropriate flow of fluid between the cavities 506, 514 to achieve
the desired diaphragm position. It is understood that processor and
IOP sensor based control may be utilized to control the positions
of valve(s)/diaphragm(s) with each of the systems of the present
disclosure, even if such control is not explicitly mentioned with
respect to a particular system.
[0079] The arrangement of valve system 500 has significant
advantages over a direct bubble-actuation system (e.g., where
electrolysis or thermal bubble generation is performed directly
within the cavity 506). For example, the check valves 518, 526 help
to maintain a constant pressure within the cavity 506 and a
corresponding fixed position of diaphragm 508 for longer periods of
time. In that regard, in a direct bubble-actuation arrangement the
pressure is constantly changing (e.g., decreasing during
recombination), which results in a corresponding constant change in
the diaphragm position. It is understood that while the operation
of valve system 500 has been described in terms of electrolysis,
other types of chemical reactions, thermal nucleation, and/or
mechanical arrangements (like a piston or other moving part) may be
used to change the pressure and/or volume of cavity 514 to achieve
similar functionality.
[0080] In an alternative embodiment, one of the electrodes 532 or
534 is positioned in electrical communication with cavity 514,
while the other electrode 532 or 534 is positioned in electrical
communication with cavity 506 (See, for example, FIG. 12 for a
similar arrangement of electrodes). By separating the two
electrodes between the two cavities 506 and 514, recombination of
the bubbles to once again form liquid water is slowed because of
the spatially separated generation of H.sub.2 and O.sub.2.
[0081] In some instances, the valve system 500 is selectively moved
between positions that obstruct fluid flow through an adjacent
lumen (see, for example, FIGS. 26 and 27). The ability of the
diaphragm 508 to be displaced allows for a variable level of flow
restriction through the lumen by the varying how far into the lumen
the diaphragm goes. In some instances, the diaphragm 508 is movable
between a position that does not block the lumen at all (0%
blockage), a position that blocks the lumen completely (100%
blockage), and positions therebetween that partially block the
lumen (0.01-99.9% blockage). The particular range of lumen
blockages provided by the valve system 500 can be selected for
particular uses and may include any subset of lumen blockages
between 0% and 100% blockage. In one use, the valve system 500
controls the amount of aqueous that enters the drainage location
and exits the anterior chamber of the eye. In some instances, the
valve system 500 controls the aqueous flow based on readings from
pressure sensor(s), such as P1, P2, and P3, as described above.
[0082] Controlling aqueous flow can reduce the chances of hypotony
after filtration surgery, maintain a suitable IOP, and/or control
the amount of stagnant aqueous in the drainage location. When the
drainage location is a subconjunctival bleb, controlling the amount
of stagnant aqueous in the bleb can help maintain proper bleb
morphology and reduce the amount of fibrosis. Too much stagnant
aqueous in a bleb can lead to fibrosis. It has been postulated that
fibroblasts form in stagnant aqueous and that too much tension on
the bleb wall (i.e., too high a pressure in the bleb) can lead to
bleb failure. Accordingly, the use of valves and valve systems of
the present disclosure, including valve system 500, can lead to
proper bleb maintenance, which decreases the chances of these
deleterious side effects. In some instances, the diaphragm 508 is
repeatedly transitioned between an open position and a closed
position to cause a flow of fluid through an associated lumen
(i.e., the diaphragm is utilized to pump fluid). In this manner,
the valves and valve systems of the present disclosure can be
utilized as a pump system.
[0083] Referring now to FIG. 6, shown therein is a diagrammatic
schematic view of a valve system 540 according to another
embodiment of the present disclosure. As shown, the valve system
540 includes an adjustable valve 502 similar to that of valve
system 500. The adjustable valve 502 is comprised of a housing 504
that defines a cavity 506 that contains fluid. A membrane or
diaphragm 508 is coupled to the housing 504 such that the diaphragm
defines an upper boundary of the cavity 506. In that regard, the
diaphragm 508 is formed of a material that is more flexible than
the material forming the housing 504 such that the diaphragm 508 is
movable between different positions based upon the amount of fluid
and/or pressure within the cavity 506. As the amount of fluid
within the cavity 506 is increased, the pressure within the cavity
increases, which results in the displacement of the diaphragm 508
away from the cavity (upwards as viewed in FIG. 6). An exemplary
displaced position of the diaphragm 508 corresponding to an
increased amount of fluid and pressure within cavity 506 is
illustrated in phantom.
[0084] In order to control the amount of fluid within the cavity
506 and, thereby, the relative position of the diaphragm 508, the
adjustable valve 502 is in communication with a fluid reservoir
542. The fluid reservoir 542 includes a housing that defines a
cavity 544 that also contains fluid. In the present embodiment, the
housing of the fluid reservoir 542 is formed of a relatively
flexible material, such as Parylene, silicone rubber, thin silicon
membranes, Parylene/Au/Parylene composites, polyimide, thin silicon
nitride membranes, gold membranes and the like. In some instances,
the housing is an expandable pouch or bag. In that regard, the
housing of fluid reservoir 542 is designed to inflate and deflate
depending on the amount of fluid received within cavity 544.
Accordingly, the housing defines a varying volume for cavity 544
during use.
[0085] The cavity 506 of the adjustable valve 502 is in fluid
communication with the cavity 544 of the fluid reservoir 542. This
allows a flow of fluid between the cavities 506 and 544 such that a
desired amount of fluid is held within cavity 506 in order to
maintain the diaphragm 508 in a desired position. In that regard, a
fluid channel 546 extends from cavity 506 to a check valve 548.
Check valve 548 allows fluid flow only in the direction away from
cavity 506 and towards cavity 544. That is, check valve 548
prevents fluid flow from cavity 544 towards cavity 506. A fluid
channel 550 connects fluid channel 546 and check valve 548 to
another check valve 552.
[0086] Similar to check valve 548, check valve 552 allows fluid
flow only in the direction away from cavity 506 and towards cavity
544. A fluid channel 554 connects check valve 552 to a fluid
channel 556 that extends from cavity 544. In that regard, in the
illustrated embodiment, fluid channel 556 serves as both an egress
and ingress fluid channel for cavity 544. In other embodiments, two
separate fluid channels are provided, one for egress of fluid from
cavity 544 and one for ingress of fluid to cavity 544.
[0087] In the illustrated embodiment, in addition to being in fluid
communication with fluid channel 554, fluid channel 556 is also in
fluid communication with fluid channel 558. Fluid channel 558, in
turn, extends to a check valve 560. Check valve 560 allows fluid
flow only in the direction away from cavity 544 and towards cavity
506. That is, check valve 560 prevents fluid flow from cavity 506
towards cavity 544. A fluid channel 562 connects fluid channel 558
and check valve 560 to another check valve 564. Similar to check
valve 560, check valve 564 allows fluid flow only in the direction
away from cavity 544 and towards cavity 506. A fluid channel 565
connects check valve 564 to cavity 506. Generally, the check valves
548, 552, 560, and 564 can have any desired cracking pressure. As
the function of the check valves is to ensure that fluid flows in a
particular, any type of check valve or one way valve may be used,
including, for example, a flapper or Reed valve.
[0088] The valve system 540 also includes a bubble chamber 566 that
is in communication with fluid channel 550. More specifically, a
flexible membrane or diaphragm 568 of the bubble chamber is in
communication with the fluid channel 550. In that regard, the
diaphragm 568 can be selectively moved between positions that
occupy varying amounts of the volume of the fluid channel. In some
instances, the diaphragm 568 is movable between a position that
does not occupy the fluid channel at all (0% occupation), a
position that occupies the entire fluid channel completely (100%
occupation), and positions therebetween that partially occupy the
fluid channel (0.01-99.9% occupation). The particular range of
fluid channel occupations provided by the diaphragm can be selected
for particular uses and may include any subset of fluid channel
occupations between 0% and 100% occupation. Two exemplary positions
of the diaphragm 568 are shown in FIG. 6 (an increased occupation
position is shown in phantom).
