U.S. patent application number 11/420946 was filed with the patent office on 2006-09-28 for ophthalmologic applanation prism replacement system for eye examining instrument.
This patent application is currently assigned to AUTOTONOMETER CORPORATION. Invention is credited to FrancisY JR. Falck, RobertW Falck.
Application Number | 20060217611 11/420946 |
Document ID | / |
Family ID | 39225932 |
Filed Date | 2006-09-28 |
United States Patent
Application |
20060217611 |
Kind Code |
A1 |
Falck; FrancisY JR. ; et
al. |
September 28, 2006 |
Ophthalmologic Applanation Prism Replacement System for Eye
Examining Instrument
Abstract
A replaceable prism for an eye examining instrument is made to
be discarded after each use. A bendable tab molded on the prism is
deformed by a strain gauge as the prism is inserted into a prism
holder, and a signal from the strain gauge is used to verify that a
previously unused prism has been inserted into the holder. A
microprocessor is programmed to recognize the signal produced by
initial deformation of the prism tab so as to proceed with an eye
examination only after receiving the strain gauge signal verifying
that a previously unused prism has been inserted.
Inventors: |
Falck; FrancisY JR.;
(Stonington, CT) ; Falck; RobertW; (Pawcatuck,
CT) |
Correspondence
Address: |
BROWN & MICHAELS, PC;400 M & T BANK BUILDING
118 NORTH TIOGA ST
ITHACA
NY
14850
US
|
Assignee: |
AUTOTONOMETER CORPORATION
35 Washington Street Suite 2
Mystic
CT
|
Family ID: |
39225932 |
Appl. No.: |
11/420946 |
Filed: |
May 30, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10453253 |
Jun 3, 2003 |
|
|
|
11420946 |
May 30, 2006 |
|
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Current U.S.
Class: |
600/406 |
Current CPC
Class: |
A61B 3/16 20130101 |
Class at
Publication: |
600/406 |
International
Class: |
A61B 3/16 20060101
A61B003/16 |
Claims
1. A system ensuring replacement of a molded resin prism used in an
eye examining instrument having a microprocessor and a holder for
receiving the prism in an operating position, the system
comprising: the prism being molded to have an element that is
deformable in a direction of insertion of the prism into the
holder; a strain gauge arranged in the holder to engage the element
as the prism is being inserted into the holder and before the prism
reaches the operating position; the strain gauge being arranged to
deform the element from its initial position to a deformed position
as the prism is moved fully into the holder to the operating
position; the strain gauge being arranged to produce a strain
signal delivered to the microprocessor representing the strain
involved in deforming the element from its initial position to its
deformed position; the element being configured so that a first
deformation of the element from its initial position to its
deformed position requires more stress than any subsequent
deformation of the element from its initial position to its
deformed position; the microprocessor being programmed to
distinguish between a strain signal from the strain gauge
representing the first deformation of the element and a strain
signal from the strain gauge representing the subsequent
deformation of the element; and the microprocessor being programmed
to proceed with an eye examination only if a prism inserted into
the holder causes the strain gauge to produce a strain signal
representing the first deformation of the element.
2. The system of claim 1 wherein the prism has a location
projection that detents in the holder when the prism is in the
operating position.
3. The system of claim 1 wherein the element is a bendable tab and
the deformation is a bending of the tab.
4. The system of claim 1 wherein the prism has a grippable tab by
which the prism is inserted into the holder.
5. An eye examining instrument having a microprocessor and a prism
holder combined with a molded resin prism insertable into the
holder in a way that requires prism replacement before proceeding
with an eye examination, the combination comprising: the prism
being molded with an element extending transversely of a direction
of insertion of the prism into the holder; the element being
deformable from an initial position to a deformed position as the
prism is inserted into the holder and into an operating position
within the holder; the element being configured so that a first
deformation of the element requires more stress than any subsequent
deformation of the element; the holder including a strain gauge
positioned to engage and deform the element as the element is
inserted into the holder; the strain gauge being arranged to
produce a signal representing the strain encountered in deforming
the element as the prism is inserted into the holder; the
microprocessor being programmed to recognize the strain gauge
signal representing the first deformation of the element; the
microprocessor being programmed to proceed with an eye examination
whenever insertion of a prism into the holder causes the strain
gauge to produce the signal representing the first deformation of
the element; and the microprocessor being programmed not to proceed
with an eye examination whenever insertion of a prism into the
holder causes the strain gauge to produce a signal distinguishably
smaller than the signal representing the first deformation of the
element.
