Tissue adhesive for repair of conjunctival buttonhole in glaucoma surgery

Ocular adhesives: Design, chemistry, crosslinking mechanisms, and applications

Closure of ocular wounds after an accident or surgery is typically performed by suturing, which is associated with numerous potential complications, including suture breakage, inflammation, secondary neovascularization, erosion to the surface and secondary infection, and astigmatism; for example, more than half of post-corneal transplant infections are due to suture related complications. Tissue adhesives provide promising substitutes for sutures in ophthalmic surgery. Ocular adhesives are not only intended to address the shortcomings of sutures, but also designed to be easy to use, and can potentially minimize post-operative complications. Herein, recent progress in the design, synthesis, and application of ocular adhesives, along with their advantages, limitations, and potential are discussed. This review covers two main classes of ocular adhesives: (1) synthetic adhesives based on cyanoacrylates, polyethylene glycol (PEG), and other synthetic polymers, and (2) adhesives based on naturally derived polymers, such as proteins and polysaccharides. In addition, different technologies to cover and protect ocular wounds such as contact bandage lenses, contact lenses coupled with novel technologies, and decellularized corneas are discussed. Continued advances in this area can help improve both patient satisfaction and clinical outcomes.

Ocular surface sealants and adhesives

Tissue adhesives, both synthetic and biologic, have a long history of use in ophthalmology. Cyanoacrylate-based glues have traditionally been the most widely used glues for various purposes. They have been specially useful for treating corneal perforations and have had significantly improved long-term outcomes. More recently, fibrin-based glues have gained a major role as a suture substitute for attaching biologic tissues and as surface sealants. The literature supports expanded use of fibrin glue in this fashion. Other new agents, such as polyethyelene glycols, have been underutilized and hold promise, especially as surface protectants. Numerous other glues are being developed and show promise as ocular surface sealants and protective membranes. Advances in knowledge about tissue adhesives are leading to more effective and efficient ophthalmic care.

Bleb reduction and bleb repair after trabeculectomy

OBJECTIVE

To describe methods and outcomes for repair of bleb-related complications of trabeculectomy surgery.

DESIGN

Retrospective, consecutive, noncomparative case series.

PARTICIPANTS

Thirty-one persons having bleb revision by two surgeons at the Wilmer Institute from 1994 to the present.

INTERVENTION

One of two types of revision surgery was performed: bleb reduction to decrease symptoms from large blebs or bleb repair to improve hypotony, using conjunctival rotation flap or free conjunctival autograft.

MAIN OUTCOME MEASURES

Visual acuity, intraocular pressure (IOP), reported symptoms, complications, and number of glaucoma medications at the final visit.

RESULTS

The mean time from trabeculectomy to bleb revision was 4.4 years. Bleb reduction was performed because of symptomatic, high blebs in 11 eyes of 11 persons. Bleb repair was performed to end bleb leakage in 13 eyes of 13 persons and to increase IOP in 8 eyes of 7 persons with hypotony. Median visual acuity improved from 20/50 before revision to 20/30 at most recent follow-up. Mean IOP increased after treatment from 7.7+/-4.9 to 12.4+/-4.0 mmHg (P < 0.001). Symptoms that caused the revision surgery were eliminated in all cases. None of these eyes has lost IOP control, none has required repeat trabeculectomy, and only 2 of the 32 (6%) require topical glaucoma medication. More than one revision procedure was required in 8 of 32 (25%) eyes.

CONCLUSIONS

Surgical bleb revisions for complications after trabeculectomy surgery are safe and effective. Bleb reduction for large, symptomatic blebs or bleb repair for leaking blebs and hypotony did not lead to loss of IOP control.

Control of intraocular pressure after trabeculectomy

Control of intraocular pressure (IOP) is the goal of trabeculectomy, and pursuit of this goal does not end with the completion of the surgical procedure. Proper postoperative management of the trabeculectomy patient requires an understanding of possible events that alter IOP and knowledge of the treatments to control IOP. Recent changes in surgical technique, including the use of antimetabolites, have provided new challenges in the postoperative management of trabeculectomy patients. Interventions are described to restore the flow of aqueous to the filtering bleb in the early postoperative period, to manage flat anterior chambers with both high and low intraocular pressures, to manage a failing filtering bleb, and to manage hypotony. Herein we discuss current methods for controlling IOP in the postoperative period.