[0089] A voltage source 570 is in electrical communication with a
fluid within the bubble chamber 566. More specifically, electrodes
coupled to the voltage source 570 are positioned in electrical
communication with the fluid within bubble chamber. In use, a
voltage is applied across the electrodes in order to cause the
formation of bubbles within the bubble chamber 566. In some
instances, the bubbles are formed through electrolysis. In that
regard, the fluid received within the bubble chamber 572 is an
electrolysis solution, which is typically water with a small
electrolytic additive such as a salt and/or one or more of the
following: KNO3, H2SO4, CaSO4, MgSO4, CaCO3, K2SO4, Na2SO4, LiSO4,
NaOH, KOH, H2NO4, and CuSO4. If salt additive is used, the solution
could be Balanced Salt Solution (BSS) which is commonly introduced
into the eye during ophthalmic surgery (though note the potential
unwanted gases associated with electrolysis of BSS, as mentioned
previously). The electrodes apply a voltage to the volume of fluid
within the bubble chamber 566 to cause electrolysis. As is known,
electrical current applied through water (via a voltage applied
across one or more pair of electrodes) results in the breaking of
the molecular bonds of the water to produce hydrogen and oxygen
gases. Since the volume of the resulting gases is greater than the
corresponding volume of the water that produces the gases, the
diaphragm 568 will be displaced upward, as viewed in FIG. 6. As the
diaphragm 568 is displaced upward it will occupy a greater amount
of the volume of the fluid channel 550, which will force the fluid
within fluid channel 550 towards cavity 544. In that regard, check
valves 548 and 552 ensure that fluid flows only the direction away
from cavity 506 and towards cavity 544 as the diaphragm 568
increases the amount of occupation of fluid channel 550.
[0090] As the gases within bubble chamber 566 recombine (i.e.,
return to a liquid state with a reduced volume) the diaphragm will
be displaced downward, as viewed in FIG. 6. In some instances,
reversing the voltage applied by the electrodes of the voltage
source 570 speeds up the recombination process. As the diaphragm is
displaced downward it will occupy a lesser amount of the volume of
the fluid channel 550, which will create a negative gauge pressure
within fluid channel 550 causing fluid to flow from cavity 506
through check valve 548 and into fluid channel 550 towards cavity
544. Accordingly, in some instances the displacement of the
diaphragm 568 of the bubble chamber 566 is controlled by regulating
the voltage applied to the electrodes of the voltage supply 570. In
that regard, by controlling the electrolysis process within the
bubble chamber 566, the flow of fluid from cavity 506 to cavity 544
is likewise controlled. While the operation of bubble chamber 566
has been described in terms of electrolysis, other types of
chemical reactions, thermal nucleation, and/or mechanical
arrangements (like a piston or other moving part) may be used to
change the position of diaphragm 568.
[0091] In one embodiment, check valves 548 and 552 and bubble
chamber 566 together function as a one way pumping system, forcing
fluid on command to flow from cavity 506 to cavity 544. In order to
maintain pressure in cavity 506 when desired, check valve 548 has a
non-zero cracking pressure approximately equal to the pressure
required to maintain membrane 568 in the maximum outward position
meaning valve 502 is fully closed. For example, such a pressure
might be 100 mmHg with a tolerance of about 5 mmHg. In this
instance, check valve 552 has a cracking pressure near zero (for
example, 0.1 mmHg or lower). In this way, if the pressure in 506 is
to be reduced (diaphragm 508 lowered), then activation voltage
supply 570 creates bubbles and thus pressure inside bubble chamber
566 increases, which causes diaphragm 568 to rise. This event
forces fluid from fluid channel 550 through check valve 552. The
relaxation (natural or forced) of bubble chamber 566 and diaphragm
568 will then cause fluid to exit cavity 506 and flow through check
valve 548 into fluid channel 550. Conversely, if it is desired to
raise diaphragm 508, then bubble chamber 568 is not activated but
rather fluid is forced into cavity 506 from cavity 544 via fluid
channel 558. This occurs by the pump-like operation of check valves
564 and 562 and bubble chamber 572 (see below for details regarding
these components). In such a case, check valves 560 and 564 have a
cracking pressure near zero (for example, 0.1 mmHg or lower). Net
flow from cavity 544 to cavity 506 is realized by the repetitive
expansion and contraction of diaphragm 574. That is, when voltage
supply 576 is activated in such that bubbles are generated in
bubble chamber 572, then pressure causes diaphragm 574 to expand
and thus forces fluid from fluid channel 562 to fluid channel 565
(and into cavity 506) through check valve 564. The relaxation
(natural or forced) of bubble chamber 572 and diaphragm 574 will
then cause fluid to exit cavity 544 and flow through check valve
560 into fluid channel 562.
[0092] The valve system 540 also includes a bubble chamber 572 that
is in communication with fluid channel 562. More specifically, a
flexible membrane or diaphragm 574 of the bubble chamber is in
communication with the fluid channel 562. In that regard, the
diaphragm 574 can be selectively moved between positions that
occupy varying amounts of the volume of the fluid channel. In some
instances, the diaphragm 574 is movable between a position that
does not occupy the fluid channel at all (0% occupation), a
position that occupies the entire fluid channel completely (100%
occupation), and positions therebetween that partially occupy the
fluid channel (0.01-99.9% occupation). The particular range of
fluid channel occupations provided by the diaphragm 574 can be
selected for particular uses and may include any subset of fluid
channel occupations between 0% and 100% occupation. Two exemplary
positions of the diaphragm 574 are shown in FIG. 6 (an increased
occupation position is shown in phantom).
[0093] A voltage source 576 is in electrical communication with a
fluid within the bubble chamber 572. More specifically electrodes
coupled to the voltage source 576 are positioned in electrical
communication with the fluid within bubble chamber. In use, a
voltage is applied across the electrodes in order to cause the
formation of bubbles within the bubble chamber 572. In some
instances, the bubbles are formed through electrolysis. In that
regard, the fluid received within the bubble chamber 572 is an
electrolysis solution, which is typically water with a small
electrolytic additive such as a salt and/or one or more of the
following: KNO3, H2SO4, CaSO4, MgSO4, CaCO3, K2SO4, Na2SO4, LiSO4,
NaOH, KOH, H2NO4, and CuSO4. If salt additive is used, the solution
could be Balanced Salt Solution (BSS) which is commonly introduced
into the eye during ophthalmic surgery (though note the potential
unwanted gases associated with electrolysis of BSS, as mentioned
previously). The fluid within bubble chamber 572 may be the same or
different than the fluid received within bubble chamber 566.
[0094] The electrodes of voltage source 576 apply a voltage to the
volume of fluid within the bubble chamber 572 to cause
electrolysis. As is known, electrical current applied through water
(via a voltage applied across one or more pair of electrodes)
results in the breaking of the molecular bonds of the water to
produce hydrogen and oxygen gases. Since the volume of the
resulting gases is greater than the corresponding volume of the
water that produces the gases, the diaphragm 574 will be displaced
upward, as viewed in FIG. 6. As the diaphragm 574 is displaced
upward it will occupy a greater amount of the volume of the fluid
channel 562, which will force the fluid within fluid channel 562
towards cavity 506. In that regard, check valves 560 and 564 ensure
that fluid flows only the direction away from cavity 544 and
towards cavity 506 as the diaphragm 574 increases the amount of
occupation of fluid channel 562.
[0095] As the gases within bubble chamber 572 recombine (i.e.,
return to a liquid state with a reduced volume) the diaphragm will
be displaced downward, as viewed in FIG. 6. In some instances,
reversing the voltage applied by the electrodes of the voltage
source 576 speeds up the recombination process. As the diaphragm is
displaced downward it will occupy a lesser amount of the volume of
the fluid channel 562, which will create a negative gauge pressure
within fluid channel 562 causing fluid to flow from cavity 544
through check valve 560 and into fluid channel 562 towards cavity
506. Accordingly, in some instances the displacement of the
diaphragm 574 of the bubble chamber 572 is controlled by regulating
the voltage applied to the electrodes of the voltage supply 576. In
that regard, by controlling the electrolysis process within the
bubble chamber 572, the flow of fluid from cavity 544 to cavity 506
is likewise controlled. While the operation of bubble chamber 572
has been described in terms of electrolysis, other types of
chemical reactions, thermal nucleation, and/or mechanical
arrangements (like a piston or other moving part) may be used to
change the position of diaphragm 574.
