Abstract:
A method of sealing the corneal incision resulting from cataract surgery is presented. The edges of the incision are maneuvered under a keratoscope until an undistorted corneal surface is obtained. Biological glue is then applied to the maneuvered incision. The seal provides for greatly reduced postoperative astigmatism.

Description:
This application is a continuation-in-part of U.S. patent application Ser. No. 07/807,437, filed Dec. 13, 1991, now U.S. Pat. No. 5,190,057. 
    
    
     FIELD OF INVENTION 
     This invention relates to closing ophthalmic incisions to prevent astigmatism and wound leakage. 
     BACKGROUND OF THE INVENTION 
     Cataract extraction is the most common ophthalmic surgical procedure perform in the United States. During cataract extraction, an incision is made at the edge of cornea followed by capsulorhexis and removal of the nucleus and lens material by aspiration and irrigation or phacoemulsification techniques. For a decade, replacement of the natural lens with an intraocular lens has allowed for improved postoperative vision. However, subsequent closure of the corneal incision by suturing results in surgically induced astigmatism, compromising the improved vision. The suturing procedure requires surgical skill and is time consuming. The surgically induced astigmatism is between one and eight diopters depending on the surgeon&#39;s skill, the size of the incisions and the type of suture used. Presently the amount of time required for suturing is between 15 minutes to 1 hour depending on the skill of the surgeon and technique. Surgically induced astigmatism is not limited to cataract surgery, it also occurs in corneal graft. It has been observed that the tightest sutures produce the greatest amount of astigmatism. The astigmatism requires correction by glasses or contact lenses, otherwise the patient cannot have perfect vision even with the best surgical techniques. 
     Previous methods of managing the surgically induced astigmatism have included selective suture removal, an adjustable running suture technique, external corrective lenses and addition of compressional sutures. 
     The amount and placement of an astigmatism can be observed with a keratoscope, an instrument for observing abnormal curvatures of the cornea. The most common form consists of a disc bearing black and white circles, which, in case of anomalous curvature, appear to be distorted figures instead of concentric circles. A more detailed discussion can be found in the American Encyclopedia and Dictionary of Ophthalmology. Of particular interest is a simple hand held keratoscope which can be used with a slit lamp or in the operating room with the microscope, in use since 1974, called a contact keratoscope. It is made of a clear inner cylinder and a white outer cylinder The white cylinder is engraved with eight lines so that when projected onto a small steel ball, the lines are equal in thickness and equally separated. The contact keratoscope is light in weight and does not noticeably deform the eye when placed on the sclera. It is presently used for surgical correction of high post-keratoplasty astigmatism and thermal wedge resection. A more detailed description and references can be found in Int. Ophthal. 4,3: 177-178, 1981. The keratoscope can be mounted for use with the slit lamp or microscope used during operation. The image projected by the keratoscope can be analyzed by computer. (Such a computer analysis is shown in Duane&#39;s Clinical Ophthalmology, 1990, vol 1., Chp. 64, pg. 7.) It is possible that other methods of measuring the surface topography of the eye could be used with the present invention. 
     Biological glue is a glue derived from fibrinogen, a protein found in the blood which is converted into fibrin during clotting. Fibrin is a white, insoluble fibrous protein which when mixed with thrombin acts as a glue. The fibrin and thrombin are available commercially or the fibrin may be extracted from the patients blood by means of plasmaphoresis (electrophoretic separation of blood components). The fibrinogen can be further concentrated by cryoprecipitation and/or lypholization Since the bond strength is a function of the amount of fibrinogen, a strength tailored to the incision can be made. Thrombin and fibrinogen having a moisture content of less than 3% are available through ICN Biomedicals. This glue has been used in nonsuturable hemorrhage, pancreatic injuries, craniofacial surgery, pluto-pulmonary fistula, nerve repairs, control of pulmonary air leaks, obstetrics and gynecology, heart ventricular ruptures, repair of giant scleral ruptures, dental surgery, plastic surgery, epikeratophakia, perforated corneal ulcers, frontobasal and orbital reconstruction following trauma without complications. 
