U.S. patent application number 10/680031 was filed with the patent office on 2004-12-09 for corneal vacuum centering guide and dissector.
Invention is credited to Davenport, James, Loomas, Bryan, Mathis, Mark.
Application Number | 20040249403 10/680031 |
Document ID | / |
Family ID | 25350387 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040249403 |
Kind Code |
A1 |
Loomas, Bryan ; et
al. |
December 9, 2004 |
Corneal vacuum centering guide and dissector
Abstract
This invention is a surgical device for producing a generally
circular, interlamellar pathway within the corneal stroma of the
eye. The device is made up of three major components: a vacuum
centering guide having an inner bore which fits at one end against
the front of the eye, a barrel which fits within the inner bore of
the centering guide and to which is attached the third major
component, a generally circular dissecting ring. The dissecting
ring is shaped in such way that when an eye surgeon twists the
barrel to which the ring is attached, the ring moves through the
interlamellar space in the stroma producing the desired channel or
pathway. The centering guide may optionally include a ring having
one or more pins which firmly engage the cornea's epiphilium. The
constituent parts of the surgical device, particularly the
dissecting ring, also form a part of this invention. A split ring,
or intracorneal ring ("ICR"), is inserted into the intrastromal
passageway produced by the inventive device. The ICR changes the
shape of the cornea and, in doing so, provides a chosen measure of
visual correction.
Inventors: |
Loomas, Bryan; (Santa Clara,
CA) ; Davenport, James; (Fallbrook, CA) ;
Mathis, Mark; (Fremont, CA) |
Correspondence
Address: |
BINGHAM, MCCUTCHEN LLP
THREE EMBARCADERO, SUITE 1800
SAN FRANCISCO
CA
94111-4067
US
|
Family ID: |
25350387 |
Appl. No.: |
10/680031 |
Filed: |
October 6, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10680031 |
Oct 6, 2003 |
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08933855 |
Sep 19, 1997 |
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6632232 |
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08933855 |
Sep 19, 1997 |
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08401465 |
Mar 9, 1995 |
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08401465 |
Mar 9, 1995 |
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08214654 |
Mar 15, 1994 |
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5403335 |
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08214654 |
Mar 15, 1994 |
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07867745 |
Apr 10, 1992 |
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Current U.S.
Class: |
606/166 |
Current CPC
Class: |
A61F 2/147 20130101;
A61B 2017/306 20130101; A61B 2017/320052 20130101; A61F 9/013
20130101 |
Class at
Publication: |
606/166 |
International
Class: |
A61F 009/00 |
Claims
1. A dissector blade assembly suitable for forming a generally
circumcorneal interlamellar annular channel in the cornea of an eye
comprising: a dissector having a cross-section, which blade is in
the form of a major arc having a diameter in a plane about an axis,
said axis being perpendicular to the plane of the major arc of the
dissector, having a single dissecting end so to separate layers of
stroma within the cornea and to form an intramellular channel
within the corneal stroma of an eye and having a support end, and a
dissector support attached to the dissector support end in which
the dissector support is at an angle of up to about 80.degree. to
the plane of the dissector.
2 to 42 (Canceled).
Description
FIELD OF THE INVENTION
[0001] This invention is a surgical device for producing a
generally circular, interlamellar pathway within the corneal stroma
of the eye. The device is made up of three major components: a
vacuum centering guide having an inner bore which fits at one end
against the front of the eye, a barrel which fits within the inner
bore of the centering guide and to which is attached the third
major component, a generally circular dissecting ring. The
dissecting ring is shaped in such a way that when an eye surgeon
twists the barrel to which the ring is attached, the ring moves
through the interlamellar space in the stroma producing the desired
channel or pathway. The centering guide may optionally include a
ring having one or more pins which firmly engage the cornea's
epiphilium. The constituent parts of the surgical device,
particularly the dissecting ring, also form a part of this
invention.
[0002] A split ring, or intracorneal ring ("ICR"), is inserted into
the intrastromal passageway produced by the inventive device. The
ICR changes the shape of the cornea and, in doing so, provides a
chosen measure of visual correction.