[0096] By coordinating control of the bubble chambers 566 and 572,
the valve system 540 can be utilized to selectively move the
diaphragm 508 of valve 502 between positions that obstruct fluid
flow through an adjacent lumen or fluid channel (See, for example,
FIGS. 26 and 27) in varying amounts. As discussed above with
respect to valve system 500, the ability of the diaphragm 508 to be
displaced allows for a variable level of flow restriction and/or
pumping through the lumen or fluid channel by the varying how far
into the lumen or fluid channel the diaphragm goes.
[0097] Referring now to FIG. 7, shown therein is a diagrammatic
schematic view of a valve system 580 according to another
embodiment of the present disclosure. In that regard, valve system
580 is similar in many respects to valve system 540 described
above, but the valve system 580 does not include check valves 548,
552, 562, and 564. Rather, the valve system 580 relies upon a
nozzle/diffuser arrangement for the fluid channels associated with
the bubble valves 566 and 572 to provide the desired directional
fluid flows. It is understood that, in other embodiments, one or
more check valves (as described above) are utilized in combination
with the nozzle/diffuser arrangement of the present embodiment. In
some specific embodiments, a single one-way check valve is
associated with each of the bubble valves 566, 572 in addition to
the nozzle/diffuser arrangement.
[0098] As shown, the valve system 580 includes an adjustable valve
502 similar to that of valve systems 500 and 540. The adjustable
valve 502 is comprised of a housing 504 that defines a cavity 506
that contains fluid. A membrane or diaphragm 508 is coupled to the
housing 504 such that the diaphragm defines an upper boundary of
the cavity 506. In that regard, the diaphragm 508 is formed of a
material that is more flexible than the material forming the
housing 504 such that the diaphragm 508 is movable between
different positions based upon the amount of fluid and/or pressure
within the cavity 506. As the amount of fluid within the cavity 506
is increased, the pressure within the cavity increases, which
results in the displacement of the diaphragm 508 away from the
cavity (upwards as viewed in FIG. 6). An exemplary displaced
position of the diaphragm 508 corresponding to an increased amount
of fluid and pressure within cavity 506 is illustrated in
phantom.
[0099] In order to control the amount of fluid within the cavity
506 and, thereby, the relative position of the diaphragm 508, the
adjustable valve 502 is in communication with a fluid reservoir
542. The fluid reservoir 542 includes a housing that defines a
cavity 544 that also contains fluid. In the present embodiment, the
housing of the fluid reservoir 542 is formed of a relatively
flexible material such that the housing is configured to inflate
and deflate depending on the amount of fluid received within cavity
544. Accordingly, the housing defines a varying volume for cavity
544 during use.
[0100] The cavity 506 of the adjustable valve 502 is in fluid
communication with the cavity 544 of the fluid reservoir 542. This
allows a flow of fluid between the cavities 506 and 544 such that a
desired amount of fluid is held within cavity 506 in order to
maintain the diaphragm 508 in a desired position. In that regard, a
fluid channel 546 extends from cavity 506 to a fluid channel 554
that extends to a fluid channel 556 that extends from cavity 544.
In that regard, the fluid channels 546, 554, and 556 define a
single continuous channel in some instances. In the illustrated
embodiment, fluid channel 556 serves as both an egress and ingress
fluid channel for cavity 544. In other embodiments, two separate
fluid channels are provided, one for egress of fluid from cavity
544 and one for ingress of fluid to cavity 544. In the illustrated
embodiment, fluid channel 556 is also in fluid communication with
fluid channel 558 that extends to a fluid channel 565 that is in
fluid communication with cavity 506. In that regard, the fluid
channels 556, 558, and 565 define a single continuous channel in
some instances.
[0101] The valve system 580 also includes a bubble chamber 566 that
is in communication with fluid channel 546. More specifically, a
flexible membrane or diaphragm of the bubble chamber is in
communication with the fluid channel 546. In that regard, the
diaphragm can be selectively moved between positions that occupy
varying amounts of the volume of the fluid channel. The particular
range of fluid channel occupations provided by the diaphragm can be
selected for particular uses and may include any subset of fluid
channel occupations between 0% and 100% occupation. Two exemplary
positions of the diaphragm are shown in FIG. 7 (an increased
occupation position is shown in phantom).
[0102] A voltage source 570 is in electrical communication with a
fluid within the bubble chamber 566. More specifically, electrodes
coupled to the voltage source 570 are positioned in electrical
communication with the fluid within the bubble chamber. In use, a
voltage is applied across the electrodes in order to cause the
formation of bubbles within the bubble chamber 566. Since the
volume of the resulting gases is greater than the corresponding
volume of the liquid that produces the gases, the diaphragm of the
bubble chamber will be displaced upward, as viewed in FIG. 7. As
the diaphragm is displaced upward it will occupy a greater amount
of the volume of the fluid channel 546, which will force the fluid
within fluid channel 546 towards cavity 544. In that regard, the
structural arrangement of the fluid channel 546 ensures that fluid
flows only the direction away from cavity 506 and towards cavity
544 as the diaphragm increases the amount of occupation of fluid
channel 546. An example of such a structural arrangement is
described below with respect to FIGS. 8 and 9. In that regard, in
some instances the structural arrangement is a nozzle/diffuser
arrangement that promotes fluid flow in a particular direction.
[0103] As the gases within bubble chamber 566 recombine (i.e.,
return to a liquid state with a reduced volume) the diaphragm will
be displaced downward, as viewed in FIG. 7. In some instances,
reversing the voltage applied by the electrodes of the voltage
source 570 speeds up the recombination process. As the diaphragm is
displaced downward it will occupy a lesser amount of the volume of
the fluid channel 546, which will create a negative gauge pressure
within fluid channel 546 causing fluid to flow from cavity 506 into
fluid channel 546 towards cavity 544. Again, the structural
arrangement of the fluid channel 546 ensures that fluid flows only
the direction away from cavity 506 and towards cavity 544 as the
diaphragm decreases the amount of occupation of fluid channel 546.
While the operation of bubble chamber 566 has been described in
terms of electrolysis, other types of chemical reactions, thermal
nucleation, and/or mechanical arrangements (like a piston or other
moving part) may be used to change the position of diaphragm.
[0104] The valve system 580 also includes a bubble chamber 572 that
is in communication with fluid channel 565. More specifically, a
flexible membrane or diaphragm of the bubble chamber 572 is in
communication with the fluid channel 565. In that regard, the
diaphragm can be selectively moved between positions that occupy
varying amounts of the volume of the fluid channel. The particular
range of fluid channel occupations provided by the diaphragm can be
selected for particular uses and may include any subset of fluid
channel occupations between 0% and 100% occupation. Two exemplary
positions of the diaphragm are shown in FIG. 7 (an increased
occupation position is shown in phantom).
[0105] A voltage source 576 is in electrical communication with a
fluid within the bubble chamber 572. More specifically, electrodes
coupled to the voltage source 576 are positioned in electrical
communication with the fluid within bubble chamber. In use, a
voltage is applied across the electrodes in order to cause the
formation of bubbles within the bubble chamber 572. Since the
volume of the resulting gases is greater than the corresponding
volume of the liquid that produces the gases, the diaphragm of the
bubble chamber will be displaced upward, as viewed in FIG. 7. As
the diaphragm is displaced upward it will occupy a greater amount
of the volume of the fluid channel 565, which will force the fluid
within fluid channel 565 towards cavity 506. In that regard, the
structural arrangement of the fluid channel 565 ensures that fluid
flows only the direction away from cavity 544 and towards cavity
506 as the diaphragm increases the amount of occupation of fluid
channel 565. An example of such a structural arrangement is
described below with respect to FIGS. 8 and 9. In that regard, in
some instances the structural arrangement is a nozzle/diffuser
arrangement that promotes fluid flow in a particular direction.