6. The combination of claim 5 wherein the prism has a locator
projection that seats in the holder in a detented position when the
prism is in its operating position.
7. The combination of claim 5 wherein the prism has a gripping tab
by which the prism is inserted into the holder.
8. The combination of claim 5 wherein the element is a hinged
tab.
9. A method of ensuring that a molded resin prism is replaced in an
eye examining instrument before each eye examination, the method
comprising: forming prism replacements that each have a tab that is
initially deformable in response to a predetermined stress;
inserting one of the prism replacements into a prism holder of the
instrument so that the deformable tab engages a strain gauge in the
holder and becomes deformed by the strain gauge as the prism is
moved into an operating position within the instrument; using the
strain gauge to produce a signal representing the strain
encountered in initially deforming the tab as the prism is inserted
into the holder; transmitting the strain gauge signal to a
microprocessor in the instrument and programming the microprocessor
to recognize the strain gauge signal representing the initial
deformation of the tab; and programming the microprocessor to
proceed with an eye examination only upon receiving the strain
gauge signal representing the initial deformation of the tab.
10. The method of claim 9 including programming the microprocessor
not to proceed with an eye examination and to indicate to the
instrument user upon receiving a strain gauge signal
distinguishably smaller than the strain gauge signal representing
initial deformation of the tab.
11. A method of insuring that an eye contacting prism is replaced
before each examination of a pair of eyes, the method comprising:
molding the prism of resin with a deformable element that is
deformable to a predetermined extent without breaking away from the
prism; configuring the deformable element to have an initial
resistance to an initial deformation to the predetermined extent
and a reduced resistance to any subsequent deformation to the
predetermined extent; arranging a strain gauge within an eye
examining instrument to measure deformation resistance of the
deformable element as the prism is inserted in the instrument;
arranging the strain gauge to produce a strain signal delivered to
a microprocessor in the instrument as representative of the
deformation resistance of the deformable element; and programming
the microprocessor to proceed with the examination of the pair of
eyes only when the strain signal coincides with the strain
representing the initial resistance.
12. The method of claim 11 including programming the microprocessor
not to proceed with the examination of the pair of eyes and to
indicate to the instrument user when the strain signal
distinguishably differs from the strain representing the initial
resistance.
13. An eye examining instrument and an eye contacting prism
combined to ensure replacement of the prism before proceeding with
examination of a pair of eyes, the combination comprising: the
prism having a deformable element configured to have a larger
resistance to an initial deformation and a smaller resistance to a
subsequent deformation; the instrument having a strain gauge
arranged to cause deformation of the deformable element as the
prism is inserted into the instrument; a microprocessor in the
instrument receiving a deformation signal from the strain gauge and
being programmed to recognize an initial deformation signal
corresponding to the strain encountered during the initial
deformation of the deformable element; and the microprocessor being
programmed to proceed with the examination of the pair of eyes only
upon receiving the initial deformation signal.
14. The combination of claim 13 wherein the deformable element is a
bendable tab oriented transversely to a direction of insertion of
the prism into the instrument.
15. The combination of claim 13 wherein the deformable element is
configured not to break away from the prism.
16. The combination of claim 13 wherein the prism includes a
location projection that snap fits into a seated position when the
prism is in an operating position within the instrument.
17. A disposable molded resin prism useable in an eye examining
instrument, the prism comprising: a bendable tab formed of the
molded resin of the prism to extend from a body of the prism; the
tab being configured to be bent from an initial position to a bent
position as the prism is inserted into the instrument; the tab
being formed to survive bending without breaking off from the prism
body during insertion of the prism into the instrument and removal
of the prism from the instrument for disposal; and the tab being
formed to have a resistance to an initial bending to the bent
position that is larger than any resistance of the tab to a
subsequent bending to the bent position.