BACKGROUND OF THE INVENTION
[0003] An oma lies in the overall shape of the eye can cause visual
disorders. Hyperopia ("farsightedness") occurs when the
front-to-back distance in the eyeball is too small. In such a case,
parallel rays originating greater than 20 feet from the eye focus
behind the retina. In contrast, when the front-to-back distance of
eyeball is too large, myopia ("nearsightedness") occurs and the
focus of parallel rays entering the eye occurs in front of the
retina. Astigmatism is a condition which occurs when the parallel
rays of light do not come to a single point within the eye, but
rather have a variable focus due to the fact that the cornea is
aspherical and refracts light in a different meridian at different
distances. Some degree of astigmatism is normal, but where it is
too high, it must often be corrected.
[0004] Hyperopia, myopia, and astigmatism are usually corrected by
glasses or contact lenses. Surgical methods for the correction of
such disorders are known. Such methods include radial keratotomy
(see, e.g., U.S. Pat. Nos. 4,815,463 and 4,688,570) and laser
corneal Ablation (see, e.g., U.S. Pat. No. 4,941,093)., Another
method for correcting those disorders is through the implantation
of polymeric rings in the eye's corneal stroma to change the
curvature of the cornea. Previous work involving the implantation
of polymethylmethacrylate (PMMA) rings, allograft corneal tissue,
and hydrogels is well documented. One of the ring devices involves
a ring design that allows a split ring to be inserted into a
channel dissected in the stromal layer of the cornea using a
minimally invasive incision through which the channel for the
implant is created and through which the implant is inserted.
[0005] U.S. Pat. No. 4,452,235, to Reynolds, describes a method and
apparatus for corneal curvature adjustment. The method involves
inserting one end of a split end adjusting ring into the cornea of
the eye and moving the ring in a circular path until its ends meet.
The ends are thereafter adjusted relative to each other until the
shape of the eye has assumed a desired curvature whereupon the ends
are fixedly attached to maintain the desired curvature of the
cornea.
[0006] Although the procedure for introducing ICRs into the
intracorneal stroma is known, our inventive insertion devices used
to implement these procedures is not shown.
[0007] Vacuum devices useful for ocular surgical procedures are,
however, common. For instance, U.S. Pat. No. 4,423,728, to
Lieberman, shows a cam-guided trephine for selectively cutting a
circular or V-shaped groove about the cornea. The device utilizes a
pair of suction rings which affix the apparatus onto the sclera of
the patient's eye. The vacuum is usually less than about 10 cm of
water thereby avoiding raising the intraocular pressure above the
physiological levels. The suction ring lies in the anatomically
constant area just outside the limbus.
[0008] Similarly, U.S. Pat. No. 4,997,437 to Grieshaber, shows a
process and apparatus for cornea grinding. The device has a base
member which is held to the conjunctiva of the eye by vacuum space
formed about the periphea of the cornea. A rotary grinder is
attached to the base member and slides onto the eye through the
interior bore of the base member. No-provision is made for
preventing rotation of the base member.
[0009] None of these disclosures shows the combination of devices
similar to those disclosed herein.
[0010] Suggestion of blunt points or dissectors for producing
channels within the interlamellar boundaries are found. See, for
instance, U.S. Pat. No. 5,090,955, to Simon and "Intrastromale
Implantation Eines Justierbaren Kunstofforings Zur Hornhau
Trefraktion Sanderung", Hartmann et al., ______ pp. 465-475. They
do not suggest the special relationship shown with the dissector
support.
[0011] An optional aspect of this invention is the use of pins
which engage the front of the eye to prevent rotation of the
inventive device during use.
[0012] U.S. Pat. No. 4,429,696, to Hanna, shows a surgical
apparatus for precisely cutting out the cornea of the eye by making
at least one circular incision. The device is held to the front of
the eye by a series of claws, which optionally may be retractable,
and suction placed on the central portion of the eye during the
cutting operation. There is no suggestion of using the claws in
cooperation with an annular vacuum ring.
[0013] Finally, the invention may optionally include a soft base
conformable to the surface of the eye.
[0014] Such devices are known. See, for example, published PCT
Application WO91/08711, to Kilmer et al., shows a device for
re-profiling a cornea. The device rests on a resilient vacuum ring
which is adapted to sit on the sclera portion of an eye which
surrounds the cornea which is to be re-profiled. The top side of
the vacuum ring has a number of positioning pins which allow it to
be connected to the remainder of the profiling apparatus.