[0106] As the gases within bubble chamber 572 recombine (i.e.,
return to a liquid state with a reduced volume) the diaphragm will
be displaced downward, as viewed in FIG. 7. In some instances,
reversing the voltage applied by the electrodes of the voltage
source 576 speeds up the recombination process. As the diaphragm is
displaced downward it will occupy a lesser amount of the volume of
the fluid channel 565, which will create a negative gauge pressure
within fluid channel 565 causing fluid to flow from cavity 544 into
fluid channels 556, 558, and 565 towards cavity 506. Again, the
structural arrangement of the fluid channel 565 ensures that fluid
flows only the direction away from cavity 544 and towards cavity
506 as the diaphragm decreases the amount of occupation of fluid
channel. While the operation of bubble chamber 572 has been
described in terms of electrolysis, other types of chemical
reactions, thermal nucleation, and/or mechanical arrangements (like
a piston or other moving part) may be used to change the position
of diaphragm.
[0107] By coordinating control of the bubble chambers 566 and 572,
the valve system 580 can be utilized to selectively move the
diaphragm 508 of valve 502 between positions that obstruct fluid
flow through an adjacent lumen or fluid channel (See, for example,
FIGS. 26 and 27). As discussed above with respect to valve system
500, the ability of the diaphragm 508 to be displaced allows for a
variable level of flow restriction and/or pumping through the lumen
or fluid channel by the varying how far into the lumen or fluid
channel the diaphragm goes.
[0108] Referring now to FIGS. 8 and 9, shown therein are
diagrammatic cross-sectional schematic views of a pump system 590
according to an embodiment of the present disclosure. In
particular, FIG. 8 shows the pump system 590 in a first orientation
and FIG. 9 shows the valve system in a second orientation. More
specifically, FIGS. 8 and 9 illustrate a nozzle/diffuser
arrangement that facilitates directional fluid flow without the use
of a check valve. Accordingly, in some instances, the
nozzle/diffuser arrangement of FIGS. 8 and 9 is utilized with the
bubble chambers 566 and 572 to facilitate the desired directional
fluid flows between cavities 506 and 544.
[0109] As shown in FIG. 8, the pump system 590 includes a housing
592 that defines a cavity 594. The cavity 594 is bounded by a
flexible membrane or diaphragm 596. In that regard, as the pressure
and/or volume of fluid within cavity 594 is increased the diaphragm
596 will be displaced downward, as viewed in FIG. 8. FIG. 9
illustrates an exemplary displaced position of the diaphragm 596.
Referring again to FIG. 8, the diaphragm 596 is in communication
with a fluid channel that includes an opening 598 and an opening
600. In the illustrated embodiment, opening 598 serves as an inlet
and opening 600 serves as an outlet. In that regard, opening 598
has a first end 602 and an opposing second end 604 where the second
end 604 defines an increased cross-sectional area relative to the
first end 602. In the illustrated embodiment, the opening 598 has a
continuous taper from the first end 602 to the second end 604. In
other embodiments, the opening 598 does not have a continuous
taper, but still has ends of differing cross-sectional area. In
this manner, the opening 598 defines a nozzle/diffuser. Similarly,
opening 600 has a first end 606 and an opposing second end 608
where the second end 608 defines an increased cross-sectional area
relative to the first end 606. In the illustrated embodiment, the
opening 600 has a continuous taper from the first end 606 to the
second end 608. In other embodiments, the opening 600 does not have
a continuous taper, but still has ends of differing cross-sectional
area. Further, in the illustrated embodiment, the opening 600 has a
profile that is identical to opening 598, but oriented in the
opposite direction (as viewed in FIG. 8). In other instances, the
opening 600 has a different profile than opening 598. Regardless of
the specific profile, the opening 600 defines a
nozzle/diffuser.
[0110] Together, the openings 598 and 600 facilitate fluid flow
along the path defined by arrows 610, 612, and 614. More
specifically, as the diaphragm 596 is moved between a first
position spaced from the openings 598, 600 (as shown in FIG. 8) and
a second position closer to the openings 598, 600 (as shown in FIG.
9) the profiles of the openings 598, 600 will cause fluid to flow
in the direction of arrows 610, 612, and 614. More specifically, as
the diaphragm 596 transitions from the second position of FIG. 9
towards the first position of FIG. 8 (i.e. upward motion of the
diaphragm as viewed in the figures), fluid will be drawn into the
fluid channel through opening 598. In that regard, the expanding
profile of opening 598 between its first end 602 and second end 604
provides less resistance to fluid flow than the narrowing profile
of opening 600. Similarly, as the diaphragm 596 transitions from
the first position of FIG. 8 towards the second position of FIG. 9
(i.e. downward motion of the diaphragm as viewed in the figures),
fluid will be pushed out of the fluid channel through opening 600.
In that regard, the expanding profile of opening 600 between its
first end 606 and second end 608 provides less resistance to fluid
flow than the narrowing profile of opening 598. In this manner, the
oscillation of diaphragm 596 can be utilized to cause directional
fluid flow. Accordingly, in some embodiments this structural
arrangement is utilized in the context of bubble chambers of the
present disclosure. For example, in some instances, the diaphragm
596 is the diaphragm of a bubble chamber and the openings 598 and
600 are portions of an associated lumen or fluid channel. In that
regard, it is understood that the orientations of the openings 598
and 600 can be reversed to facilitate fluid flow in the opposite
direction, if desired.
[0111] Referring now to FIG. 10, shown therein is a diagrammatic
schematic view of a valve system 620 according to another
embodiment of the present disclosure. In that regard, valve system
620 is similar in many respects to valve system 580 described
above, but the valve system 620 includes check valves 552 and 564.
In that regard, check valves 552 and 564 operate in the same manner
as described above with respect to valve system 540. Further, the
bubble chambers 566 and 572 are associated with nozzle/diffuser
fluid channels, as described above with respect to valve systems
580 and 590. In other embodiments, however, at least one of the
bubble chambers 566 and 572 is not associated with a
nozzle/diffuser fluid channel.
[0112] Referring now to FIG. 11, shown therein is a diagrammatic
schematic view of a valve system 630 according to another
embodiment of the present disclosure. In that regard, valve system
630 is similar in many respects to valve system 580 described
above, but the valve system 630 includes check valves 548 and 560.
In that regard, check valves 548 and 560 operate in the same manner
as described above with respect to valve system 540. Further, the
bubble chambers 566 and 572 are associated with nozzle/diffuser
fluid channels, as described above with respect to valve systems
580 and 590. In other embodiments, however, at least one of the
bubble chambers 566 and 572 is not associated with a
nozzle/diffuser fluid channel.
[0113] Referring now to FIGS. 12-17, shown therein are aspects of a
valve system 640 according to another embodiment of the present
disclosure. In that regard, FIG. 12 is a diagrammatic schematic
view of the valve system 640, while FIGS. 13-17 are sequential
diagrammatic schematic views of the valve system illustrating
operation of the valve system. More specifically, FIG. 13 is a
diagrammatic schematic view of the valve system 640 in a first
orientation; FIG. 14 is a diagrammatic schematic view of the valve
system showing a transition from the first orientation illustrated
in FIG. 13 to a second orientation; FIG. 15 is a diagrammatic
schematic view of the valve system in the second orientation; FIG.
16 is a diagrammatic schematic view of the valve system showing a
transition from the second orientation illustrated in FIG. 15 to a
third orientation; FIG. 17 is a diagrammatic schematic view of the
valve system in the third orientation.
[0114] Referring more specifically to FIG. 12, the valve system 640
includes an adjustable valve 642. The adjustable valve 642 is
comprised of a housing 644 that defines a cavity 646 that contains
an electro-kinetic fluid (that is, a fluid compatible with and
well-suited for electro-kinetic pumping). A membrane or diaphragm
648 is coupled to the housing 644 such that the diaphragm defines
an upper boundary of the cavity 646. In that regard, the diaphragm
648 is formed of a material that is more flexible than the material
forming the housing 644 such that the diaphragm 648 is movable
between different positions based upon the amount of fluid within
the cavity 646. In some instances, the diaphragm 648 is formed of
silicone rubber, polyimide, a thin silicon membrane, Parylene, a
thin silicon nitride membrane, gold, Parylene/gold/Parylene
composite membranes and the like, and/or other suitable materials.