18. The prism of claim 17 wherein the tab is formed with a thin
hinge line allowing the tab to bend.
19. The prism of claim 17 wherein the tab extends from a
non-optical surface of the prism body.
20. The prism of claim 17 wherein the tab extends transversely of
the direction of insertion of the prism into the instrument.
Description
RELATED APPLICATION
[0001] This is a continuation-in-part patent application of
co-pending application Ser. No. 10/453,253, filed 3 Jun. 2003,
entitled "Ophthalmologic Applanation Prism Replacement System". The
aforementioned application is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] Eye examining instruments using prisms.
BACKGROUND
[0003] It is desirable to discard and replace an instrument prism
after it has contacted and become wetted with tears of a pair of
eyes being examined. Discarding used prisms can prevent transfer of
bacteria, viruses or prions from one patient to another. For this
purpose, our previous Pat. Nos. 5,070,875, 6,179,779, and 6,471,647
and our pending application Ser. No. 09/811,709 and 10/178,987 have
suggested a few ways of making tonometer prisms readily
replaceable. The desirability of replacing applanation prisms is
not limited to tonometers, though. As revealed in our application
Ser. No. 10/178,987, eye contacting prisms are also useable in
ophthalmologic instruments examining eyes for purposes other than
tonometry.
SUMMARY
[0004] The invention of this application involves an improved form
of replaceable prism and a new interaction or interrelationship
between a prism and a tonometer or other eye examining instrument
arranged to ensure that the prism is replaced after each
examination of a pair of eyes. The prism and its interaction with
the instrument that holds it are aimed at low cost and simplicity
so that prism replacement will not be unduly expensive in material,
time or labor. Making prism disposal and replacement convenient and
efficient helps ensure that prisms will actually be replaced rather
than reused with possible risk to patients.
[0005] To accomplish this the invention involves a configuration of
a disposable prism that is molded of resin to operate within an
instrument having a microprocessor and a prism holder into which
the prism is inserted in a way that requires prism replacement
before proceeding with an eye examination. The prism has a molded
element formed to extend transversely of a direction of insertion
of the prism into the holder, and the element is deformable from an
initial position to a deformed position as the prism reaches an
operating position within the holder. The element is also
configured so that its first deformation requires a distinct stress
not required for any subsequent deformation. Deformation of the
element is accomplished by a strain gauge positioned in the holder
to engage the element and produce a signal representing the strain
encountered in deforming the element as the prism is inserted into
the holder. The microprocessor is programmed to recognize the
strain gauge signal representing the first deformation of the
element and to proceed with an eye examination only when insertion
of the prism into the holder causes the strain gauge to produce the
signal representing the first deformation of the element.
DRAWINGS
[0006] FIG. 1 is a partially schematic elevational view of a
preferred embodiment of prism and prism holder combined with a
schematically represented instrument.
[0007] FIG. 2 is a partially schematic plan view of the prism and
holder shown in FIG. 1.
[0008] FIG. 3 is a partially schematic plan view of the prism
holder as shown in FIG. 2, with the prism removed.
[0009] FIG. 4 is a plan view of a preferred embodiment of a prism
combinable with a holder shown in FIGS. 2 and 3 and useable with
the instrument of FIG. 1.
[0010] FIG. 5 is a front elevational view of the prism of FIG.
4.
[0011] FIG. 6 is a rear elevational view of the prism of FIG.
5.
[0012] FIG. 7 is a front elevational view of the prism and holder
of FIGS. 1 and 2.
[0013] FIG. 8 is a partially schematic and fragmentary cross
sectional view of the prism and holder of FIG. 7, showing the prism
being inserted part way into the holder.
[0014] FIG. 9 is a partially schematic and fragmentary cross
sectional view of the prism and holder of FIG. 7, taken along the
line 9-9 thereof, and showing the prism fully inserted into the
holder.
[0015] FIG. 10 is an enlarged, fragmentary cross sectional view of
a preferred embodiment of a deformable element for the prism of
FIGS. 4-6.
