U.S. patent application number 10/515999 was filed with the patent office on 2005-12-08 for shunt and method treatment of glaucoma.
Invention is credited to Grahn, Bruce Harold, Stilling, Denise Sharon, Storey, Eric Shad.
Application Number | 20050273033 10/515999 |
Document ID | / |
Family ID | 29584589 |
Filed Date | 2005-12-08 |
United States Patent
Application |
20050273033 |
Kind Code |
A1 |
Grahn, Bruce Harold ; et
al. |
December 8, 2005 |
Shunt and method treatment of glaucoma
Abstract
This invention provides a shunt for implantation between the
anterior chamber of the eye and the epithelial-lined space through
the frontal sinus bone of a patient for the treatment of glaucoma.
The shunt includes a tube having a length sufficient to span the
distance between the anterior chamber of the eye and the
epithelial-lined space of the patient, the tube having an open
anterior chamber end and a closed epithelial-lined space end, and a
seal device associated with the tube between the anterior chamber
and epithelial-lined space ends, for sealing a hole in the frontal
sinus bone, and for anchoring the tube against movement from the
frontal sinus bone. The shunt also includes a fluid pressure
openable valve in the tube, located at or near the epithelial-lined
space sinus end, allowing for controlled flow of aqueous humor
through the tube when implanted. The invention also extends to a
method of treating glaucoma in a patient by surgically implanting
the shunt between the anterior chamber of the eye and the frontal
sinus.
Inventors: |
Grahn, Bruce Harold;
(Saskatchewan, CA) ; Storey, Eric Shad; (Baton
Rouge, LA) ; Stilling, Denise Sharon; (Saskatchewan,
CA) |
Correspondence
Address: |
GREENLEE WINNER AND SULLIVAN P C
4875 PEARL EAST CIRCLE
SUITE 200
BOULDER
CO
80301
US
|
Family ID: |
29584589 |
Appl. No.: |
10/515999 |
Filed: |
April 14, 2005 |
PCT Filed: |
May 29, 2003 |
PCT NO: |
PCT/CA03/00774 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60383599 |
May 29, 2002 |
|
|
|
Current U.S.
Class: |
604/9 ;
604/8 |
Current CPC
Class: |
A61M 27/002 20130101;
A61F 9/00781 20130101; A61M 2210/0612 20130101; A61F 9/0017
20130101; A61M 39/22 20130101 |
Class at
Publication: |
604/009 ;
604/008 |
International
Class: |
A61M 005/00 |
Claims
We claim:
1. A shunt for implantation between the anterior chamber of the eye
and the epithelial-lined space through the frontal sinus bone of a
patient for the treatment of glaucoma, comprising: a tube having a
length sufficient to span the distance between the anterior chamber
of the eye and the epithelial-lined space of the patient, the tube
having an open anterior chamber end and a closed epithelial-lined
space end; a seal device associated with the tube between the
anterior chamber and epithelial-lined space ends, for sealing a
hole in the frontal sinus bone, and for anchoring the tube against
movement from the frontal sinus bone; and a fluid pressure openable
valve in the tube, located at or near the epithelial-lined space
sinus end, allowing for controlled flow of aqueous humor through
the tube when implanted.
2. The shunt of claim 1, wherein the epithelial-lined space is the
frontal sinus, and the closed end of the tube is thus the frontal
sinus end.
3. The shunt of claim 2, wherein the pressure openable valve is a
longitudinal slit in the tube, and one or more ligature devices
around the tube overlying or adjacent the slit such that adjustment
of the one or more ligature devices adjusts fluid flow through the
valve.
4. The shunt of claim 2, wherein the shunt further comprises a
reservoir located at the closed frontal sinus end of the tube, said
reservoir having a side wall forming one or more apertures through
which fluid can flow from the tube, and wherein the pressure
openable valve is located in the reservoir.
5. The shunt of claim 4, wherein the pressure openable valve
comprises a pair of spaced apart discs connected together by a
spring member, the disc facing the anterior chamber end being
apertured to allow the valve to open with a predetermined fluid
flow pressure from the anterior chamber end.
6. The shunt of claim 5, wherein the pressure openable valve is a
tapered nipple type valve.
7. The shunt of claim 5, wherein the pressure openable valve is a
butterfly type valve.
8. The shunt of any preceding claim, wherein the seal device
comprises a widened portion of the tube, or a pliable spool-shaped
plug fixed to the tube and through which the tube is threaded, said
plug having upper and lower pliable flanges which seal on either
side of the hole in the frontal sinus bone and which prevent
movement of the plug relative to the frontal sinus bone, the upper
flange being anterior chamber facing and being sufficiently pliable
to be slid through the hole in the frontal sinus bone.