     After cataract surgery, leakage from the sutured incision can occur. To prevent this a contact lens made from collagen is placed on the eye. Such collagen shields are absorbed by the body after one to three days. 
     Much of the time required for ophthalmic surgery is occupied with suturing. The time for this procedure can be reduced to 5 min. by the technique of the disclosed invention. Other surgical incisions resulting from ophthalmic surgery are conjuntiva-limbus incision during glaucoma surgery, and scleral-tennon-capsule incision during vitreous retinal surgery. 
     It is an object of this invention to provide a method of closing the corneal incision which will minimize postoperative astigmatism, minimize required surgical time and skill, and minimized postoperative complications and recovery times. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of the eye. 
     FIG. 2 is a perspective view of a the clip shown in FIGS. 6-8, in use. 
     FIG. 3 is a top view of a first embodiment of a clip for use with the present invention. 
     FIG. 4 is a side view of the embodiment of FIG. 3. 
     FIG. 5 is a view of a staple for use with the present invention. 
     FIG. 6 is a side view a second embodiment of a clip for use with the present invention in a closed position. 
     FIG. 7 is a side view of the second embodiment in an opened position. 
     FIG. 8 is a top view of the second embodiment. 
     FIG. 9 is a perspective view of a clip having a dissolvable edge. 
     FIG. 10 is a perspective view of a surgical fastener having multiple pins. 
     FIG. 11 shows a set of fastening pins having a pinch anchors. 
     FIG. 12 is a side view of a pin with glue. 
     FIG. 13 is a perspective view of a fastener having glue and multiple pins. 
     FIGS. 14A and 14 B are top and perspective views of a surgical fastening tape with glue. 
     FIG. 15 shows fastening fiber for applying glue to a very small linear area. 
     FIG. 16 is a top view of a glue spatula. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides materials for sealing of the corneal incision after surgery with biological glue under the guidance of a keratoscope 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The cornea is opened for cataract surgery by an incision 1.5 to 2.0 mm away from the limbus. The size of the incision varies according to surgeon preference, the type of intraocular lens to be implanted and the surgical techniques used for removing the natural lens from the eye. 
     After removal of the natural lens and its replacement with an intraocular lens, a keratoscope image of the cornea will be provided. The preferred keratoscopes for the operating environment are the hand keratoscope which is built into the surgical microscope. 
     The surgeon holds the two edges of the corneal incision with two forceps moving them up and down, right or left,until an undistorted pattern is viewed through the microscope-keratoscope. With the edges stabilized in this position, biological glue is applied to the corneal incision, possibly by an assistant, and the edges held for one minute, until the glue has set. The surgeon can make fine adjustments if necessary. 
     If the incision is large, that is, more than 7 mm. one or more fasteners such as shown in FIG. 2 through 14B can be used to hold a portion of the incision closed while a separate section is sealed. Such fasteners would be small, perhaps 1-2 mm in width, and relatively soft so as to not distort the cornea during use or removal. Although the fastener could be made of a soft metal such as gold or a flexible polymer such as an acrylic, it is thought that if a fastener could be made of collagen that removal would be unnecessary. The fastener could also be made of at least 2 materials, for example, a soft acrylic for the tissue gripping area and a metal for the area where pressure is applied. Perhaps fastener having a removable bioabsorbable edge made from a material such as disclosed in U.S. Pat. No. 4,719,917, incorporated herein by reference, or an edge soluble in the glue could be used. Alternatively, but not preferred, a temporary suture could be used. 
     FIG. 3 shows a clip having an upper plate 5, a lower plate 6, an upper pivot shaft support 9, a lower pivot shaft support 10, a pivot shaft 11, and a spring 8. The gripping end of the pin is equipped with two protrusions 12 to grip the tissue, and an recess or opening 7 for accepting the protrusions. 
     FIGS. 6 to 8 show an alternative clip 4 having an angled upper plate 17 and a lower plate 16, interwoven around a pivot shaft 18. 
     FIG. 5 shows a small surgical staple having an arched upper portion 14 and a pointed linear lower portion 15. If made of a resilient material, the ring could be opened over the edges of the tissue, catching one edge at a time, and then allow to resume an unopened position, bringing the edges together. This design would allow the edges to be brought together without being pinched. 
