Apparatus for preparing cornea material for tabbed (sutureless) transplantation

A tool and a method for preparing a donor material used in sutureless corneal transplants uses a first cutting portion to prepare a donor blank having tabbed portions extending outwardly radially. A second cutting portion is used to cut the central portion of the blank. The tool is used as a guide member for the second cutting portion. In one embodiment the tool has slits laterally defined therethrough which allow the tabbed portions of the donor material to be thinned to a desired thickness using a scalpel. In an another embodiment the second cutting portion is a round trephine which is used to simultaneously trim each of the tabbed portions.

BACKGROUND OF THE INVENTION 
This invention relates to the preparation of donor material for a 
sutureless corneal transplantation, and more particularly, to a method and 
apparatus for precisely cutting and preparing the donor material including 
tabs used for transplanting corneas without the use of sutures. 
Corneal transplantation occurs in approximately 37,000 patients in the 
United States each year. In most conventional transplantations, healing of 
the recipient's eye is delayed because of the avascular nature of the 
corneal. The stromal wound healing is facilitated by sutures. However, 
sutures used in many conventional corneal transplants induce astigmatism. 
More recently, a sutureless method for corneal transplantation has been 
developed by Dr. James Rowsey (Rowsey corneal transplant). 
FIG. 1 illustrates the Rowsey corneal transplant using the tabbed 
(sutureless) method. In FIG. 1, a donor material 102 is formed in the 
shape of a partial sphere having a center portion 103 the size and shape 
of a central portion of the cornea of an eye. The center portion 103 has a 
periphery including a downward extending portion 110 and an exterior 
surface 105 in a convex configuration and an interior surface 107 in a 
concave configuration with an essentially common thickness throughout. The 
donor material 102 includes a plurality of corneal tabs 106 extending 
radially from the periphery of the center portion 103. The top (exterior) 
surfaces of the tabs 106 are a continuation of the exterior surface 105 of 
the center portion 103. The exterior surfaces of the center portion 103 
(bordered by dotted lines in FIG. 1) and the tabs 106 are of a common 
Bowman's membrane 108a typically having a thickness of about 100 microns. 
These tabs typically have a thickness of about 10 percent of the thickness 
of the center portion 103 of the donor material. 
Also illustrated in FIG. 1 is the recipient eye 104. The eye 104 is in the 
shape of a partial sphere. The recipient eye 104 is formed with a circular 
aperture 112 at its central portion. The circular aperture 112 is of a 
size and shape corresponding essentially to the periphery of the center 
portion 103 and extending portion 110 of the donor material 102. The 
periphery of the aperture 112 is of a common thickness. The recipient eye 
104 also includes a plurality of symmetrically positioned pockets 114. The 
pockets 114 are incisions made into the thickness of the cornea preferably 
just under the Bowman's membrane 108b of the recipient eye 104 into the 
periphery of the aperture 112. 
To carry out the transplantation, the central portion 103 of the donor 
material 102 is positioned within the aperture 112 of the recipient eye 
104. The tabbed portions 106 are imbricated into the pockets 114 of the 
recipient eye 104. Forceps are preferably used for positioning the central 
portion 103 into the recipient eye 104 and the tabs 106 into their 
respective pockets 114. Although temporary sutures may also be used to 
pull the tabs 106 into the pockets 114, in no instance is it necessary to 
suture the recipient's visual field as is required in conventional 
transplantation techniques. 
Using the above described method, the donor material 102 can be implanted 
into the recipient eye 104 without the use of sutures in the center 
portion 103 of the donor material 102. FIG. 2 illustrates a repaired eye 
with the transplanted cornea. Like reference numerals are used in FIG. 2 
to correspond to those elements illustrated in FIG. 1. As can be seen in 
FIG. 2, the tabbed portions 106 lie within the pockets 114 of the 
recipient eye 104 and are covered by the Bowman's membrane 108b of the 
recipient eye 104. The center portion 103 including the downward extending 
portion 110 of the donor material 102 is placed within the aperture 112 of 
the recipient eye 104. In this manner, a cornea transplant is carried out 
in a more simple and straightforward manner without the need for sutures. 