9. The shunt of any preceding claim, wherein the sealing device or
plug bends the tube through an angle sufficient to prevent kinking
of the tube as it is implanted between the anterior chamber and the
frontal sinus.
10. The shunt of claim 8, wherein the sealing device or plug bend
the tube through an angle of between 80 and 100.degree..
11. A method of treating glaucoma in a patient, comprising: forming
a hole from the exterior into the epithelial-lined space of the
patient; surgically implanting through the hole, between the
anterior chamber and the epithelial-lined space, a shunt having a
fluid pressure openable valve; and draining aqueous humor from the
anterior chamber through the shunt to the epithelial-lined
space.
12. The method of claim 11, wherein the epithelial-lined space is
the frontal sinus, and the hole is formed in the frontal sinus
bone.
13. The method of claim 12, wherein the shunt includes a tube
having an open anterior chamber end and a closed frontal sinus end,
and wherein the valve is located at the frontal sinus end, allowing
for controlled flow of aqueous humor through the tube when
implanted.
14. The method of claim 13, wherein the pressure openable valve is
a longitudinal slit in the tube, and one or more ligature devices
around the tube overlying or adjacent the slit such that adjustment
of the one or more ligature devices adjusts fluid flow through the
valve.
15. The method of claim 13, wherein the shunt further comprises a
reservoir located at the closed frontal sinus end of the tube, said
reservoir having a side wall forming one or more apertures through
which fluid can flow from the tube, and wherein the pressure
openable valve is located in the reservoir.
16. The method of claim 15, wherein the pressure openable valve
comprises a pair of spaced apart discs connected together by a
spring member, the disc facing the anterior chamber end being
apertured to allow the valve to open with a predetermined fluid
flow pressure associated with glaucoma from the anterior chamber
end.
17. The method of claim 16, wherein the pressure openable valve is
a tapered nipple type valve.
18. The method of claim 16, wherein the pressure openable valve is
a butterfly type valve.
19. The method of any preceding claim, wherein the shunt further
comprises a seal device between the anterior chamber and frontal
sinus ends of the tube, for sealing the hole in the frontal sinus
bone, through which the tube is inserted, and for anchoring the
tube against movement from the frontal sinus bone.
20. The method of claim 19, wherein said seal device comprises a
widened portion of the tube, or a pliable spool shaped plug fixed
to the tube and through which the tube is threaded, said plug
having upper and lower pliable flanges which seal on either side of
the hole in the frontal sinus bone and which prevent movement of
the plug relative to the frontal sinus bone, the upper flange being
anterior chamber facing and being sufficiently pliable to be slid
through the hole in the frontal sinus bone.
21. The method of any preceding claim, wherein the sealing device
or plug bends the tube through an angle sufficient to prevent
kinking of the tube as it is implanted between the anterior chamber
and the frontal sinus.
19. The shunt of claim 21, wherein the sealing device or plug bend
the tube through an angle of between 80 and 100.degree..
Description
FIELD OF INVENTION
[0001] The present invention relates to a method and device for
controlling aqueous humor flow from the anterior chamber of the eye
in the treatment of glaucoma.
BACKGROUND OF THE INVENTION
[0002] Glaucoma is a medical condition in which the intraocular
pressure of the eye increases. The anterior chamber, the cavity
located between the cornea and lens, is filled with a fluid called
aqueous humor. The aqueous humor drains from the anterior chamber
to the venous system through the canals of Schlemm and is replaced
continuously by secretions from the ciliary body. Glaucoma occurs
when aqueous humor does not drain properly from the anterior
chamber, causing an increase in intraocular pressure, closure of
surrounding blood vessels, and damage to the retina and optic
nerve. This condition, left untreated, can be very painful and lead
to blindness. It is estimated that 65 million people world-wide
suffer from this condition (Glaucoma Research Foundation, 2002).
Animals can also be affected by this condition. It is estimated
there are 65 million dogs in North America, of which approximately
1.3 million will develop glaucoma.
[0003] Closed-angle glaucoma occurs when the iris becomes misshapen
and blocks the canals of Schlemm. The underlying cause of
open-angle glaucoma is a blockage within the canals. About 3
million people in the United States are afflicted with open-angle
glaucoma (Glaucoma Research Foundation, 2002). Secondary glaucoma,
either open- or closed-angle, can be caused by injury, abnormal
structures, inflammation, tumours, certain drugs, or diseases
(Moffett et al, 1993).
[0004] Current treatments consist of medications, laser surgery and
implantable drainage devices (Glaucoma Research Foundation, 2002).