[0015] The invention described herein is a device for producing in
the corneal stroma, the circular pathway needed for the insertion
of the ICR using a suction ring which detachably adheres to the
front of the eye.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a horizontal section of an eye.
[0017] FIG. 2 is a horizontal section of the anterior portion of an
eye.
[0018] FIG. 3 is a front perspective view of the constituent parts
of the inventive vacuum device and their relationship to the eye
during use.
[0019] FIG. 4 is a bottom view of the base of the vacuum
device.
[0020] FIG. 5 is a bottom view of the centering insert for the
inventive device.
[0021] FIG. 6 is a bottom view of the dissector and its supporting
insert barrel as used in the inventive device.
[0022] FIG. 7 is a side view of the dissector blade. FIG. 7a is a
side cross-section of the dissector blade. FIGS. 7b and 7c are top
and side views of the tip of the dissector blade.
[0023] FIG. 8 is a side cross-section view of the vacuum device in
place on the eye during the step of making the initial incision for
later installation of an ICR.
[0024] FIG. 9 is a side cross-sectional view of the vacuum device
in place during the step of dissecting a circular channel in the
corneal stroma.
[0025] FIG. 10 is a bottom view of a variation of the invention
utilizing multiple vacuum chambers.
[0026] FIG. 11 is a side cross-sectional view of the inventive
variation shown in FIG. 10.
[0027] FIG. 12 is a bottom view of a variation of the invention
utilizing a single chamber in the base.
[0028] FIG. 13 is a partial side cross-sectional view of a
variation of the invention shown in FIG. 12.
[0029] FIG. 14 is a bottom view of a variation of the invention
also utilizing multiple vacuum chambers.
[0030] FIG. 15 is a partial side cross-sectional view of the
variation shown in FIG. 14.
[0031] FIG. 16 shows a soft insert suitable for producing a vacuum
on the front of the eye.
[0032] FIGS. 17, 18 and 19 are enlarged side cross-sectional views
of peripheral or outer edge of the vacuum base where they would
meet the surface of the eye during use.
[0033] FIG. 20 shows a bottom view of a variation of the device
which incorporates radial walls within the vacuum chamber to help
prevent rotation of the vacuum base during ophthalmic
operations.
[0034] FIGS. 21, 22 and 23 show partial cross-sectional views of
three variations of the radial wall devices placed in the vacuum
chamber shown in FIG. 19.
[0035] FIG. 24 is a bottom view of a vacuum device showing, in
particular, an insert utilizing a number of pins for engaging the
anterior surface of the eye during the eye surgery.
[0036] FIG. 25 is a side view cross-section of the device of FIG.
24.
[0037] FIGS. 26, 27, 28, 29 and 30 depict the steps of using the
inventive device to prepare the eye and install the ICR in the
corneal stroma.
[0038] FIG. 31 shows the positioning of the ICR in the stroma.
DESCRIPTION OF THE INVENTION
[0039] Prior to explaining the details of the inventive devices, a
short explanation of the physiology of the eye is needed to
appreciate the functional relationship of the device to the
eye.
[0040] FIG. 1 shows a horizontal section of the eye with the globe
11 of the eye resembling a sphere with an anterior bulged spherical
portion representing the cornea 12.
[0041] The globe 11 of the eye consists of three concentric
coverings enclosing the various transparent media through which the
light must pass before reaching the sensitive retina 18. The
outermost covering is a fibrous protective portion, the posterior
five-sixths of which is white and opaque and called the sclera 13,
and sometimes referred to as the white of the eye where visible to
the front. The anterior one-sixth of this outer layer is the
transparent cornea 12.
[0042] A middle covering is mainly vascular and nutritive in
function and is comprised of the choroid 14, ciliary body 16 and
iris 17. The choroid 14 generally functions to maintain the retina
18. The ciliary body 16 is involved in suspending the lens 21 and
accommodation of the lens. The iris 17 is the most anterior portion
of the middle covering of the eye and is arranged in a frontal
plane. It is a thin circular disc corresponding to the diaphragm of
a camera, and is perforated near its center by a circular aperture
called the pupil 19. The size of the pupil varies to regulate the
amount of light which reaches the retina 18. It contracts also to
accommodation, which serves to sharpen the focus by diminishing
spherical aberration. The iris 17 divides the space between the
cornea 12 and the lens 21 into an anterior chamber 22 and posterior
chamber 23. The innermost portion of covering is the retina 18,
consisting of nerve elements which form the true receptive portion
for visual impressions.