This method is more fully described in the above-named prior application 
to which benefit of a filing date is relied upon. 
Heretofore, a satisfactory method for preparing the donor material 102 with 
the necessary precision has not been developed. It is extremely difficult 
and time consuming to manually prepare a tabbed donor cornea 102 as 
illustrated in FIG. 1. Moreover, the circle to circle fit from the donor 
to recipient may leave gaps and/or bulges when manual preparation is used. 
The radial placement of the donor tabs would be haphazard at best and each 
implanted cornea would need to be used as the transfer template to prepare 
the recipient eye. This causes the length of time from the donor to 
recipient to increase correspondingly and thereby increase the likelihood 
of damage to the donor material. 
Previous efforts to design a tool to carry out the preparation of the donor 
material 102 have been based on elaborate schemes using plural circular 
cutting blades combined with linear radial extending blades in order to 
prepare the tabbed material having the round center portion and the tabbed 
radially extended portions. Such conventionally suggested tools, however, 
are unworkable in that the precision required to fashion such a tool is 
not practical or possible and have not been seriously pursued. Moreover, 
an extremely important aspect of the sutureless corneal transplant is the 
ability to prepare the tabbed portions sufficiently thin for insertion 
into the pockets of the recipient eye. Conventionally suggested designs 
have not been adequate to accomplish this goal. 
A further difficulty encountered by conventional techniques for preparing 
the donor material, arises from the nature of the donor material to be 
cut. The donor material exhibits properties very much like innertube tire 
rubber. The properties of the material make it extremely difficult to cut 
through the donor material with the precision necessary to prepare the 
tabbed donor form. Accordingly, a tool used to cut the donor material 
should also be designed to support the donor material as it is being cut. 
It is, therefore, an object of the instant invention to provide a tool 
which can be used to create replacement cornea including multiple tabs 
from a donor cornea in a straight forward manner and which is sufficiently 
precise to properly prepare that the donor material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 3A-3D illustrate an apparatus (or tool) used for preparation of the 
donor material 102 (FIG. 1) according to an embodiment of the instant 
invention. As illustrated in FIGS. 3A and 3B, a base 1 is provided to 
support the tool. Guide pins 7 extending up from the base 1 support a 
punch base 2. A punch 8 is held in place within the punch base 2. The 
punch 8 (shown in greater detail in FIG. 3D) has a shape corresponding to 
that of the top surface of the donor material to be prepared. That is, the 
surface on the top end of the punch has a concave spherical radius at its 
center portion 806 and tabbed portions 802 extending radially from a 
central axis of the system and the punch corresponding to the tabbed 
portions 106 (FIG. 1) of the donor material. A nest 3 having a centrally 
located nest hole 310, also having a shape corresponding substantially to 
the desired shape of the donor material, is aligned along the central axis 
and is adapted to receive the punch 8 in the nest hole 310. The nest 3 has 
guide holes 312 located on the periphery of the nest in order to receive 
the guide pins 7. The nest hole 310 is such that the periphery of the 
punch 8 fits closely within the nest hole 310. 
A die 4 is aligned along the central axis to be positioned above the nest 3 
and guided by guide pins 7. The die also has a hole 410 centrally located 
which corresponds to the shape of the donor material. The die 4 is 
provided to cut through the donor material to prepare a donor blank as 
more fully described below. The central portion 411 of the die 4 is 
illustrated in greater detail in FIG. 3C. Portions of an upper surface of 
the central portion 411 of the die 4 act as a lower scalpel guide 401. The 
operation of the scalpel guide will be more fully explained below. The die 
4 is adapted to receive the punch 8 such that the extending tabbed 
portions 802 (FIG. 3D) of the punch 8 are received by the recessed 
portions 402 of the die 4. The die 4 also includes guide holes 412 (FIGS. 