DETAILED DESCRIPTION
[0016] An eye examining instrument 10, as shown schematically in
FIG. 1 includes an applanation prism 20, a prism holder 50 and a
microprocessor 60. Instrument 10 can be an applanation tonometer
such as disclosed in our previous Pat. Nos. 5,070,875 and
6,179,779. Applanation prisms and prism holders are also useful in
other eye examining instruments for measuring eye properties other
than intra ocular pressure. As explained in our application Ser.
No. 10/178,987, such instruments, can use applanation prisms for
measuring ocular blood flow, tonography, and different aspects of
intra ocular pressure measurements such as systolic pressure,
diastolic pressure, and average or mean intra ocular pressure. For
purposes of this invention, what is important is not what
measurement instrument 10 is being used for, but the configurations
and interactions between prism 20, and holder 50. Also unimportant
is the optical or metrologic properties of prism 20, which can be
any energy transmitting device having a surface that contacts the
eye.
[0017] A body 11 of instrument 10 is schematically illustrated in
FIG. 1, because it not only can have many different shapes but also
preferably uses different shapes for different purposes. For
example, body 11 can have one shape when mounted on and powered by
a slit lamp microscope, and can have a different shape configured
as a battery powered, hand held portable instrument. Shapes for
body 11 made suitable for either of these purposes can also vary
widely for other reasons involving materials, costs, and
appearance.
[0018] Prism 20 is preferably molded of resin material to be
inexpensive and thus affordably replaceable. Prism 20 is also
configured to be easily inserted into and removed from holder 50 so
that discarding prism 20 after each use is convenient as well as
affordable. Finally, as explained below, prism 20 and holder 50 are
configured so that instrument 10 can reliably determine that a
previously unused prism 20 is positioned in holder 50 before
proceeding with an eye examination. This ensures that prism 20 is
actually replaced for each successive patient.
[0019] For ease of insertion and removal, prism 20 preferably has
an integrally molded gripping tab 21. An eye contacting surface 19
of prism 20 should not be touched or handled as a fresh prism is
inserted into holder 50, and we prefer that prism 20 have a
gripping tab 21 arranged to be handled while inserting and removing
prism 20. The position and orientation of gripping tab 21 depends
partly on the direction and orientation of the prism insertion and
removal motions. Since we prefer lowering prism 20 downward into
holder 50 from above, we also prefer that gripping tab 21 be
conveniently arranged to extend upward from prism 20. In such a
position, tab 21 is disposed to be gripped by a thumb and finger
for conveniently pushing prism 20 downward into holder 50, and for
lifting prism 20 upward out of holder 50 after it has been used.
Gripping tab 21 can also be configured in different ways and
arranged in different positions, depending partly upon the most
convenient way chosen for inserting and removing prism 20.
[0020] The proper location of prism 20 when it is inserted into
holder 50 is also important. An improperly seated prism 20 could
fail to produce operable results. To prevent this we prefer a prism
locating and detenting system that not only ensures proper seating
of an inserted prism, but also lets a person inserting the prism
know when proper seating has occurred. For these purposes,
preferred prism 20 has a location projection 25 that extends
downwardly from prism 20 in an opposite direction from gripping tab
21 to locate the prism properly in holder 50. A different position
or orientation for projection 25 is also possible, especially for a
prism that is inserted into holder 50 in a different way.
[0021] Projection 25 also preferably detents or snap locks into
place when prism 20 is properly positioned. FIGS. 8 and 9 best show
this action of location tab 25. Prism 20 is shown partially
inserted into holder 50 in FIG. 8, where location projection 25 is
sliding over detent 26. To ease this motion, detent 26 has a cammed
entry surface 27. After prism 20 is fully seated in holder 50, as
shown in FIG. 9, an aperture or opening 30 in locator projection 25
snaps over and locks against detent 26 to hold prism 20 firmly in
an operating position.
[0022] Removing prism 20 after it has been used in examining a pair
of eyes requires pulling back on the lower tip 29 of location tab
25 to release its locking engagement with detent 26. Prism 20 can
then be lifted out of holder 50 by gripping and pulling upward on
tab 21. For prism release purposes, the lower end 29 of location
tab 25 preferably extends below the bottom of holder 30, where it
is accessible to finger pressure releasing projection 25 from
detent 26.