Medications, often in the form of eye drops, work to decrease
intraocular fluid production, increase fluid drainage, or both.
These medications are associated with side effects, including
burning sensations in the eye, headaches, cardiac fluctuations and
blurred vision. The administration of medications for the treatment
of animals is difficult and ineffective. Laser surgery is used to
open the fluid draining channels or correct structures in the eye.
Multiple surgeries are often required, and medication is normally
still used to help control intraocular pressure post-surgery. There
is also the risk of allowing too much fluid to drain from the
anterior chamber, resulting in hypotony and flattening of the
eye.
[0005] Implants have also been used in the treatment of glaucoma.
These implants drain aqueous humor from the anterior chamber into
mesenchymal or subconjunctival tissues surrounding the eye. The
aqueous humor of eyes afflicted with glaucoma has a relatively high
concentration of cytokines. Cytokines are proteins that mediate the
generation of an immune response. Implants that drain aqueous humor
into tissues surrounding the eye induce scarring in such tissues,
which scarring ultimately inhibits absorption of fluid from the
shunt. Consequently glaucoma recrudesces and visual impairment
redevelops.
[0006] Current drainage implants are classified as either
restrictive or non-restrictive flow devices (Gal, 1999).
Non-restrictive flow devices, such as the Molteno drainage implant,
rely on the formation of fibrous tissue to slow the drainage of
fluid from the eye. These implants require at least two invasive
surgical procedures. The initial surgery is required to implant the
device. Fibrous tissue generally takes several weeks to form,
making it necessary to clamp or tie the device to limit fluid
drainage and prevent hypotony. A second surgery is required to
unclamp or untie the device once fibrosis has occurred. Restrictive
flow devices, such as the Krupin Eye Disk, are designed with
components that respond to fluid pressure, see for example U.S.
Pat. No. 5,454,796, issued Oct. 3, 1995 to Krupin, and U.S. Design
Pat. Des. 356,867 issued Mar. 28, 1995 to Krupin. When pressure in
the drainage tube exceeds a certain limit, the component, or valve,
will open and allow fluid to drain. Several problems have occurred
with these devices. First, it is difficult to calibrate the valve
to maintain an optimal intraocular pressure, and often leads to
hypotony. Second, the formation of fibrous tissue can occlude the
valve and render the drainage device useless. A similar restrictive
flow device is disclosed in U.S. Pat. Nos. 6,142,969 and 6,007,510,
issued to Nigam.
[0007] The frontal sinus 16 is an epithelium-lined cavity which is
not affected by cytokines. Studies by Cullen et al., with a shunt
implanted in dogs between the anterior chamber and the frontal
sinus showed no evidence of bacterial movement from the frontal
sinus 16 to the eye through this device (see Cullen et al,
1998).
[0008] Although somewhat successful in less severe cases, the prior
art implant devices, while successful in the short term, are not
effective for long-term management of glaucoma due to occurrence of
hypotony or more difficult forms of glaucoma. More effective
treatment regimes are needed.
SUMMARY OF INVENTION
[0009] To overcome the difficulties induced by fibrosis blocking
the valve or drainage tube and the scarring invoked by the cytokine
response, the inventors have developed a shunt device and method of
treatment for glaucoma that diverts aqueous humor from the anterior
chamber to an epithelial-lined space. While the method and device
have been successfully demonstrated with dogs, in which the shunt
was implanted between the anterior chamber of the eye and the
frontal sinus, the invention has application for the treatment of
glaucoma in all species of animals, including humans, and to other
epithelial-lined spaces besides the frontal sinus.
[0010] The term "epithelial-lined space", as used herein and in the
claims includes epithelial and epithelial-lined spaces, including
the frontal sinus, maxillary sinus, nasal sinus, other respiratory
sinuses or spaces, subdural space, and meningeal cavity.
[0011] Broadly, the invention provides a shunt for implantation
between the anterior chamber of the eye and the epithelial-lined
space through the frontal sinus bone of a patient for the treatment
of glaucoma. The shunt includes a tube having a length sufficient
to span the distance between the anterior chamber of the eye and
the epithelial-lined space of the patient, the tube having an open
anterior chamber end and a closed epithelial-lined space end, and a
seal device associated with the tube between the anterior chamber
and epithelial-lined space ends, for sealing a hole in the frontal
sinus bone, and for anchoring the tube against movement from the
frontal sinus bone. The shunt also includes a fluid pressure
openable valve in the tube, located at or near the epithelial-lined
space sinus end, allowing for controlled flow of aqueous humor
through the tube when implanted.