As the amount of fluid within the cavity 646 is increased, the
pressure within the cavity increases, which results in the
displacement of the diaphragm 648 away from the cavity (upwards as
viewed in FIG. 12). An exemplary displaced position of the
diaphragm 648 corresponding to an increased amount of fluid and
pressure within cavity 646 is illustrated in phantom. In some
instances, the adjustable valve 642 is implemented as a boss valve
(e.g., similar to the boss valve illustrated in FIGS. 18-20 and
described below).
[0115] In order to control the amount of fluid within the cavity
646 and, thereby, the relative position of the diaphragm 648, the
adjustable valve 642 is in communication with an electro-kinetic
fluid reservoir 650. The fluid reservoir 650 includes a housing 652
that defines a cavity 654 that also contains the electro-kinetic
fluid. In the present embodiment, the housing 652 is formed of a
relatively flexible material, such as Parylene, silicone rubber,
thin silicon membranes, Parylene/Au/Parylene composites, polyimide,
thin silicon nitride membranes, gold membranes and the like. In
some instances, the housing 652 is an expandable pouch or bag. In
that regard, the housing 652 is designed to inflate and deflate
depending on the amount of fluid received within cavity 654.
Accordingly, the housing defines a varying volume for cavity 654
during use. In some instances, the housing 652 is received within a
chamber that limits inflation of the housing. In that regard, the
chamber is defined by a material having an increased stiffness
and/or hardness compared to the material of the housing 652, in
some instances.
[0116] The cavity 646 of the adjustable valve 642 is in fluid
communication with the cavity 654 of the fluid reservoir 650. This
allows a flow of fluid between the cavities 646 and 654 such that a
desired amount of fluid is held within cavity 646 in order to
maintain the diaphragm 648 in a desired position. In that regard, a
lumen 656 extends from cavity 646 to a check valve 658. Check valve
658 allows fluid flow only in the direction away from cavity 646
and towards cavity 654. That is, check valve 658 prevents fluid
flow from cavity 654 towards cavity 646. A lumen 660 connects lumen
656 and check valve 658 to an electro-kinetic porous membrane 662.
A lumen 664 connects the electro-kinetic porous membrane 662 to
cavity 654. In that regard, in the illustrated embodiment lumen 664
serves as both an egress and ingress lumen for cavity 654.
[0117] In the illustrated embodiment, in addition to being in fluid
communication with lumen 660, lumen 664 and electro-kinetic porous
membrane 662 are also in fluid communication with lumen 668. Lumen
668, in turn, extends to a check valve 670. Check valve 670 allows
fluid flow only in the direction away from cavity 654 and towards
cavity 646. That is, check valve 670 prevents fluid flow from
cavity 646 towards cavity 654. A lumen 672 connects lumen 668 and
check valve 670 to cavity 646. Generally, the check valves 658, 670
can have any desired cracking pressure. As the function of the
check valves is to ensure that fluid flows in a particular, any
type of check valve or one way valve may be used, including, for
example, a flapper or Reed valve.
[0118] In one embodiment, with the intent to maintain pressure in
cavity 646 when desired, check valve 658 has a non-zero cracking
pressure approximately equal to the pressure required to maintain
membrane 648 in the maximum outward position meaning valve 642 is
fully closed. For example, such a pressure might be 100 mmHg with a
tolerance of about 5 mmHg. In this way pressure in cavity 646 is
maintained with zero energy applied to the system (i.e. no power
consumed by voltage supply 674) and thus the height of diaphragm
648 is maintained. If the pressure in cavity 646 is to be reduced
(diaphragm 648 lowered and thus valve 642 opened), then activation
voltage supply 674 creates a pressure gradient forcing fluid from
cavity 646 to cavity 654 through check valve 658 via flow channels
656, 660. Conversely, if it is desired to raise diaphragm 648, then
activation voltage supply 674 creates a pressure gradient forcing
fluid from cavity 654 to cavity 646 through check valve 670 via
fluid channels 668, 672. In this instance, check valve 670 has a
cracking pressure near zero (for example, 0.1 mmHg or lower).
[0119] The valve system 640 also includes a voltage source 674 that
is in electrical communication with the electro-kinetic fluid
within cavities 646 and 654. More specifically, electrodes 676 and
678 that are connected to the voltage source 674 are positioned in
electrical communication with the electro-kinetic fluid within the
cavities 646 and 654. While the electrodes 676 and 678 are shown as
being positioned within cavities 646 and 654, respectively, in
other embodiments one or more of the electrodes is outside of the
cavities. Generally, however, electrodes are positioned on either
side of the electro-kinetic porous membrane 662. For example, in
one embodiment, the electrodes 676 and 678 are both positioned in
fluid channel 664 where electrode 67 is positioned between fluid
channels 660, 668 and electro-kinetic porous membrane 662 and
electrode 678 is positioned in between electro-kinetic porous
membrane 662 and cavity 654. The electrodes 532, 534 are formed of
a conductive material, such as platinum (Pt), gold (Au), silver
(Ag), silver chloride (AgCl), iridium with a coating of oxide
(IrO.sub.2), carbon (e.g., thick-film, nano-porous, and/or
"aerogel" type carbon as used in super capacitors), copper, and/or
other conductive materials. In use, a voltage is applied across
electrodes 676, 678 in order to cause the flow of fluid across
electro-kinetic porous membrane 662. In that regard, the
electro-kinetic fluid received within the valve system 640 is
generally an aqueous solution with a neutral pH level. In some
instances, for efficient pumping, the pH of the electro-kinetic
fluid is chosen such that the zeta potential of the EK pump
material selected is at a maximum. Final trade-off could be driven
by biocompatibility (e.g. pH neutral to ocular fluids). Typical
ranges are pH 4-8 with a buffer capacity of 5-50 mM. The
electro-kinetic fluid is non-toxic with a low to medium
conductivity. In one instance, this fluid is deionized water.
[0120] The resulting electric field applied to the electro-kinetic
fluid by the electrodes 676, 678 is utilized to drive the fluid
through the porous membrane 662. In that regard, the relationship
between pressure buildup in the electro-kinetic fluid and the flow
rate of the fluid depends on the strength of the applied electric
field and the properties of the materials involved. In some
instances, the structures of the valve system 640 are formed of
glass, silica, frit material (e.g., sintered glass micro-beads),
porous polymers, and/or combinations thereof. In some particular
instances the structures of the valve system 640 are formed using
semi-conductor and/or MEMS manufacturing techniques. In that
regard, the structures are formed by interconnecting features of a
plurality of material layers. Further, in some instances a porous
polymer (e.g., PVDF with a 100 or 200 nm pore size) is used as the
electro-kinetic porous membrane 662. In some embodiments, a
suitable off-the-shelf filtration membrane is utilized as
electro-kinetic porous membrane 662.
[0121] Referring now to FIGS. 13-17, operation of the valve system
640 will be described. Referring more specifically to FIG. 13, the
valve system 640 is shown in a first orientation. In that regard,
the diaphragm 648 is shown in a neutral position. With the valve
system 640 in the first orientation, a positive voltage is applied
across electrodes 676 and 678. Referring now to FIG. 14, the valve
system 640 is shown transitioning from the first orientation
illustrated in FIG. 13 to a second orientation. In that regard, the
application of a positive voltage across the electrodes 676, 678
causes a positive electro-kinetic pressure that urges the
electro-kinetic fluid from cavity 654 through the electro-kinetic
porous membrane 662 (as indicated by arrow 680) and through check
valve 670 (as indicated by arrow 682) into cavity 646. The one-way
nature of check valve 658 prevents the flow of fluid through lumens
660 and 656 toward cavity 646. As the volume of fluid received
within cavity 646 increases as a result of the fluid flow, the
diaphragm 648 is displaced upward (as indicated by arrow 684)
towards a fully expanded position. Once the desired position of
diaphragm 648 is reached, the voltage source 674 decreases the
voltage applied to the electrodes 676, 678. In some instances, the
voltage source 674 is de-energized such that the applied voltage is
0.