3A and 3B) which are adapted to receive the guide pins 7 for alignment. A 
bottom portion of die 4 which defines the periphery where it intersects 
the hole 410 acts as a cutting edge 422 in combination with a cutting edge 
822 of the punch 8 which is defined by the intersection of the surfaces 
802 and 806 and the vertical outside surface 824 of the punch 8. The 
peripheral clearance between the punch 8 and the die 4 at the recessed 
portions 402 cannot exceed 0.0001". 
A hollow guide member 5 is adapted to be aligned by the guide pins 7 via 
guide holes 512. A downwardly extending cylindrical portion 514 of the 
hollow guide member 5 includes a bottom end 510 adapted to engage and rest 
on a portion of the top surface of the die 4. The hollow guide 5 also 
includes lateral slots 520 through a portion of the bottom end 510 which 
serve to form an upper scalpel guide. The lateral slots 520 in the guide 
member 5 are aligned with the lower scalpel guide 401 (FIG. 3C) of the die 
4. 
A round trephine 6 (FIGS. 3A and 3B) having a round cutting edge 601 on a 
bottom end thereof is received by the guide member 5. The guide member 5 
serves to guide the round trephine 6 to the donor blank material resting 
on the punch 8 after the die 4 has been used to prepare the donor blank. 
The trephine 6 is used to make a circular cut into the donor blank as more 
fully described below. In other words, the cutting edge of the round 
trephine 6 extends through the guide member 5 and out the bottom end 510 
of the guide member 5, which is in contact with the die 4, and cuts into 
the donor material. 
The operation of the device illustrated in FIGS. 3A-3D will now be more 
fully described in connection with FIGS. 3A-3D, 4 and 5A-5K. Prior to use, 
all the instruments should be sterile. Moreover, the corneal tissue should 
not be exposed to any instrument parts which are not at room temperature. 
In operation, the nest 3 is placed on the guide pins 7 and lowered until 
its upper surface 320 is coincident with the periphery of the punch 8. 
This provides a place to rest the donor cornea material in preparation for 
the upcoming operation. The donor material 1020 (in the shape shown in 
FIG. 5A) is placed centrally on the nest 3 with the endothelium facing 
upward. The donor material 102 is secured in place by generating a vacuum 
beneath the material on the punch 108. The vacuum may be produced, for 
example, using a syringe (not shown) connected to produce a vacuum at the 
surface 806 (FIG. 3D) of the punch via holes 804. It is noted that during 
the process, the corneal endothelium cell layer should only be touched in 
those areas which are eventually removed and discarded. 
Once the donor material is in place on the nest 3, the die 4 is installed 
on the guide pins 7 and brought downward until the donor material 1020 is 
cut to produce a donor blank 1021 having the tabbed shape depicted in FIG. 
5C. The scrap portion 162 (FIG. 4) goes down around punch 8 in the nest 3 
and is discarded later. The die 4 descends until the surface of the lower 
scalpel guide 401 (FIG. 3C) is higher than the punch cutting edge 822 
(FIG. 3D) by the thickness of the Bowman's membrane, 100 .mu.m (0.004"). 
In the configuration illustrated in FIGS. 3A and 3B, the die should be 
gripped at the guide pins 7 in order to avoid cocking. 
Once the tabbed blank 1021 (FIG. 5C) is produced and inspected to insure 
correct peripheral cutting, the hollow guide member 5 is assembled onto 
the guide pins 7 (FIGS. 3A and 3B). The hollow guide member 5 is lowered 
until it bottoms out (i.e., comes into contact with the top of die 4). At 
this point the tabbed blank 1021 is resting on the punch 8 with a portion 
of the tabbed blank 1021 extending upward above the top surface of lower 
scalpel guide 401 of the die 4. The guide 5 and the die 4 are shaped such 
that the tabs 1060 of the tabbed blank 1021 are now completely enclosed on 
4 planes by the tool. Specifically, the lower surface 1032 (FIG. 5D) of 
the tabs 1060 is supported by the punch 8. The radially extending sides 
1034 (FIG. 5E) of the tabs 1060 are surrounded by the die 4. The top 
portion 1036 of the tabs 1060 is enclosed by the guide member 5. 