[0012] The invention also broadly provides a method of treating
glaucoma in a patient, comprising (a) forming a hole from the
exterior into the epithelial-lined space, for example in the
frontal sinus bone, of the patient; (b) surgically implanting
through the hole, between the anterior chamber and the
epithelial-lined space, a shunt having a fluid pressure openable
valve; and (c) draining aqueous humor from the anterior chamber
through the shunt to the epithelial-lined space. The shunt
preferably includes a tube having an open anterior chamber end and
a closed epithelial-lined space end, and wherein the valve is
located at the frontal sinus end, allowing for controlled flow of
aqueous humor through the tube when implanted.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 illustrates the shunt of the present invention
implanted in a dog, with portions of the eye being cut away to
illustrate placement of the shunt between the anterior chamber and
the frontal sinus;
[0014] FIG. 2 is a sectional view of the shunt implanted in the
eye, better illustrating the anterior chamber placement.
[0015] FIG. 3 is a sectional view of the shunt threaded through the
anchoring sealing device.
[0016] FIG. 4 is a sectional view of the shunt showing the
anchoring sealing device in place in the hole in the frontal sinus
bone.
[0017] FIG. 5 is a partial perspective view of the shunt showing
the slit valve and the ligatures used to adjust and control flow of
aqueous humor through the valve.
[0018] FIG. 6 is a schematic side sectional view of a second
embodiment of a shunt of the present invention, illustrating a
drainage reservoir housing for alternate valve devices.
[0019] FIG. 7 is an a schematic side sectional view of a third
embodiment of a shunt of the present invention, illustrating a
drainage reservoir for housing alternate valve devices, which
drainage reservoir also functions as the sealing device.
[0020] FIG. 8 is a perspective view, partially cut-away, showing a
tapered nipple plug type valve within the reservoir chamber of
either FIGS. 7 and 8.
[0021] FIG. 9 is a perspective view, partially cut-away, showing
the tapered nipple plug valve of FIG. 8 in the open position.
[0022] FIG. 10 is a perspective view of the taper nipple plug valve
unit of FIGS. 8 and 9.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The shunt of the present invention, shown generally at 10 in
the Figures is shown as designed for implantation between the
anterior chamber and the frontal sinus, however, the shunt has
application for implantation to other epithelial-lined spaces,
including the maxillary sinus, nasal sinus, other respiratory
sinuses or spaces, subdural space, and meningeal cavity.
[0024] The details of a first embodiment of the shunt 10 are best
shown in FIGS. 3-5, while the placement of the shunt 10 in a dog is
shown in FIGS. 1 and 2. The shunt 10 consists of a tube 12, made of
a biocompatible material such as silicone. The length of the tube
required is dependent on the species, but is of sufficient length
to reach the distance between the anterior chamber 14 and the
frontal sinus 16, through the frontal sinus bone 18, of the given
animal species. The tube 12 thus has a frontal sinus end 20 and an
anterior chamber end 22. The tube 12 is threaded through a
sutureless sealing device 24, which seals around the hole 25 in the
frontal sinus bone 18. The sealing device 24 is located close to
the frontal sinus end 20 of the tube 12. This acts to hold the tube
12 in place as well as prevents it from kinking. A valve device 26
is provided at or near the frontal sinus end 20 of the tube 12
(i.e., when implanted the valve is on the sinus side of the frontal
sinus bone). The sealing device 24 also functions to prevent serum
and clots from exuding from the exposed bone 18 and from
subcutaneous tissues within the frontal sinus and into the valve
device 26. In FIGS. 1 and 3, the valve device 26 is shown to be of
a slit valve type, formed by constructing a slit 28 in the frontal
sinus end 20 of the tube 12 approximately parallel to the
longitudinal axis of the tube 12. This frontal sinus end 20 is
inserted into the frontal sinus 16 and held in place with the
sealing component 24, which straddles the frontal sinus bone 18 and
anchors the tube against movement in either direction. The tube 12
is then tunnelled subcutaneously towards the eye and into the
anterior chamber 14. Surgical implantation of the shunt 10 is more
fully explained below.
[0025] The shunt will generally have a length ranging from 30 to
150 mm, and may be trimmed to length during surgery. However, the
shunt can be made to fit any species of animal (including humans)
by trimming any excess length from the anterior chamber end 22. The
shunt is generally formed from flexible, biocompatible materials
such as silicone, glass, medical grade acrylics, plastic, or metal
manufactured parts, with silicone or any similar biocompatible,
flexible material being most preferred. One advantage of the
present invention is that the tube 12 of the shunt 10 can be formed
from tubing having internal and external diameters that can be
varied according to the patient species together with the surgeon's
preference and/or the surgeon's skill. The dimensions are affected
by the space available in a particular patient's eye between the
cornea and the lens. The tube 12 should be sized so as to be fitted
into such space in such a fashion that the anterior chamber end 22
does not contact the iris, lens or cornea. While not being
limiting, exemplary dimensions for the shunt of the present
invention for implantation in dogs, taking into account the
ordinary skill of a surgeon, are as follows. For the tube portion
12, flexible tubing (such as silastic tubing) ranging from 0.25 to
0.64 mm inner diameters and 0.6 to 0.14 mm outer diameters with a
wall thickness from 0.2 to 0.64 mm are optimal.