[0122] Referring now to FIG. 15, the valve system 640 is shown in a
second, expanded orientation. In some instances, the expanded
orientation of FIG. 15 is a fully expanded position. The valve
system 640 is configured to maintain the expanded position of
diaphragm 648 without the application of a positive voltage (see
above discussion in reference to FIG. 12 regarding check valve
pressure and below discussion in reference to FIG. 17). In that
regard, backward flow of fluid from the cavity 646 into lumens 672
and 668 is prevented by check valve 670. Further, in some
embodiments the cracking pressure of the check valve 658 is greater
than or approximately equal to the maximum pressure occurring
within the cavity 646 that is associated with the fully expanded
position of the diaphragm 648. Accordingly, regardless of the
amount of displacement of the diaphragm 648, the check valve 658
will prevent the flow of fluid through lumens 656 and 660 towards
cavity 654. In this manner, the valve system 640 is able to
maintain the diaphragm in a fixed position without the application
of voltage from the voltage source 674. Accordingly, in some
instances, the valve system 640 only consumes power when moving
between different settings. Once the valve system 640 reaches the
desired setting, no additional power is needed to maintain the
valve system in the desired position.
[0123] With the valve system 640 in the second, expanded
orientation, a positive voltage may be applied across electrodes
676 and 678 to further expand the diaphragm 648 towards the fully
expanded position (in the same manner described above) or a
negative voltage may be applied across electrodes 676 and 678 to
retract the diaphragm 648. Referring now to FIG. 16, the valve
system 640 is shown transitioning from the second, expanded
orientation illustrated in FIG. 15 to a third orientation with the
application of a negative voltage. In that regard, the application
of a negative voltage across the electrodes 676, 678 causes a
negative electro-kinetic pressure (in addition to the negative
pressure provided by the fluid within cavity 646) that urges the
electro-kinetic fluid from cavity 646 through check valve 658 (as
indicated by arrow 686) and through the electro-kinetic porous
membrane 662 (as indicated by arrow 688) into cavity 654. The
one-way nature of check valve 670 prevents the flow of fluid
through lumens 672 and 668 toward cavity 654. As the volume of
fluid received within cavity 646 decreases as a result of the fluid
flow, the diaphragm 648 is displaced downward (as indicated by
arrow 690) towards a third, retracted orientation. Once the desired
position of diaphragm 648 is reached, the voltage source 674
increases the voltage applied through the electrodes 676, 678. In
some instances, the voltage source 674 is de-energized such that
the applied voltage is 0.
[0124] Referring now to FIG. 17, the valve system 640 is shown in
the third, retracted orientation. In some instances, the retracted
orientation of FIG. 17 is the neutral position of FIG. 13. Again,
the valve system 640 is configured to maintain the retracted
position of diaphragm 648 without the application of negative
voltage. In that regard, flow of fluid from the cavity 654 into
lumens 656 and 660 is prevented by check valve 658. Also, the fluid
pressure within cavity 646 will cause valve 670 to remain closed,
preventing the flow of fluid through lumens 668 and 672 towards
cavity 646. In this manner, the valve system 640 is able to
maintain the diaphragm in the retracted position without the
application of voltage from the voltage source 674. Again, in some
instances, the valve system 640 only consumes power when moving
between different settings such that no additional power is needed
to maintain the position of the diaphragm 648 once the valve system
640 reaches the desired setting.
[0125] In one particular embodiment, the cracking pressure of check
valve 658 is approximately 100 mmHg, the pressure required to set
the valve 642 at its maximum expansion state (i.e., diaphragm 648
displaced upwards to its maximum extent) is approximately 90 mmHg,
and the pressure between the check valves 658, 670 and the
electro-kinetic porous membrane 662 is approximately -20 mmHg when
pumping fluid out of cavity 646 towards cavity 654. Accordingly,
when the pressure between the check valves 658, 670 and the
electro-kinetic porous membrane 662 is driven to approximately -20
mmHg using voltage source 674 (as discussed below) while the valve
642 is in its maximum expansion state, the pressure difference
across valve 658 will be approximately 110 mmHg, which exceeds the
100 mmHg cracking pressure of the valve 658. Accordingly, fluid
will flow through the valve 658 until the pressure difference
across the valve 658 dips below the cracking pressure of 100 mmHg
for the valve. It is understood that these exemplary pressures are
for illustration of the function of the system and are not limiting
in any way. Rather, it is understood that a wide range of cracking
pressures, maximum expansion pressures, and/or driving pressures
are used within the context of the present disclosure. Further, it
is also understood that similar pressure concepts are utilized to
cause fluid to flow through valve 670 towards cavity 646. In that
regard, the cracking pressure of valve 670 is less than pressure
required to set the valve 642 at its maximum expansion state (i.e.,
diaphragm 648 displaced upwards to its maximum extent) and is less
than the cracking pressure of valve 658, in some embodiments. In
one instance, check valve 670 has a cracking pressure near zero
(for example, 0.1 mmHg or lower).
[0126] The valve system 640 can be selectively moved between
positions that obstruct fluid flow through an adjacent lumen (See,
for example, FIGS. 26 and 27) with selective application of
positive and/or negative voltages to the electro-kinetic fluid. In
that regard, the ability of the diaphragm 648 to be displaced
allows for a variable level of flow restriction through the lumen
by the varying how far into the lumen the diaphragm goes. In some
instances, the diaphragm 648 is movable between a position that
does not block the lumen at all (0% blockage), a position that
blocks the lumen completely (100% blockage), and positions
therebetween that partially block the lumen (0.01-99.9% blockage).
The particular range of lumen blockages provided by the valve
system 640 can be selected for particular uses and may include any
subset of lumen blockages between 0% and 100% blockage. In use, the
valve system 640 can restrict the amount of aqueous that enters the
drainage location and exits the anterior chamber. In some
instances, the valve system 640 controls the aqueous flow based on
readings from pressure sensor(s), such as P1, P2, and P3, as
described above. Controlling aqueous flow can reduce the chances of
hypotony after filtration surgery, maintain a suitable IOP, and/or
control the amount of stagnant aqueous in the drainage location.
When the drainage location is a subconjunctival bleb, controlling
the amount of stagnant aqueous in the bleb can help maintain proper
bleb morphology and reduce the amount of fibrosis. Too much
stagnant aqueous in a bleb can lead to fibrosis. It has been
postulated that fibroblasts form in stagnant aqueous and that too
much tension on the bleb wall (i.e., too high a pressure in the
bleb) can lead to bleb failure. Accordingly, the use of valves and
valve systems of the present disclosure, including valve system
640, can lead to proper bleb maintenance, which decreases the
chances of these deleterious side effects. In some instances, the
diaphragm 648 is repeatedly transitioned between an open position
and a closed position to cause a flow of fluid through an
associated lumen (i.e., the diaphragm is utilized to pump fluid).
In this manner, the valve system 640 can be utilized as a pump.
[0127] Referring now to FIGS. 18-20, shown therein are aspects of a
boss valve system 700 according to an embodiment of the present
disclosure. More specifically, FIG. 18 is a diagrammatic top view
of the boss valve system 700; FIG. 19 is a diagrammatic
cross-sectional side view of the boss valve system in a first
orientation; and FIG. 20 is a diagrammatic cross-sectional side
view of the boss valve system similar to that of FIG. 19, but
showing the boss valve system in a second orientation. As shown in
FIG. 18, the boss valve system 700 includes a housing 702 having an
opening 704, a boss 706, and an opening 708. In some embodiments,
the openings 704, 708 have a diameter between about 100 to 1,000
micrometers, while the boss 706 has a diameter between about 110 to
4,000 micrometers.
[0128] Referring now to FIGS. 19 and 20, the boss 706 includes a
diaphragm 710 positioned adjacent a chamber 712. In that regard, in
some instances the diaphragm 710 and chamber 712 are similar to or
identical to the diaphragms and associated cavities described above
with respect to previous valve systems. In that regard, it is
understood that any of previously described valve systems may be
implemented in boss valve system similar to that of FIGS. 18-20 in
some embodiments. In some embodiments, the diaphragm or membrane
710 has a diameter between about 500 to 5,000 micrometers a
thickness between about 0.1 to 15 micrometers and center deflection
between its most expanded position and its most retracted position
between about 10 to 250 micrometers.