[0043] The retina 18 is a part of the brain arising as an outgrowth
from the fore-brain, with the optic nerve 24 serving as a fiber
tract connecting the retina part of the brain with the fore-brain.
A layer of rods and cones, lying just beneath a pigmented
epiphilium on the anterior wall of the retina serve as visual cells
or photoreceptors which transform physical energy (light) into
nerve impulses.
[0044] The vitreous body 26 is a transparent gelatinous mass which
fills the posterior four-fifths of the globe 11. At its sides it
supports the ciliary body 16 and the retina 18. A frontal
saucer-shaped depression houses the lens.
[0045] The lens 21 of the eye is a transparent bi-convex body of
crystalline appearance placed between the iris 17 and vitreous body
26. Its axial diameter varies markedly with accommodation. A
ciliary zonule 27, consisting of transparent fibers passing between
the ciliary body 16 and lens 21 serves to hold the lens 21 in
position and enables the ciliary muscle to act on it.
[0046] Referring again to the cornea 12, this outermost fibrous
transparent coating resembles a watch glass. Its curvature is
somewhat greater than the rest of the globe and is ideally
spherical in nature. However, often it is more curved in one
meridian than another giving rise to astigmatism. A central third
of the cornea is called the optical zone with a slight flattening
taking place outwardly thereof as the cornea thickens towards its
periphery. Most of the refraction of the eye takes place through
the cornea.
[0047] Referring to FIG. 2, a more detailed drawing of the anterior
portion of the globe, shows the various layers of the cornea 12
comprising an epithelium 31. Epithelial cells on the surface
thereof function to maintain transparency of the cornea 12. These
epithelial cells are rich in glycogen, enzymes and acetylcholine
and their activity regulates the corneal corpuscles and controls
the transport of water and electrolytes through the lamellae of the
stroma 32 of the cornea 12.
[0048] An anterior limiting lamina 33, referred to as Bowman's
membrane or layer, is positioned between the epiphilium 31 and the
stroma 32 of the cornea. The stroma 32 is comprised of lamella
having bands of fibrils parallel to each other and crossing the
whole of the cornea. While most of the fibrous bands are parallel
to the surface, some are oblique, especially anteriorly. A
posterior limiting lamina 34 is referred to as Descemet's membrane.
It is a strong membrane sharply defined from the stroma 32 and
resistant to pathological processes of the cornea.
[0049] The endothelium 36 is the most posterior layer of the cornea
and consists of a single layer of cells. The limbus 37 is the
transition zone between the conjunctiva 38 and sclera 13 on the one
hand and the cornea 12 on the other.
[0050] FIG. 3 shows the various components used in this inventive
surgical device. The support base (50), includes an annular
circumcorneal vacuum ring (52) at the end proximal the cornea and a
cylindrical or central bore (54) extending from the end of the
support base distal the eye (56). The support base (50) typically
contains a viewing port (55) through the extension wall of the base
to allow the surgeon to make the initial incision into the eye and
to clearly view the operational steps which take place at the
corneal surface. The vacuum is brought in from vacuum source line
(58). The circumcorneal vacuum ring (52) is configured so that it
meets with and seals to the front of the eye rendering the support
base (50) relatively immobile when the support base is applied to
the front of the eye (56) and a suitable vacuum is applied to the
vacuum source line (58). The vacuum chamber forms an annular vacuum
space against the front of the eye. The support base (50) may also
have a pin (60) which serves as an antirotatory device for corneal
centering guide (62). Also shown in FIG. 3 is the incisor blade
(68) which is inserted by the surgeon through the viewing port
(55). An incision blade (68) is of a size and configuration which
allows the knife to enter the cornea at a depth and angle suitable
for later introduction of the dissector blade (66) into the
intracorneal stroma.