[0026] The method and shunt 10 of the present invention allows for
the control of aqueous humor flow from the valve device 26 by means
of a simple adjustment procedure, explained more fully below. A
major constraint of prior art glaucoma shunts, the control of
intraocular pressure via fluid flow from valves, is addressed with
the present invention in that the flow of aqueous humor is
controlled by using an adjustable valve, or by associating a flow
control device with a valve. As best shown in FIG. 5, flow
adjustment through the slit 28 is provided by means of one or more
ligature devices 30. The ligature devices 30 may be formed from
O-rings, D-rings, C-clamps, sutures, or circumferential sutures
formed of a biocompatible material, which are placed or tied around
the tube 12 over and/or adjacent the slit 28. These ligature
devices 30 tighten the slit 28, allowing less fluid to escape from
the tube 12 and drain from the anterior chamber 14. The addition or
removal of these ligature devices 30 to control flow can be made by
a simple skin incision above the frontal sinus 16, which also
allows for easy removal of the shunt 10 (more fully described
below). Hydrostatic pressures of aqueous humor of glaucoma-affected
patients can vary among species and idiotypically among patients.
Also, rates of aqueous fluid of different species vary
significantly. The easy adjustment of the valve device 26 allows
this shunt 10 to be used in the treatment of various species, as
well as each individual within a species.
[0027] The slit 28 will generally be about 0.5 to 2.0 mm long, and
oriented approximately parallel to the longitudinal axis of the
tube 12. The slit 28 is preferably perpendicular to the tangent of
the tube wall. Variability in the length of the slit, the number of
slits, the number of ligature devices and the positioning of
ligature devices in relation to the slit provides flexibility
sufficient to permit adjustment for use with various species, as
well as various hydrostatic pressures of aqueous humor.
[0028] As shown in FIG. 5, the ligature devices 30 around the tube
12, are mounted circumferentially around the longitudinal axis of
the slit 28 and snug enough to slightly indent the tube 12 without
disturbing the orientation of the slit. The ligature devices 30 are
formed of a biocompatible material, with metal C-shaped clamps, and
plastic, silicone, or rubber round O-rings, being most preferred.
These preferred ligature devices are less prone to surgeon error
than sutures in that they can be sized such that they do not
excessively compress the valve walls and can be pre-placed at one
or both ends of the slit 28. During surgical placement, these
ligature devices 30 are slidably moved into variable positions
along the length of the slit 28, and the intraocular pressure
(fluid pressure indicative of glaucoma operative to open valve) is
measured to ensure a desired intraocular pressure will open the
valve device 26. Multiple ligature devices, up to 3/mm, have been
found to provide flexibility that allows the surgeon to finely
adjust valve tension and aqueous flow rates through the valve
device 26.
[0029] The sealing device 24 can take a variety of forms, such as a
widened portion (not shown) of the tube 12, a widened reservoir
plug as shown in FIG. 7, or a spool-shaped plug type seal as shown
in FIGS. 3 and 4. It is functional to seal the shunt 10 against the
hole 25 in the frontal sinus bone 18, and to anchor the shunt
against movement relative to the bone 18 once implanted. The
sealing device also bends the tube 12 though an angle sufficient to
ensure that the valve device 26, when the shunt 10 is implanted, is
wholly within the frontal sinus and maintained in the space (not
abutting the frontal sinus epithelium. For most species of
patients, an bending angle of 80 to 100.degree. is desired, so as
to maintain the most desired ingress and egress angle of the shunt
between the frontal sinus 16 and the anterior chamber 14. This best
positions the shunt 10 and avoids narrowing of the lumen of the
tube 12 or kinking of the tube 12. In one embodiment designed for
dogs, an angle of about 90.degree. was used.