A round trephine 6 is inserted into the hollow guide member 5 FIGS. 3A and 
3B. The round trephine 6 is lowered using an oscillating motion until it 
reaches its lowest point just above the Bowman's membrane, 1062 (FIGS. 4 
and 5G). At its lowest point, the trephine 6 cuts into the stroma between 
the tabs 106 and the central portion 103 of the donor tabbed blank 1021 
down to the Bowman's membrane 1062. Specifically, an incision (or slit) 
1061 is made into the tabbed blank leaving a portion 1062 of the donor 
material beneath the incision intact (FIG. 5G). The thickness of the 
intact portion 1062 is equal to the desired thickness of the tabs 106 
(FIGS. 5I-5K). The trephine 6 is left in place such that the tab stroma is 
now confined on a fifth of the six possible planes by the blade of the 
trephine as illustrated in FIG. 4. 
Using a scalpel 9, positioned by the lateral slots 520 of the guide 5 
forming the upper scalpel guide and the lower scalpel guide 401 of the die 
4, the stroma of the tab 106 is cut away from the Bowman's membrane 1062 
of the donor blank 1021. In this manner, the scalpel 9 is used to trim the 
undesired portion of the donor blank 1021 using the scalpel guide and the 
trephine 6 blade as support for the donor material as illustrated in FIG. 
4. The resultant donor material now has the desired shape as illustrated 
in FIGS. 5I-5K including thin tabbed portions 106. 
Once the donor material is trimmed using the scalpel 9 to produce the donor 
material as illustrated in FIGS. 5I-5K, the scalpel 9, the round trephine 
6 and the guide 5 are removed. The donor material 102 may then be removed 
from the die 4 and has the shape illustrated in FIGS. 1 and 5I-5J. The 
donor material is placed into the recipient's eye as illustrated in FIG. 
2. 
In this manner, the tool of the first embodiment of the instant invention 
is used to prepare donor material for implantation into the recipient eye. 
A tool for preparation of donor material according to a second embodiment 
of the instant invention will now be described in connection with FIGS. 
6A-6D and 7A-7C. 
The second embodiment differs from the first embodiment in the manner in 
which the tabbed portions of the donor material are thinned. In accordance 
with the second embodiment, a two-stage process is employed. The first 
stage of the process utilizes a tool substantially similar to the tool 
depicted in FIGS. 3A and 3B. In the first stage, the donor material is cut 
into the desired shape including the tabs to produce a donor blank having 
cylindrical slits 1061 cut where the tabbed portions 1060 join the center 
portion 1050 as illustrated in FIG. 5G. In other words, a tool similar to 
that depicted in FIGS. 3A and 3B is used to prepare the donor material in 
the desired shape and to cut down into the central round portion of the 
donor material to the desired thickness. The donor material having the 
tabbed shape and the slits cut into the stroma shown in FIG. 5G will be 
referred to hereinafter as a cut donor blank 701. Since a thinning scalpel 
is not used in the second embodiment, it is readily understood that the 
tool illustrated in FIGS. 3A and 3B would not need to include the upper 
and lower scalpel guides 520 and 401 (FIGS. 3C and 4). Otherwise, the tool 
is used substantially as shown therein to prepare the cut donor blank 701 
illustrated in FIG. 5G. 
FIGS. 6A and 6B illustrate a tool for carrying out the second stage of the 
second embodiment of the instant invention. The second stage is for 
removing the stroma material 706 from the tabbed portions 702 of the cut 
donor blank 701 (FIG. 7A). In FIGS. 6A and 6B there is illustrated a base 
602, a castellated nest 604, guide pins 606, a syringe 608, a tab-bender 
610, and a second round trephine 612. The operation of the tool is 
described below in connection with FIGS. 6A-6D and FIGS. 7A-7D. 
The cut donor blank 701 is placed on the castellated nest 604 (FIG. 7A). 