[0051] FIG. 4 shows a bottom view of support base (50) in which the
circumcorneal vacuum ring (52) may be clearly viewed. The
circumcorneal vacuum ring (52) is made up of an inner wall (70)
terminating on its inside by the central bore (54). The central
bore (54) is at least large enough to see the entirety of the
dissector blade (66) as is discussed below. The central bore (54)
has an axis which substantially coincides with the axis of the
dissector blade. The central bore (54) is desirably of a length
such that the ratio of the bore's length to its diameter is between
0.25:1 and 15:1; specifically between 0.4:1 and 1:1; at least about
1:1 and less than about 3:1; or at least about 3:1 up to about
15:1. Preferably, the ratio is about 2.5:1. This sizing allows easy
manipulation by the surgeon. The outer vacuum ring wall (72)
desirably forms the outside of the support base (50). Interior to
the circumcorneal vacuum ring (52) may be one or more ridges (74)
which extend down to the corneal surface when the support base is
attached to the guide. The ridges are positioned within the
circumcorneal vacuum ring (52) to prevent rotation of the support
base (50) during any surgical operation. Variations of the ridge
design will be discussed below with regard to FIGS. 20 through 23.
The opening (76) to the vacuum source line (58) is shown in FIG.
4.
[0052] FIG. 5 shows a bottom view of corneal centering and fixation
guide (62). This guide (62) fits down within the inner barrel (54)
of support base (50) and a groove (78) within the outer surface of
the guide slides over and engages pin (60). In this way, corneal
center and fixation guide (62) does not rotate with respect to
support base (50). The inside bore (80) and the reticle are used to
allow centering of the support base (50) about the cornea and to
allow making a marking cut with incision marker (63). Once the
surgeon determines that the support base (50) is properly centered
by using the corneal centering and fixation guide (62), vacuum is
applied through vacuum source line (58) and its terminal opening
(76) in the circumcorneal vacuum ring (52).
[0053] Once support base (50) is affixed to the front of the eye,
the corneal centering and fixation guide (62) is removed from the
center bore (54) of the support base (50) and the incision for
insertion of the dissector blade (66) is made. After the initial
incision is completed, the dissector barrel (64) is inserted down
into the inner bore (54) of the support base (50). The dissector
blade (66) is attached to the dissector barrel (64) by dissector
blade support arm (84). As the barrel rotates, it defines a barrel
axis. The barrel axis is coincident to the blade axis discussed
below.
[0054] FIG. 7 shows the desired features of the dissector blade
(66) in greater detail. The blade, in cross-section, is desirably
rectangular in cross-section. This permits a large amount of
material to be incorporated in the blade and yet form a
substantially rectangular path in the interlamellar spaces of the
corneal stroma. The blade (66) as was shown above, is in the shape
of a major arc of up to 3500 having as its center the axis (65) as
shown in FIG. 7. The blade's major arc is in a plane perpendicular
to that axis (65). The blade may be tapered on its smaller edge as
is shown in FIG. 7a and indeed may be of any convenient shape
although we have found the two noted cross-sectional shapes (i.e.,
rectangular or hexagonal in which two opposite sides are longer
than the remaining four) to be preferred. FIG. 7a shows the cone
angle (67) of the dissector blade as is discussed below and the
diameter (69) of the dissector blade (66). This diameter is
preferably viewable through the upper end of the dissector barrel
(64).
[0055] The blade is formed so that the dissector blade support arm
(84) is at an angle .alpha. of up to about 90.degree.. The angle of
the blade support arm (84) to the plane of the blade (66) may be a
value of 0.degree. to 90.degree.. It is preferably between
0.degree. and 800, more preferably the angle is
10.degree.-50.degree. and most preferably about 34.degree. (50) to
the plane of dissector blade (66). This angle results in the
dissector blade support arm (84) being generally perpendicular to
the cornea when it is inserted into the incision provided for
introduction of the dissector blade (66) into the corneal stroma.