Dysfunctional filtering blebs

Guarded filtration surgery, is commonly used to control the intraocular pressure (IOP) in glaucomatous patients. Filtration surgery lowers the IOP by creating a fistula between the inner compartments of the eye and the subconjunctival space (i.e., filtering bleb). There are several options to improve the function of filtering blebs and to prevent their failure. However, improvement of IOP control after guarded filtration procedures is associated with a higher frequency of bleb-related complications. Early (e.g., bleb leak, excessive filtration, flat anterior chamber, filtration failure) and late (e.g., bleb leak, excessive filtration and hypotony, symptomatic blebs, bleb encapsulation, filtration failure, bleb infection) complications associated with filtering procedures should be managed adequately to prevent further problems. Techniques to improve the function of filtering blebs and to treat postoperative complications have progressed over the past decade.

Free conjunctival patch for repair of persistent late bleb leak

In four patients, we repaired leaking blebs by using a new technique of excision of the cystic bleb and replacement with free conjunctival autograft. The leaks were repaired successfully, and bleb function was maintained in all four patients. This technique should be considered when surgical management of a leaking bleb is indicated.

Reconstruction of filtering blebs with free conjunctival autografts

BACKGROUND

Situations arise in which the surgical repair or revision of filtering blebs is either technically impossible or inadequate, and total reconstruction becomes necessary. This is most frequently encountered in eyes that have undergone multiple procedures, resulting in significant bulbar conjunctival scarring and episcleral fibrosis.

METHODS

To preserve the pre-existing filtration site, the authors successfully treated five such patients in whom conjunctival scarring adjacent to and surrounding the blebs precluded local revision, by transplanting free conjunctival autografts. Two patients required grafting from the fellow eye. Specific modifications from previously reported conjunctival flap techniques were used to enhance graft healing and continued filtration.

RESULTS

Satisfactory intraocular pressure control was maintained in all patients receiving minimal to no anti-glaucomatous medications with an average follow-up of 42.6 months (range, 7-90 months). No patient had a significant decrease in visual acuity or surgical complications.

CONCLUSION

Free conjunctival autografting techniques are a useful adjunct in the surgical revision of leaking, failed, or migrating filtration blebs.

Cryotherapy to close a corneal subepithelial aqueous track after trabeculectomy

After filtering surgery for primary open-angle glaucoma in a 64-year-old man, a persistent wound leak was encountered from the fornix-based conjunctival flap. Cyanoacrylate adhesive was applied but was unsuccessful in sealing the leak. The limbal margin was sutured with 10/0 nylon. One week later a corneal subepithelial fistulous track developed from the edge of the bleb and extended across the cornea towards the inferonasal limbus. The inferior end of the track leaked aqueous. Further surgery was performed to refashion the conjunctival bleb, ablate the fistula at its origin and re-form the anterior chamber. The track recurred 16 days later. The upper cornea was then treated with cryotherapy, which successfully closed the track with maintenance of a functional bleb (ocular pressure 6 mmHg). A faint asymptomatic subepithelial scar persisted.

Clinical experience with N-butyl cyanoacrylate (Nexacryl) tissue adhesive

BACKGROUND

To investigate the indications, outcomes, and complications of N-butyl cyanoacrylate tissue adhesive for ocular clinical use. This tissue adhesive is under investigation by the Food and Drug Administration.

METHODS

N-butyl cyanoacrylate was used as an investigational device on 44 patients at the authors' institution over a 2-year period. The charts of these patients were reviewed.

RESULTS

The indications for glue application included corneal perforation (19 eyes), descemetoceles (9 eyes), leaking filtering blebs (6 eyes), stromal thinning (5 eyes), wound leaks (4 eyes), and exposure keratopathy (1 eye). A bandage contact lens was used over the dried tissue adhesive in 38 of the 44 eyes. Length of glue adherence ranged from 1 to 660 days (mean, 72 days). Outcome was penetrating keratoplasty (19 eyes), no further intervention (14 eyes), enucleation (4 eyes), surgical revision of a filter (2 eyes), scleral patch graft (1 eye), conjunctival transplant (1 eye), failed tarsorrhaphy (1 eye), suturing of wound (1 eye), and a lamellar graft (1 eye). Vision improved in 52% (23/44) of eyes.

CONCLUSION

This tissue adhesive may soon be available to all ophthalmologists, and the authors' experience demonstrates that it is an effective method of temporary or permanent closure of an impending or frank perforation.

Closure of leaking filtering blebs with cyanoacrylate tissue adhesive

Five leaking filtering blebs, occurring between 10 months and 21 years after trabeculectomy, were closed with cyanoacrylate tissue adhesive. Filtering bleb integrity was preserved in four cases, so that additional microsurgery was avoided. The only problem associated with use of tissue adhesive was the development of corneal abrasions in three cases. Although it is an accepted treatment for these conjunctival fistulas, only nine previous cases have been reported to our knowledge. We strongly recommend the use of tissue adhesive as a presurgical treatment in the management of leaking filtering blebs which present as a late postoperative complication of glaucoma surgery.