[0023] A slot 28 in holder 50 containing detent 26 is angled
slightly relative to the orientation of tab 25, which urges
location projection 25 rearwardly as prism 20 is pushed downwardly
into holder 50. This draws prism 20 rearwardly as it is inserted
into holder 50 and ensures that prism port surfaces 22 and 23 are
drawn snugly and respectively against emitter 52 and detector 53,
which are arranged in holder 50 as shown in FIG. 2. Light from
emitter 52 can then reliably enter prism port 22 to be incident on
applanation surface 19 of prism 20 and be partially reflected to
prism port 23 and detector 53. Prism ports 22 and 23 are preferably
identical so that emitter 52 and detector 53 can be arranged on
either side of prism 20. The amount of light reaching detector 53
depends on the size of an area of cornea applanated by prism
surface 19. The operation and affect of such a light path is
explained in our previous Pat. Nos. 5,070,875 and 6,179,779 and in
our application Ser. No. 10/178,987. Eye contacting prisms used for
purposes other than tonometry can have different ports and
different configurations, depending upon the energy being
transmitted and the measurement or observation being made.
[0024] There are many different ways that a prism 20 can be
detented or snap locked into a holder 50, other than the particular
detent illustrated. What is preferred for any such arrangement is
that a detent be positive and noticeable to a person inserting
prism 20, to indicate that the prism is fully inserted into holder
50. It is also preferred that the detenting of the prism into the
holder be quick and efficient, both for insertion and removal. The
detenting system also preferably urges prism 20 rearwardly to
insure that prism port surfaces 22 and 23 engage emitter 52 and
detector 53 in prism holder 50 for reliable optical operation. The
illustrated interlock between tab 25 and detent 26 accomplishes
these objectives, but is clearly not the only plausible solution.
Different paths of movement for insertion and removal of prism 20
can lead to different detent systems that accomplish similar
objectives.
[0025] The interaction between prism 20 and holder 50 of instrument
10 is also preferably arranged to require that prism 20 be replaced
after each examination of a pair of eyes. The interaction proposed
by this invention, is a new way of accomplishing that. The goal is
to preclude instrument 10 from examining a new pair of eyes until a
new prism 20 is inserted into holder 50.
[0026] The preferred prism replacement requirement is met by a
deformable element 40 integrally formed on prism 20 to extend
transversely of the path of movement followed by prism 20 as it is
inserted into holder 50. Interacting with deformable tab 40 is a
strain gauge 45 mounted in holder 50 and communicating with
microprocessor 60 in instrument 10. As prism 20 is inserted into
holder 50, deformable tab 40 encounters strain gauge 45, as shown
in FIG. 8. As prism 20 proceeds from a partially inserted position
shown in FIG. 8 to a fully inserted position shown in FIG. 9,
deformable tab 40 is bent from an initial position shown in FIG. 8
to a deformed position shown in FIG. 9. The bending of deformable
element 40 requires stress supplied by the person pushing downward
on grippable tab 21 in the course of pushing prism 20 down into
holder 50. Such a stress force is preferably minor and easily
achieved by the person inserting prism 20.
[0027] Strain gauge 45, which engages and requires deformation of
element 40 as prism 20 is inserted into holder 50 produces a signal
representing the strain encountered in bending tab 40. This signal
is delivered to microprocessor 60, which is programmed to recognize
a strain signal produced by an initial bending of deformable
element 40. Any subsequent bending of element 40 requires a
different and preferably reduced strain on gauge 45, which then
produces a distinguishably different signal to microprocessor 60.
By this arrangement, instrument 10 is able to recognize reliably
the insertion of a previously unused prism 20 into holder 50,
because of the distinct signal produced by strain gauge 45
encountering a never previously deformed tab 40. Microprocessor 60
is then programmed to proceed with an eye examination only after
receiving the appropriate signal from strain gauge 45 indicating
that an unused prism 20 has been inserted into holder 50.
[0028] A preferred way of configuring deformable element 40 so that
its initial deformation produces a distinct signal from strain
gauge 45 is to mold element 40 with a thin hinge connection 41 to
prism 20, as best shown in the enlarged fragmentary view of FIG.