This angle, although not absolutely critical, is desirable and has
been found to prevent tearing of the epiphilium during the corneal
operation. The length of blade angle support arm (84) is sufficient
that the entire dissector blade is visible through the top of the
dissector barrel during use--see FIG. 6. As was noted with regard
to FIG. 3, the outer diameter of the dissector barrel (64) is the
same as the bore (54) of the base (50). The overall relationship of
the sizes of the diameter of the arc (69) of the blade to the
length of the dissector barrel is desirably chosen so that the
ratio of that length to the arc diameter is between 0.25:1 and
15:1; specifically between 0.4:1 and 1:1, at least about 1:1 and
less than about 3:1; and at least about 3:1 but less than 15:1.
Again these ratios allow ease of manipulation by the surgeon.
[0056] The dissector blade (66) has two other physical parameters
which we believe to be important to the effective operation of the
support base (50) in providing an interlamellar channel in the
corneal stroma. Upon rotation of the dissector barrel (64), the
dissector blade (66) must move in a path which is substantially
planar. That is to say the path of the dissector blade (66) as it
moves in the corneal intrastromal lamellar space described above,
must not vary either up or down during the dissector barrel (64)
rotation. The distance "a" shown in FIG. 7 is a constant. The blade
can be considered to be in a plane which is perpendicular to the
axis (65) which forms the center of ring (66).
[0057] Similarly, the cone angle .beta. (67) is preferably
112.degree. (.+-.30.degree.). Again, this permits the dissector
blade (66) to produce a channel which is parallel to the lamella
found in the corneal stroma. The cone angle .beta. may, of course,
vary a few degrees dependent on such variables as the geometry of
the ICR installed, the size of the eye, and the amount of
correction required.
[0058] FIGS. 7b and 7c show one desired tip configuration of the
dissector blade (66). We have found that a comparatively blunt but
rounded device will provide an intrastromal channel fairly
precisely in a constant depth within the lamella. Sharper blades
have a tendency to cut through the lamella and produce a less
desirable intrastromal channel.
[0059] FIG. 8 shows in a cross-section the step of creating the
incision in the front of the eye using knife (68). The support base
(50) secured by circumcorneal vacuum ring (52) is in place as is
the corneal centering and fixation guide (62). The knife (68) has
been brought down through the corneal centering and fixation guide
(62) into the epiphilium and the stroma of the eye (56).
[0060] Once the steps of centering and initial incision are
complete, the corneal centering and fixation guide (62) and knife
(68) are removed and the step shown in FIG. 9 is carried out.
[0061] In FIG. 9, again the support base (50) is in place on the
front of the eye (56) secured by the vacuum in circumcorneal vacuum
ring (52). The dissector barrel (64) having dissector blade (66) on
its lower end is introduced into the inner bore of the support base
(50). The leading edge of the dissector blade is introduced into
the incision made during the step shown in FIG. 8 and the dissector
barrel is rotated as shown. The dissector barrel is rotated far
enough to make a full circular channel or until the dissector blade
support arm (84) reaches the insertion made into the eye. Further
rotation would cause tearing of the eye.
[0062] The dissector blade is then rotated in an opposite direction
so to remove the dissector blade (66) from the channel it has just
produced. We have also found it desirable to complete the
interlamellar channel by using another dissector barrel which
rotates in the opposite direction.
[0063] The ICR may be introduced as described below.
[0064] The circumcorneal vacuum ring may be produced in a variety
of desired arrangements. For instance, in FIGS. 10 and 11, a
multi-chambered device is shown. In FIG. 10, a bottom view of the
support base (86) is found. The circumcorneal vacuum ring is made
up of three distinct chambers (88), each of which are connected to
the vacuum source line opening (90). This variation is desired when
additional support is needed between the outer support base wall
(92) and the support base inner bore (94). Because the force
applied to the eye is proportional to the area subjected to vacuum
on the front of the eye, this variation can be used to additional
area under vacuum to the device without trauma to the eye. As may
be seen in FIG. 11, the various interior walls (96) are of a
different height allowing them to conform to the front of the
eye.
[0065] FIGS. 12 and 13 show, respectively, a bottom view and a side
partial cross-sectional view of another variation of the support
base (98) in which the circumcorneal vacuum ring does not
completely encircle the cornea. This configuration allows the
viewing port (as shown in FIG. 3 as (55)) to be quite large and
allows the surgeon views of the cornea both from above through the
inner bore of the dissector barrel or through the side viewing port
during the production of the inner stromal channel. Specifically,
the open part of the channel meets the eye at surface (100) and the
vacuum source line opening provides a vacuum source to the opening
which fits against the eye. Support base (102), as is shown in
FIGS. 14 and 15, is a multi-chamber device analogous to that-found
in FIGS. 12 and 13. The device and added upper chamber (104) allow
the vacuum to more easily circumnavigate the cornea.