[0129] As shown in FIGS. 19 and 20, the chamber 712 is bounded by
the diaphragm 710 such that as the pressure and/or volume of fluid
within chamber 712 are increased the diaphragm 710 will be
displaced in a downward direction in the orientation shown in FIG.
19. In that regard, FIG. 20 illustrates an exemplary displaced
position of the diaphragm 710. The diaphragm 710 is in
communication with a fluid channel that includes openings 704 and
708. In the illustrated embodiment, opening 708 serves as an inlet
and opening 704 serves as an outlet. In some instances, one or both
of the openings 704, 708 define a nozzle/diffuser structure to
facilitate the directional flow of fluid through the fluid channel.
As the diaphragm 710 is moved between a first position spaced from
the opening 708 (as shown in FIG. 19) and a second position closer
to the opening 708 (as shown in FIG. 20) fluid will flow through
the fluid channel defined by the housing. More specifically, as the
diaphragm 710 transitions from the second position of FIG. 20
towards the first position of FIG. 19 (i.e. upward motion of the
diaphragm as viewed in the figures), fluid will be drawn into the
fluid channel through opening 708. Similarly, as the diaphragm 710
transitions from the first position of FIG. 19 towards the second
position of FIG. 20 (i.e. downward motion of the diaphragm as
viewed in the figures), fluid will be pushed out of the fluid
channel through opening 704. In this manner, the movement of
diaphragm 710, which is oscillatory in some instances, can be
utilized to cause directional fluid flow. Generally, the position
of the diaphragm 710 relative to opening 708 can be adjusted to
control the amount of fluid flowing through the fluid channel. In
that regard, the diaphragm 710 is movable between a position that
does not block the fluid channel at all (0% blockage), a position
that blocks the fluid channel completely (100% blockage), and
positions therebetween that partially block the fluid channel
(0.01-99.9% blockage).
[0130] Referring now to FIGS. 21a, 21b, 22a, and 22b, shown therein
are aspects of a valve system 720 according to another embodiment
of the present disclosure. In that regard, FIG. 21a is a
diagrammatic top view of the valve system 720 illustrating fluid
flow in a first direction; FIG. 21b is a diagrammatic
cross-sectional side view of the valve system associated with fluid
flow in the first direction; FIG. 22a is a diagrammatic top view of
the valve system illustrating fluid flow in a second direction; and
FIG. 22b is a diagrammatic cross-sectional side view of the valve
system associated with fluid flow in the second direction.
[0131] As shown, the valve system 720 includes a housing 722 that
contains an adjustable valve 724, a fluid reservoir 726, an
electro-kinetic membrane 728, a check valve 730, and a check valve
732. In that regard, the valve system 720 is an exemplary
structural implementation of valve system 640 discussed above with
respect to a schematic diagram. For example, adjustable valve 724
may be similar to valve 642, fluid reservoir 726 may be similar to
fluid reservoir 650, electro-kinetic membrane 728 may be similar to
electro-kinetic porous membrane 662, and check valves 730 and 732
may be similar to check valves 658 and 670. In that regard, fluid
channels 734, 736, 738a, 738b, 739a, 739b, and 740 interconnect the
adjustable valve 724 and the fluid reservoir 726 through the
electro-kinetic membrane 728 and check valves 730, 732. It is
understood that the illustrated fluid channels 734, 736, 738a,
738b, 739a, 739b, and 740 are representative of the connections
between the components and, therefore, may include multiple lumens
and/or channels in some instances.
[0132] Accordingly, fluid can be moved through the fluid channels
between the fluid reservoir 726 and a chamber 742 of the valve 724
to adjust the relative position of a flexible membrane 744 of the
valve. In that regard, FIG. 21b shows the flexible membrane 744 in
an expanded position, while FIG. 22b shows the flexible membrane in
a retracted position. Though not explicitly shown, it is understood
that valve system 720 includes electrodes in communication with the
fluid within the fluid reservoir 726 and the chamber 742 of valve
724. In that regard, the electrodes may be formed within the fluid
reservoir 726 and the chamber 742 during manufacturing.
[0133] In that regard, the valve systems of the present invention
can be made using manufacturing techniques in which layers are
formed, for example by undergoing one or more steps that may
include deposition, patterning and etching processes, on a
substrate that forms part of the housing defining and/or containing
the valve system, including semiconductor and/or MEMS processing
techniques. In that regard, the housing is generally flat in some
embodiments. In other embodiments, the housing has a slight
curvature that accommodates the curvature of the eye. Generally,
the housing can be made of any of a number of different
biocompatible materials, including stainless steel, silicon, and/or
germanium. In some embodiments, the valve systems are manufactured
such that all or substantially all of the elements of the valve
system are located on, under, or embedded in a plate that extends
into the drainage location in a similar manner to some currently
available glaucoma drainage devices.
[0134] In FIG. 21a, flow arrows indicate the direction of liquid
transfer when the flexible membrane 744 is to be raised. Electronic
activation of the electro-kinetic membrane 728 provides a pressure
gradient that moves fluid from fluid reservoir 726 (lower portion
of chip as shown) through path 734 and the electro-kinetic membrane
728, through paths 736 and 738a, check valve 732, paths 739a and
740, and into the chamber 742 of valve 724 (upper portion of the
chip as shown in FIG. 21b). Note that check valve 732 only permits
flow in this direction. In FIG. 22a, flow arrows indicate the
direction of liquid transfer when the flexible membrane 744 is to
be lowered. Electronic activation of the electro-kinetic membrane
728 provides a pressure gradient that moves fluid from the chamber
742 of valve 724 (upper portion of the chip as shown in FIG. 22b)
through paths 740 and 739b, through check valve 730, through paths
738b and 736, through the electro-kinetic membrane 728, through
path 734, and into fluid reservoir 726 (lower portion of chip as
shown in FIG. 22b). Note that check valve 730 only permits flow in
this direction.
[0135] Referring now to FIGS. 23-25, shown therein are aspects of a
valve system 750 according to another embodiment of the present
disclosure. In particular, FIG. 23 is a diagrammatic
cross-sectional, exploded side view of layers of the valve system
750; FIG. 24 is a diagrammatic cross-sectional, assembled side view
of the valve system 750; and FIG. 25 is a diagrammatic top view of
the valve system 750.
[0136] Referring more specifically to FIG. 23, the valve system 750
includes three layers, a bottom layer 752, a middle layer 754, and
a top layer 756. Collectively, the layers 752, 754, and 756 define
two check valves 758 and 760 in accordance with the present
disclosure. In that regard, in some instances the check valves 758
and 760 are suitable for use as the check valves of the valve
systems described above. In some embodiments, the valve system
includes only one of the check valves 758 or 760. In other
embodiments, the valve system includes two check valves, but of the
same type (e.g., two valves similar to check valve 758 or two
valves similar to check valve 760). In some instances, the check
valves 758 and 760 are in communication with one another. In other
instances, the check valves 758 and 760 are not in communication.
The following description will describe the check valves 758 and
760 as being formed on the same layers 752, 754, and 756. However,
it is understood that the check valves 758 and 760 are formed on
different layers and/or on entirely separate chips in other
embodiments.
[0137] As shown in FIGS. 23 and 24, the bottom layer 752 defines an
opening 762 for valve 758 and an opening 764 for valve 760.
Further, the bottom layer 752 includes recesses 766 and 768 that
form a portion of a fluid channel associated with valve 758. The
bottom layer 752 also includes a recess 770 that forms a portion of
a fluid channel associated with valve 760. The middle layer 754
includes a pair of openings 772 and 774 that define a structure
776. In that regard, when assembled with the bottom layer 752, the
structure 776 is positioned over opening 762, while openings 772
and 774 are positioned over recesses 766 and 768, respectively. The
structure 776 performs as a check valve by preventing the flow of
fluid down through opening 762. In that regard, the structure 776
is a cantilevered spring or flap or spider valve in some instances
such that the structure 776 is displaced upwards away from opening
762 with the application of sufficient pressure.