[0030] The sealing device is most preferably a molded, spool-shaped
(grommet-like) plug 32, attached to the tube 12 and having an
central bore 34 sized to fit snugly around the tube 12. The plug
may be manufactured by carving a wax or wooden mold, positioning
the tube 12 in the mold at the desired ingress and egress angles,
flooding the mold with liquid silicone, allowing it to set and
removing the plug from the mold. The plug 32 has a central portion
36 joined to and an upper flange or lip (anterior chamber facing)
38 and a lower flange or lip (frontal sinus facing) 40. The flanges
38, 40 have a widened diameter relative to the diameter of the
central portion 36. Biocompatible materials for the plug are
silicone (a preferred embodiment) and rubber, plastic, glass, or
metal components. At least the lower flange 40, which is frontal
sinus facing, is made of a viscoelastic material such as silicone,
to enable it to be compressed and forced through the hole 25 in the
sinus bone 18. As mentioned above, the plug 32 bends the tube 12
though about an 80 to 100.degree. angle.
[0031] The shunt 10 should enter the anterior chamber 10-25 degrees
anterior to the limbal plane to avoid contact with the iris,
crystalline lens, or corneal endothelium. The trephine hole 25 of
the frontal sinus 16 is best situated approximately perpendicular
to the frontal bone 18. The tube 12 should enter and leave the at
plug 32 at about 90.degree. (i.e., bend the tube through about
90.degree.), but curve gently within the central bore 34 of the
plug 32, to decrease the potential for occlusion of the shunt 10 by
kinking the tube 12 or allowing trapping of fibrin clots within
this turn of the tube 12. The frontal sinus plug 32 should be
compressible to allow the lower flange 40, having a diameter
slightly larger than the trephined hole 25, to be introduced into
the frontal sinus (preventing unintentional egression of the shunt
10), and providing pressure against the bony walls of the trephined
hole 25 to stop hemorrhage from the bone 18 and to stop fibrin and
blood from collecting around the valve device 26.
[0032] Without being limiting, in one embodiment of the shunt
designed for dogs, the center portion 36 has a diameter of about
0.25-1.5 mm, which is approximately equal to the bore dimensions of
the trephined hole 25, and approximately 0.1 mm shorter than the
thickness of the bone 18 (1-2.5 mm), to create a tight sealing fit
to prevent haemorrhage from the bone 18 that may drain onto the
valve device 26. The external diameter of the flanges 38, 40 are
about 0.1-0.6 mm greater than the outside diameter of the tube 12,
and at least twice the diameter of the trephined hole 25 to prevent
complete ingress into the frontal sinus 16.
[0033] As indicated above, the shunt of the present invention, and
its parts, are formed from biocompatible materials, that is
materials which are biologically non-reactive and non-toxic to the
patient. Examples are silicone (sialastic tubing), glass, medical
grade plastic and some metals.
[0034] Second and third embodiments of the shunt 10 are shown in
FIGS. 6-10. In FIG. 6, the valve device 26 is shown to include a
drainage reservoir 42 housing a valve element (not shown). In FIG.
7, the drainage reservoir 42 is shown to also function as the
sealing device 24 in the frontal bone 18. A variety of check valve
types may be incorporated in these embodiments, such as the nipple
plug type valve shown in FIGS. 7-10, or a butterfly valve (not
shown). The reservoir 42 is shown in the figures to be formed from
an apertured upper plate 44, a closed bottom plate 46, connected
together by a side wall 48 which includes perforations such as
longitudinal slits 50 which allow fluid to drain from the reservoir
42. In FIG. 7, the reservoir 42 is shown to include a widened
sealing flange 52, to seal and anchor against the frontal sinus
bone 18. The nipple plug type valve components are best shown in
FIG. 10, to include an upper orifice plate 54 and a lower nipple
plug 56 operative to seal in the orifice plate 54. The plate 54 and
plug 56 are joined together in a normally closed position (shown in
FIG. 8), by a spring member 58, having a tension such that the
valve is fluid openable under predetermined pressures associated
with glaucoma to allow fluid to flow through the orifice plate 54
and out the perforations 50. When implanted, once the pressure
diminishes the nippled plug 56 will reseal against the orifice
plate 54.
[0035] Method of Treatment of Glaucoma--Surgical Implantation and
Testing
[0036] Surgical implantation of the shunt 10 in accordance with the
present invention is described below, following aseptic preparation
of the surgical field including the eye and skin of the patient and
positioning the patient under an operating microscope. Over the
ipsilateral frontal bone, the skin, subcutaneous tissues, and
muscle over the zygomatic process of the frontal bone are incised.
The incision should be long enough to expose the frontal bone over
the frontal sinus (typically approx 1" long and oriented
rostrocaudally. The location of the frontal sinus 16 can be
confirmed by tapping the frontal bone of the zygomatic process with
a solid object (such as a surgical instrument) to confirm a hollow
sound.