[0066] FIG. 16 shows a side perspective cross-section of an insert
(101) which is suitable for inclusion in the lower end of the
support base. This insert has a support ring (105) which may be
metal, stiff plastic or other suitable material. A rubber seal
(103) which fits against the edge is bonded to the support ring
(105). The support ring may have holes (107) inserted therein so to
allow vacuum access when the insert is placed into a support such
as that shown in FIGS. 20-23.
[0067] FIGS. 17, 18 and 19 show three variations of the surfaces
which are desirably used as the surfaces which meet the cornea in
the circumcorneal vacuum ring. Specifically, FIGS. 17-19 are
partial cross-sections of the vacuum chambers showing various edges
of the circumcorneal vacuum chamber where the edges meet the
surface of the eye. Specifically, FIG. 17 shows a variation in
which the circumcorneal chamber (104) has an outer surface (106)
which is disposed at an angle J such that J which is the angle
which a tangent to a patient's cornea would make at that point.
Similarly, inner chamber edge (108) is cut at an angle K such that
the inner chamber edge (108) would lie substantially flat against
the patient's cornea. In FIG. 18, the vacuum chamber (104) has an
outer rounded chamber edge (110) and an inner chamber edge (108)
which is similar in design to the variation shown in FIG. 17. The
FIG. 19 variation uses an outer chamber edge (112) which is
somewhat sharper but is not so sharp as to cause substantial trauma
or cutting of the corneal surface. The inner chamber edge (114) is
of a similar shape.
[0068] The vacuum chamber walls, the circumcorneal rings, and the
support base may be made of a variety of materials including
various plastics, metals, and pliable materials such as natural and
synthetic rubbers.
[0069] The preferred variant of the circumcorneal vacuum ring
contains a number of ridges or vanes which serve to help prevent
rotation of the support base during the ophthalmic operation. There
are a number of suitable ways of introducing such anti-rotating
features. For instance, in FIG. 3, short ridges (116) are included
both in the inner and outer walls of the circumcorneal vacuum ring
(52). The lower terminus of these short vanes (116) rest against
the cornea and after vacuum is applied to the vacuum ring (52), the
cornea is drawn up into the space surrounding the vanes (116) and
the vanes prevent the support base from rotating. FIGS. 20-23 show
other versions of vanes suitable for preventing rotation of the
support base (50). FIG. 20 shows a bottom view of support base (50)
in which eleven vanes (116) are interposed within the circumcorneal
vacuum ring (52). As is shown in partial cross-section of the
rendition shown in FIG. 20, the vanes have several identifying
features. The surface (118) must meet the surface of the cornea
after the suction is applied to the ring. There are pathways
variously through the opening (120) and the stub wall (122) which
allow the vacuum to be distributed from the vacuum line opening
(124) to be distributed evenly about the full circumference of the
circumcorneal vacuum chamber. The pathways for the distribution of
the vacuum around the chamber is not critical. Multiple vacuum
inlets are suitable and other channel shapes are appropriate. FIG.
22 shows still another variation of the vacuum chamber vane (126)
also utilizing a stub wall (122) to allow vacuum distribution. The
vacuum chamber vane (126) uses an additional slot (128) to
distribute the vacuum. Once again, however, the lower surface of
the vane meets flush with the eye and forms small indentations
within the cornea once vacuum is applied.
[0070] FIG. 23 shows a variation in concept for vane shape. The
variation, instead of providing for flat surface against the cornea
instead is stepped in such a way that small points (130) which are
cut into the vane (126) engage the cornea when vacuum is applied to
the device. Vacuum is distributed through hole (120) and in the
spaces formed between outer wall (132) and the lower vane point,
the space between the two vane points (130) and the space between
the upper vane point (130) and the inner wall (134).