Around the periphery of the top surface 617 of the castellated nest 604 
are a plurality of pillars 614 (castellations) with spaces 616 
therebetween (FIGS. 6C and 6D. The shape of the pillars 614 and spaces 616 
correspond to that of the cut donor blank 701 which rests on the top 
surface 617 of the castellated nest 604 with the tabbed portions extending 
outward radially through the spaces 616 (FIGS. 6D and 7A). A top and side 
view of the castellated nest 604 is illustrated in FIGS. 6C and 6D, 
respectively. As can be seen in FIGS. 6C and 6D, the tabbed portions 702 
of the cut donor blank 701 (dotted lines) extend through the spaces 616 
between the pillars 614 of the castellated nest 604. The cut donor blank 
701 is held in place by suction induced by the syringe 608. As illustrated 
in FIG. 6B, the syringe 608 generates a suction through an air canal 618 
and draws air out of holes 613 (FIGS. 6C and 6D) on the top surface 617 of 
the castellated nest 604. This suction is used to hold the cut donor blank 
in place during the operation of the tab thinning tool 601. 
While the cut donor blank 701 is secured in place by the syringe 608 (FIG. 
7A), the tab bender 610, guided by the guide pins 606, is lowered to the 
base 602 (FIGS. 6A and 6B). As a result, the tabs are bent at an angle of 
approximately 90 degrees to the configuration as illustrated in FIG. 7B. 
It is noted that in this state, the tabbed portions 702 are held in place 
by the stroma 706 of the tabs 702 as the stroma 706 contacts the inside 
wall 721 of the tab bender 610. This operation forces the Bowman's 
membrane 704 of the tabbed portion 702 into contact with the outer wall 
621 of the castellated nest 604. 
Once the tab bender 610 has secured the tab portions 702 in place, a round 
trephine 612 is inserted into the hollow portion of the tab bender as 
illustrated in FIG. 7C in the direction along a central axis 630 of the 
center of the cut donor blank 701. The round trephine 612 is brought down 
in an oscillating motion to cut a portion 707 of the stroma 706 from the 
tabs 702 leaving only the Bowman's membrane 704 on the tabbed portions 
702. As can be understood from the diagram in FIG. 7C, the thickness of 
the remaining part of the tabbed portions 704 is determined as a function 
of the radius R.sub.1 of the outer wall 621 of the castellated nest 604 
(which corresponds substantially to the radius of the first round trephine 
601 used to prepare the cut donor blank 701) and the radius R2 of the 
second round trephine 612 used to trim (or thin) the tabbed members. As 
can be seen, the thickness of the remaining tabbed material 702 will be 
essentially the difference 620 between R1 and R2. The concentricity 
between the second round trephine 612 and the outer wall 621 of the 
castellated nest 604 is critical. The eccentricity should be held to a 
maximum of 0.0002". 
FIG. 7D illustrates an expanded view of the cut donor blank 701 as it 
extends over the castellated nest 604 and is held against the outer wall 
621 of the castellated nest 604 by the tab bender 610 (not shown). While a 
small portion 732 of the stroma will remain on the tab 702 after the bulk 
of the stroma 707 on the tab 702 is cut away by the second round trephine 
612, it does not interfere with the imbrication of the donor material 102 
into the recipient eye 104 (FIG. 1). The thickness of the portion 732 not 
cut away by the trephine 612 is approximately 0.0005" at its thickest 
portion. 
Once the stroma is cut from the tabbed material, the round trephine 612 is 
removed from the device. If necessary, the syringe 608 can be used to hold 
the trimmed tabbed donor (blank) material in place while the round 
trephine 612, as well as the tab bender 610, are removed. 
In accordance with the second embodiment, the tabbed portions of the donor 
material can be precisely thinned to a desired thickness as a simple 
function of the trephine radii (and the castellated nest) and does not 
require an exceptional skill on the part of the surgeon operating the 
tool. 
The instant invention is not limited to the apparatus and methods 
illustrated in the above-described embodiments. Modifications, without 
departing from the scope of the inventive features therein, will be 
apparent to one of ordinary skill in the art having reviewed the above 
description. Accordingly, the instant invention is not limited to the 
embodiments described above and is only limited by the appended claims.