[0037] A drilling device (such as a Jacob's chuck and Steinmann's
pin--not shown), sized appropriately for the patient, is employed
to make the hole 25 in the bone 18 over the frontal sinus 16, into
the frontal sinus 16 from the exterior. The size of the hole 25
will vary with patient and species, and is matched to the size of
the sealing device 24. The sinus is visualized as a white
cavity.
[0038] Patency of the shunt 10 is confirmed by (i) cannulating the
shunt (anterior chamber end 22) with a aqueous-fluid-filled syringe
and needle (typically 27-30 ga.) assembly--not shown; (ii) flushing
the aqueous fluid (e.g. sterile balanced slat solution) through the
shunt 10 under pressure from the syringe; and (iii) visualizing
fluid passing through the valve device 26.
[0039] The frontal sinus end 20 of the shunt 10 is placed within
the trephined hole 25 of the sinus and can be held in place by
slight compression of the sealing device 24 and by the upper and
lower flanges 38, 40.
[0040] An eyelid speculum, not shown, is then placed ipsilaterally
on the eyelids to expose the conjunctival surface. A conjunctival
incision is made from the limbus (junction of cornea, schlera, and
conjuctiva) to the formix (reflexion of the conjuctiva under the
eyelid) and extended through to the epischlera.
[0041] An instrument such as pair of small forceps, not shown, is
used to bluntly dissect a tunnel from the conjunctival incision to
the frontal sinus incision (typically over the dorsal rim of the
orbit to the original surgical dissection exposing the frontal
sinus). When the tip of such instrument can be visualized it can be
used to grasp the free end (anterior chamber end 22) of the shunt.
The shunt 10 is then drawn back through the tunnel through the
conjunctival incision. The shunt 10 is layed across the surface of
the cornea and the length of the shunt is trimmed so as to adjust
its length such that is rests approximately {fraction (1/4)} of the
vertical length of the anterior chamber 14. The anterior chamber
end 22 of the shunt is trimmed obliquely at 45 to 60 degrees with
the bevel opening anteriorly.
[0042] A cutting device (e.g., 20 gauge disposable stilleto blade,
not shown) is used to enter the anterior chamber 14 at the limbus.
The angle at which the blade enters the anterior chamber should be
approximately 20.degree. (the shunt 10 should enter the anterior
chamber 14 at 10-25.degree. anterior to the limbal plane to ensure
that the shunt is positioned equal distance between the iris and
the cornea to avoid contact between the shunt and the iris, crystal
lens, or corneal endothelium).
[0043] Small forceps (e.g. tying forceps) are used to grasp the
anterior chamber end 22 of the shunt near the bevelled end, and the
shunt 10 is inserted into the anterior chamber 14. The shunt 10 is
anchored to the sclera with, for example, nonabsorbable
(monofilament) more than one (usually to or maximally (practically)
three) sutures in a simple interrupted pattern.
[0044] The Tenon's capsule and conjunctiva are closed with, for
example, simple interrupted sutures of small (7-0 to 10-0)
monofilament absorbable sutures. The frontal sinus end 20 of the
shunt is withdrawn from the frontal sinus 16 and monitored for flow
of aqueous humor through the valve device 26. When fluid flow
through the valve device 26 is confirmed, such flow is adjusted at
the valve device 26. In the case of a slit valve, the flow is
adjusted with at least one ligature device 30 around or adjacent
the slit 28 to maintain a desired intraocular pressure, which can
be measured at the corneal surface with an applanation tonometer in
the O.R. (normal for dog approximately 18 mm Hg). The valve device
26 is adjusted to open above this predetermined and known fluid
pressure associated with glaucoma. The predetermined fluid pressure
associated with glaucoma is known for other species, and the valve
device can be adjusted accordingly for other species.
[0045] The frontal sinus end 20 of the shunt 10 is then replaced
into the frontal sinus 16. Subcutaneous tissues are closed with,
for example, small (3-0 to 6-0) monofilament absorbable sutures in
a simple continuous pattern. The skin is subsequently closed with,
for example, small (3-0 to 5-0) monofilament nonabsorbable suture
in a simple interrupted pattern.
[0046] It is common with all intraocular shunts to become fibrin
coated or occluded with fibrin shortly after surgery (within the
first week post-surgery). The shunt 10 of this invention can be
flushed through the valve device 26 by incising the skin, removing
the frontal sinus end 20, and back flushing an antifibrinolytic
compound (e.g. tissue plasminogen activator (TPA)) retrograde
through the shunt. Subsequent flushing of the shunt 10 with TPA or
saline in the event of occlusion of the shunt is accomplished by
exposing the frontal sinus end 20 of the shunt 10, removing it from
the sinus 16, and flushing the shunt retrograde. When flow is
observed and the desired intraocular pressure is attained by
adjusting the valve device 26, e.g. adjusting the ligature devices
30, the frontal sinus end 20 of the shunt is then replaced, and the
surgical site closed as described above.