     FIG. 2 shows the clip 4 in use during surgery. The surgeon has grasped the sections of tissue, 1 and 2, with the forceps 3. An assistant then places the clip 4 between the forceps and the surgeon can make further alignment adjustments around the clip. 
     The clip of FIG. 9 is has an absorbable collagen tip 30 at the end of upper 32 and lower 34 legs. The collagen tip 30 is secured to the legs by a water soluble glue such as albumin or a starch based adhesive, so as to detach shortly after use. It is possible that biological glue could be placed on the surface of the clip. If a flexible leg is desired, a soft metal such as gold, a thin polymer such as PMMA, or a soft material such as a silicone based polymer or a hydrogel. 
     The clip of FIG. 10 has a series of small pins 38 fastened to an upper bridge 36. Alternatively very small pins 42 such as in FIG. 11 having a head 40 and flexible pinch assemblies 46 held by a compressible portion 44. These assemblies would be constructed similar to tie tack holders, but much smaller and preferably of a less rigid material. 
     To make the glue, fibrinogen, preferably extracted from the patients blood, is dissolved in saline solution. Commercially available topical thrombin is then added to form the glue. 
     The clip of FIG. 12 has pins 50 extending from relatively flexible legs 48. At the bridge of the clip is a portion of biological glue 52, which can be pressed over the incisions. The glue may be divided into two portions, for example, thrombin and fibrinogen portions one portion being located on the bridge and the other being on the terminals of the pins. To clip and apply glue to a larger section of the incision a multipin unit such as is shown in FIG. 13 could be used. The pins 54 extend from a relatively flexible wall 56. 
     Alternatively a narrow tape such as shown in FIGS. 14A and 14B could be used. The tape would is preferably made from a bioabsorbable polymer. The outside of central portion 60 would be coated with one portion (either fibrinogen or thrombin) of a biological glue and the outside of outer portions 58 coated with the other portion. The tape could be contacted with an aqueous solution to wet and mix the portions at the time of operation, and the be applied to an incision. The tape can be indented in the central portion to better seat the outer coated surface in an incision. Of course, other biologically compatible glues may be used in place of a biological glue. 
     For very narrow incisions a bioabsorbable fiber 62 having powdered thrombin 64 and fibrinogen 66 on its surface, could be contacted with aqueous solution at the time of operation, and be applied to the incision. 
     FIG. 16 show a spatula having powdered thrombin 72 and fibrinogen 70 located on the blade 74 of the located at the terminus of the handle 68. To use the spatula, the biological glue is activated by contacting this with the blade 68 with aqueous solution, and then the glue is applied to the area desired. 
     Fibrin based glue is believed to have some antibacterial action naturally, however, antibiotics may be added to the glue for enhanced antibacterial action. Such direct contact increases the effectiveness of the antibiotics and lowers systemic reactions relative to antibiotics which are given orally or intravenously. 
     The glue could also be used to seal incisions between the conjunctiva and limbus after glaucoma surgery, and for the sclera, tenon, or conjuntiva after vitreous retina surgery or other ophthalmic procedures. Because the sclera is somewhat rigid, it is foreseen that the use of the clips, a temporary suture or a staple might be advantageous. 
     Surgically, incisions closed by the disclosed method would be less costly. Since operating time is reduced, surgeon, anesthesiologist and related fees are reduced. Requirement for corrective lenses would be reduced. Recovery time should be reduced drastically, reducing the number or required postoperative visits and work absence for the patient. 
     Medically the operation would become safer. The glue is safe, and has anastomosis (the union of tissue to form a network) effects on the vessels of the conjunctiva and episclera, preventing bleeding of vessels after surgery. Postoperative wound leakage after cataract surgery would be prevented due to speedy, tight adhesion of the corneal incision. Patching or eye shields might be unnecessary for patient&#39;s eye after surgery. Postoperative vision would be improved. Recovery time would be reduced. The need for collagen shields after surgery could be eliminated, and the amount and duration of postoperative antibiotics would be reduced.