[0071] FIGS. 24 and 25 show another variation in which an insert
(136) containing a number of pins (138) may be included as an
integral portion of the support, base (50). FIG. 24 shows a bottom
view of the ring as it is placed within the bottom portion of the
support base (50). The insert ring (136) contains a surface (140)
which serves as the inner wall of the circumcorneal vacuum chamber
(142). In this variation of the invention, pins (138) extend for a
short distance through that sloping wall (140) so that as vacuum is
introduced into chamber (142), the pins engage the eye and
penetrate a short distance into the cornea. The insert ring may
also include slots (142) to allow the vacuum to be distributed
geometrically about the pins with a bit more regularity. The insert
ring (136) may be placed in a chamfer within the interior surface
of support base (50) as is shown in a cross-section in FIG. 25. As
is shown in FIG. 25, the surface of the insert ring which meets the
anterior cornea (140) is, or may be, sloped in the same fashion as
is the anterior wall (108) found in FIGS. 17 and 18. Incidentally,
the outer vacuum chamber wall (144) is shown in cross-section in
FIG. 25 to have a square shoulder. It has been observed that this
configuration causes only minimal trauma when used in this
inventive device with an appropriate amount of vacuum. The trauma
is seen to be even less than that observed with vacuum chamber
outer walls (106) such as is shown in FIG. 17.
[0072] These combinations of vacuum chambers, vanes and ridges
within the vacuum chamber, insert rings with and without pins, all
serve to prevent the rotation of the device during the ophthalmic
operation for which this device is intended. Furthermore, the use
of the insert ring helps to prevent twisting of the corneal surface
during insertion of the dissector blade, as explained below.
[0073] Operation of the Inventive Device
[0074] FIGS. 26-29 show the process for using the combination
device.
[0075] FIG. 26 shows a combination of support base (50) and corneal
centering and fixation guide (62) placed on the front of a
patient's eye (146). The surgeon centers the device on the eye
using reticle (82). At this point, vacuum has not been applied to
the circumcorneal vacuum ring (52). However, as soon as the device
is considered to be centered, vacuum is applied as is shown in FIG.
27 through vacuum source line (58). The amount of vacuum applied is
known. The corneal centering and fixation guide (62) is then
removed from support base (50). It may be observed that within
circumcorneal vacuum ring (52) is a slight bulging of the eye. This
bulging of the eye contacts the vanes within the vacuum chamber;
such vanes are discussed with relation to FIGS. 3, 4, 20, 21, 22
and 23, and the insert ring shown in FIGS. 24 and 25. This contact
with the vanes helps prevent rotation or other movement of the
support base (50). Once the support base is firmly affixed to the
eye, the lance (68) is brought through the window in the support
base to produce a small incision (148) in the cornea. The incision
extends through epithelium and Bowman's membrane and is
approximately 1-2 mm long and about 0.2 mm deep. The incision is on
a radius of the cornea. A small spatula which fits into incision
(148) may be used to make an initial separation in the inner
lamellar layers at the bottom of incision (148) within the stroma.
This "teasing" of the lamella will facilitate the insertion of the
dissector blade (66). It should be noted at this point that the
large viewing port (54) promotes ease of viewing for the surgeon
onto the cornea particularly when used in conjunction with the
large ID bore of the support base (50).
[0076] Finally, dissector barrel (64) is introduced into the
support base (50). The dissector blade (66) is introduced into the
cornea through incision (148) and turned until dissector blade
support arm (84) nears the incision (148). When the support arm
reaches the incision, the rotation of dissector barrel (64) and
attached dissector blade (66), it is reversed and the dissector
blade is backed out of the inner subsurface lamellar tunnel it has
formed. The vacuum is then eased and support base (50) is removed
from the eye. Once the inventive device is removed from the eye,
the ICR (150) may be introduced into the intrastromal channel just
produced desirably with a coating of hyaluronic acid or other
suitable material as a lubricant. The ends of ICR (150) may be
joined using techniques discussed in the patents discussed
above.
[0077] This invention has been described and exemplified in some
detail. Those having ordinary skill in this art would recognize
variations and equivalents which would be well within the scope of
the invention disclosed here but perhaps outside the scope of the
appended claims. It is applicants' intention that these equivalent
variations be included within the scope of this invention.
* * * * *