[0047] In the event that the intraocular pressure is observed to be
routinely less than the desired intraocular pressure, the frontal
sinus end 20 of the shunt 10 can be exposed and ligatures placed at
various intervals along the slit 28 to attain the desired
intraocular pressure.
EXAMPLE
[0048] A shunt of the present invention was designed for and
successfully implanted into four dogs having glaucoma. The details
of the implanted shunt were as follows:
[0049] Tube and Slit Valve
[0050] Inner Diameter 0.02" (0.5 mm)
[0051] Outer diameter 0.037" (0.94 mm)
[0052] Length of Tube (rough cut to be 100 mm) then tailored to
each eye in the operating room so that it extended approximately
{fraction (1/3)} away across the anterior chamber of the eye.
[0053] Slit--1 mm length
[0054] # Ligatures--4--to maintain predetermined fluid pressure,
adjusted in the operating room
[0055] Hole in the Frontal sinus bone (diameter)--(2 mm)
[0056] Plug (Sealing Device)
[0057] Central Portion (that traversed the width of the bone)--(1.5
mm)
[0058] Lower flange--2.5 mm
[0059] Upper Flange--5 mm
[0060] Length of Plug (Central Portion--traversing the bone)--3
mm
[0061] These patients did not experience frontal sinus,
subcutaneous, conjunctival or intraocular infections; fibrosis,
haemorrhage, or other untoward complications. Each of the four
patients was reoperated on within days of the first surgery to
establish and verify shunt patency and operation and to demonstrate
readjustment of the valves and retrograde flushing. Each patient
was and is continually to be monitored for visual function and
untoward side effects. All anti-glaucoma medications have been
discontinued. Regular re-examination with tonometry, visual
function testing, biomicroscopy and indirect ophthamoscopy has
demonstrated maintenance of vision and desired intraocular
pressures for period of up to 2 years post initial surgery.
[0062] Advantages
[0063] Generally, eyes inflicted with glaucoma build up protein in
the aqueous humor. Prior art implanted drainage devices often
become blocked with the protein, inhibiting fluid drainage from the
eye. To correct this problem with prior art glaucoma treatment
devices, an additional invasive surgery is needed to clean, remove,
or replace the implant. The method and shunt of the present
invention allows the correction to be made by a simple skin
incision above the frontal sinus. The sealing device 24 and
anterior chamber end 22 of the tube 12 are removed from the frontal
sinus 16, flushed with sterile fluid, and reinserted. Further
cleanings are not normally required. The fibrous tissue that
collects around the shunt once implanted forms a tunnel from the
sinus incision to the anterior chamber 14. If the shunt 10 needs to
be replaced, the original can be removed through the sinus incision
and a new device inserted through the tunnel created by the fibrous
tissue. An extensive surgery is not required.
[0064] All publications mentioned in this specification are
indicative of the level of skill in the art to which this invention
pertains. To the extent they are consistent herewith, all
publications mentioned in this specification are herein
incorporated by reference to the same extent as if each individual
publication was specifically and individually indicated to be
incorporated by reference. No admission is made that any cited
reference constitutes prior art.
[0065] Although the foregoing invention has been described in some
detail by way of illustration and example, for purposes of clarity
and understanding it will be understood that certain changes and
modifications may be made without departing from the scope or
spirit of the invention as defined by the following claims.
REFERENCES
[0066] Cullen, C. L., Allen, A. L., & Grahn, B. H. 1998,
"Anterior chamber to frontal sinus shunt for the diversion of
aqueous humor: a pilot study in four normal dogs", Veterinary
Ophthalmology, vol. 1, pp. 31-9.
[0067] Gal, M. A Novel Glaucoma Drainage Valve, 1999 [WWW
document]. Proquest Digital Dissertations (visited 2002, Feb. 28).
URL http://wwwlib.umi.com/dissertations/gateway
[0068] Glaucoma Research Foundation (visited 2002, Mar. 11). Learn
About Glaucoma [WWW document]. URL http://www.glaucoma.org/
[0069] Moffett, D., Moffett, S., & Schauf, C. 1993, Human
Physiology Foundations & Frontiers, 2.sup.nd edn, Mosby, St.
Louis.
[0070] U.S. Pat. Nos. 6,142,969 and 6,007,510 to Nigam. (Anamed,
Inc.).
[0071] U.S. Pat. Nos. 5,454,796 and Des. 356,867 to Krupin (Hood
Laboratories).
* * * * *
References