[0138] The middle layer 754 also includes an opening 778 adjacent a
structure 780. In that regard, when assembled with the bottom layer
752, the opening 778 is positioned over recess 770 to define a
portion of the fluid channel while structure 780 is positioned over
opening 764. In that regard, structure 780 performs as a check
valve by preventing the flow of fluid down through opening 764. In
that regard, in some instances the structure 780 is a flexible
membrane that is displaceable upwards away from the opening 764
with the application of sufficient pressure. In some instances, the
use of a flexible membrane in combination with the spring/flap
structure allows the two check valves 758 and 760 to be formed with
a single middle layer. In contrast, where two spring/flap
structures are used, in some instances two middle layers are
necessary. In this exemplary embodiment, check valve 758 is shown
as a cantilevered spring valve, while check valve 760 is shown as a
flexible membrane. While the valves 758 and 760 have been described
as having different structures (e.g., cantilevered versus
membrane), it is understood that each of the valves 758 and 760 may
have any suitable structure, including the same structure as the
other valve.
[0139] The upper layer 756 includes a recess 782, a recess 784, and
a recess 786. In that regard, when assembled with the middle layer
754, the recess 782 is positioned over openings 772 and 774 as well
as structure 776. Accordingly, the recess 782 defines a portion of
the fluid channel and also provides space to allow the deflection
or displacement of the structure 776 upwards away from the opening
762. Also, when assembled with the middle layer 754, the recess 784
is at least partially positioned over opening 778 to define a
portion of the fluid channel associated with valve 760. Further,
recess 786 is positioned over structure 780. In that regard, the
recess 786 provides space to allow the displacement of the
structure 780 upwards away from the opening 764. For check valves
758, flow enters opening 762 and exits via recess 782. Similarly,
for check valve 760, flow enters opening 764 and exits via recess
784.
[0140] As shown in FIGS. 24 and 25, when the layers 752, 754, and
756 are assembled the valve system 750 forms the two check valves
758 and 760. In that regard, check valve 758 generally allows fluid
flow in a direction opposite to the direction of fluid flow allowed
by check valve 760, as indicated by the fluid flow arrows.
Generally, the recesses and openings within the layers 752, 754,
and 756 may be formed using any suitable manufacturing techniques.
In some particular instances, the recesses and openings are formed
by etching a substrate (e.g., semiconductor (such as silicon and/or
germanium), glass, polymeric, and/or other suitable substrate
material). In that regard, it is understood that the three-layer
layout of FIGS. 23 and 24 is provided for exemplary purposes only
and in no way limits the number of layers that may be utilized to
form the valve systems of the present disclosure. Generally, any
number of layers may be utilized to form a valve. However, in some
instances it is desirable to keep the number of layers to a minimum
in order to reduce the overall size and/or thickness of the
resulting device. Further, it is understood that where a valve
system includes multiple valves that each of the valves may be
formed using the same or a different number layers as another of
the valves.
[0141] Referring now to FIGS. 26 and 27, shown therein are aspects
of a valve system 800 according to another embodiment of the
present disclosure. In that regard, FIG. 26 shows the valve system
800 interfacing with a lumen of a glaucoma drainage device in a
first orientation, while FIG. 27 shows the valve system interfacing
with the lumen of the glaucoma drainage device in a second
orientation. Generally speaking, the valve system 800 represents
any of the valve systems of the present disclosure that may be
utilized to control the flow of fluid through a lumen or tube
through the control of a displaceable membrane of the valve system.
In that regard, the valve system 800 includes an adjustable valve
802. The adjustable valve 802 includes a housing 804 that defines a
cavity 806 that contains a fluid. A flexible membrane or diaphragm
808 is coupled to the housing 804 such that the diaphragm defines
an upper boundary of the cavity 806. In that regard, the diaphragm
808 is formed of a material that is more flexible than the material
forming the housing 804 such that the diaphragm 808 is movable
between different positions based upon the amount of fluid and/or
pressure within the cavity 806.
[0142] In order to control the amount of fluid within the cavity
806 and, thereby, the relative position of the diaphragm 808, the
adjustable valve 802 is in communication with a fluid reservoir
810. In some instances, the fluid reservoir 810 defines a constant
volume reservoir. In other instances, the fluid reservoir 810 is
flexible such that the volume of the reservoir changes during
operation of the valve system. Generally, however, the fluid
reservoir 810 contains fluid that is transferred between the fluid
reservoir and the cavity 806 through fluid communication channels
812 and 814. In that regard, it is understood that the fluid
communication channels 812 and 814 are one way channels in some
instances. For example, in some instances channel 812 facilitates
the flow of fluid from fluid reservoir 810 to cavity 806, while
channel 814 facilitates the flow of fluid from cavity 806 to fluid
reservoir 810. In that regard, the channels 812, 814 may include
features (e.g., check valves, nozzles/diffusers, etc.) to encourage
fluid flow in a particular direction and prevent fluid flow in the
opposite direction.
[0143] In use, the diaphragm 808 is movable between positions that
occupy varying amounts of a channel or lumen 820 of a drainage
structure 822. In some instances, the drainage structure is a
drainage tube of a glaucoma drainage device. In that regard, the
relative position of the diaphragm 808 within the lumen 820
determines the amount of fluid flow through the drainage structure.
For example, in some instances the diaphragm 808 is movable between
a position that does not block the lumen at all (0% blockage), a
position that blocks the lumen completely (100% blockage), and
positions therebetween that partially block the lumen (0.01-99.9%
blockage). The particular range of lumen blockages provided by the
valve system 800 can be selected for particular uses and may
include any subset of lumen blockages between 0% and 100% blockage.
As shown in FIGS. 26 and 27, the diaphragm 808 is movable between a
first position that occupies very little of the cross-sectional
area of lumen 820 (e.g., less than 10%), as shown in FIG. 26, and a
second position that occupies substantially all of the
cross-sectional area of lumen 820 (e.g., more than 95%), as shown
in FIG. 27. By controlling the position of the diaphragm 808 within
the lumen 820, the corresponding fluid flow through the drainage
structure 822 can likewise be controlled.
[0144] In use, the valve systems of the present disclosure can
actively pump fluid at night while the patient is sleeping.
Typically, a glaucoma patient's IOP is highest in the morning (and
IOP can fluctuate during the night as well). Using an IOP sensor to
control the valves/pumps of the present disclosure can help to
maintain proper IOP during the night. In that regard, a patient may
wear a mask or have a device nearby that provides power to the
valve/pump. Accordingly, in some instances, the pump and/or valve
can be operated to maintain a desirable IOP using power from the
nearby external device. When the patient awakens, the valve/pump of
the glaucoma drainage device can be set for daytime operation that
consumes much less power. For example, active pumping can occur at
night when power consumption is of little concern (i.e., when a
supply of energy from an external device is provided) and minimal
or no pumping can occur during the day (i.e., when a supply of
energy from an external device is not provided). In one example,
the pump operates while the patient sleeps until the
subconjunctival bleb volume is expelled into the eye socket. During
this time, the drainage area may temporarily be blocked, forcing
more aqueous humor to flow via the natural outflow path until the
IOP rises to a threshold value, at which time the drainage area
(e.g. subconjunctival space) is re-opened. By emptying the bleb at
night, the flow from the anterior chamber into the vacant bleb
space during the day provides drainage with little or no back
pressure, which allows for a target IOP to be set and maintained.
In that regard, the valves/pumps of the present disclosure can be
used to maintain the IOP at or near the target IOP.
[0145] From the above, it may be appreciated that the present
disclosure provides valve systems that can be controlled by an IOP
sensor system to control fluid flows within a glaucoma drainage
device. In that regard, as described above, in some instances
operation of the valve systems of the present disclosure
facilitates a pumping of fluid from one location to another.
Accordingly, in such instances the valve systems of the present
disclosure may also be referred to as a pump or pump system. In
some embodiments, the valve systems of the present disclosure are
controlled using electrolysis and/or electro-kinetic fluid flows.
Other embodiments, variations, and combinations of features will be
apparent to those skilled in the art from the foregoing description
and accompanying drawings. Accordingly, it is intended that the
examples provided in the description and drawings be considered as
exemplary only, with a true scope and spirit of the invention being
indicated by the following claims.
* * * * *