10. Initial bending of element 40 then requires more stress than
any subsequent bending of element 40, and this in turn exerts a
distinctive strain on gauge 45 during the initial bending of tab
40. Experiments have shown that tape, glue, and other
reinforcements of an already-bent tab 40 do not succeed in
restoring tab 40 to its initial condition and its initial ability
to produce the initial strain signal from gauge 45. From this it
appears that the deformable element and strain gauge combination
for a prism replacement requirement cannot be easily defeated.
[0029] An advantage of deformable element 40 and strain gauge 45 is
that element 40 is not broken away from prism 20 as it is bent
during prism insertion. Having a prism element break off and leave
a separate piece loose within holder 50 is undesirable, as likely
to interfere with operations of holder 50.
[0030] Another advantage of deformable element 40 is that it is
preferably molded integrally with prism 20. Experiments have shown
that polymers having the desired optical properties for prism 20
can also provide deformable element 40 so that it co-operates
successfully with strain gauge 45, as explained above. This helps
make prism 20 inexpensive, which in turn is desirable to make its
discard and replacement affordable.
[0031] Deformable elements usable in co-operation with a strain
gauge to determine that a replaced prism has not been previously
used can also be arranged in other ways. One configuration we
prefer is that the deformable element extends in a direction
transverse to the direction of insertion of prism 20 into holder
50. Changing the direction of the path followed by prism 20 as it
is inserted into holder 50 then changes the preferred direction of
orientation of any deformable element. This in turn would change
the position of strain gauge 45. It is also not essential that
deformable element 40 be a bendable tab, as illustrated. A beam of
prism resin material could be integrally connected at each of its
ends to prism 20 and be deformable in a central region encountered
by a strain gauge. Other variations on deformable elements are
possible, such as diaphragms or projections that do not bend as far
as illustrated. In addition, there are many ways of ensuring that
an initial deformation of a molded element exerts a strain on a
gauge distinctively different from any subsequent deformation of
the element. For example, a bendable element could have a thin
molded prism connection that breaks in one region to allow
deformation of another connection that does not break. We prefer
that any deformable element be integrally molded with prism 20,
rather than requiring a separate construction attached to prism 20.
Although separately fabricated elements could be made to co-operate
successfully with a strain gauge, separate constructions generally
cost more and would tend to increase the cost of prism 20.
[0032] Eye contacting prisms that are preferably replaced after
each examination of a pair of eyes can be used in other eye
examining instruments such as pachymeters, which measures corneal
thickness. Pachymeters can direct energy such as ultrasonic or
light waves through a prism or window contacting an eye while its
corneal thickness is measured. Other eye examining instruments can
be devoted to measurements of ocular pulse pressure, ocular blood
flow, and topography, such as explained in our pending application
Ser. No. 10/178,987, although these functions are preferably
combined with a tonometer that measures intraocular pressure.
[0033] Prism 20 is also improved in several other respects. It
preferably has a hollow rear region 18, as best shown in FIGS. 8
and 9, to reduce the amount of material required and simplify the
molding requirements for prism 20. Prism 20 is also preferably made
so that an operator can see or sight through prism 20 to guide it
as it approaches a cornea of an eye. For such sighting purposes,
rear face 16 of prism 20 is formed with a reticle 17 identifying a
sighting center or prism axis extending through prism 20. The
applanation face 19 of prism 20, which is generally flat, is then
provided with a small central indent 15 on the optical or sighting
axis through prism 20. Indent 15 does not internally reflect light
to detector 53 and thus produces a small dark spot on the front
face 19 of prism 20. A viewer sighting through prism 20 can then
center the dark spot caused by indent 15 within reticle 17 to
verify proper alignment of prism 20 as it approaches the optical
center of a cornea of an eye. Indent 15 and reticle 17 are each
formed integrally with prism 20 as it is molded so that neither
requires any add on parts. From the patient's point of view, indent
15 on surface 19 appears as a small bright spot. This helps the
patient fixate on the center of surface 19 as the prism approaches
the eye. The prism's sight-through feature for the instrument
operator and bright spot fixation feature for the patient,
cooperate to help insure accurate coaxial alignment of the eye and
the prism.
* * * * *