CORNEAL REPAIR

The focus of corneal perforation management should be on prevention, but there are multiple surgical options available for intervention should perforation occur, said Christopher Rapuano MD.

Speaking during the 1st Cornea Day at the 26th Asia-Pacific Association of Cataract & Refractive Surgeons Annual Meeting, Dr Rapuano discussed the use of glue, amniotic membrane and various grafting techniques.

“The surgical decision needs to be individualised as do intraoperative and postoperative care,” said Dr Rapuano, director, cornea service, Wills Eye Institute, and professor of ophthalmology, Jefferson Medical College, Philadelphia, PA.

“Remember that medical management is important as well. It should include treatment of the underlying cause for the perforation, use of immunomodulatory and anticollagenase agents as necessary, and discontinuation of medications such as steroids and NSAIDs that can impair healing or promote infection.”

Factors to consider when deciding on a surgical repair technique include the aetiology of the perforation, its size, location and morphology.

Butyl-2-cyanoacrylate glue is best used for concave, sterile, smaller lesions (up to 1.0- 2.0mm) not located at the limbus.

“Glue does not work well for large perforations or descemetoceles, and it tends to dislodge prematurely if used on lesions at the limbus,” said Dr Rapuano, adding that infectious ulcers can be treated with glue once the infection has improved.

Providing user tips, Dr Rapuano suggested that to promote adherence, the glue should be placed with the patient lying under the operating microscope rather than sitting at the slit-lamp, and after debriding the epithelium from the area of application. In addition, the cornea should be dried prior to application so that the glue does not polymerise too quickly, and only enough glue should be applied to fill the perforation.

Polymerisation may take several minutes and surgeons should avoid touching the glue with a cellulose sponge before the glue dries. Once it is set, a bandage contact lens should be inserted.

“There can be a lot of inflammation with the glue, but it will quieten down after the glue comes off,” Dr Rapuano said.

Amniotic membrane can occasionally be used as a substrate for epithelial growth in cases of small corneal perforations. It is placed stromal side down, using multiple pieces as needed to fill in the divot, and may be secured with fibrin glue and/or sutures.

A lamellar keratoplasty or patch graft is typically used for perforations measuring  2.0 to 4.0mm in diameter that are too large to be amenable to glue or amniotic membrane or if the perforation is outside the visual axis where a large penetrating graft is not desirable. A small trephine, such as a dermatology punch, can be used to harvest the donor and to create a similarly sized defect at the recipient site, and the patch graft is sutured into place.

Partial thickness corneal autograft using tissue from the same or fellow eye offers an alternative for management of relatively small, peripheral defects if donor cornea is not available. Dr Rapuano noted that these autografts are best fixed with a suture rather than with fibrin glue.

Lamellar keratoplasty is technically difficult to perform in eyes with perforations since the big bubble technique cannot be used and some stroma remains. In addition, it is not ideal if the perforation is due to an infected ulcer. Nevertheless, Dr Rapuano noted that Donald Tan MD and colleagues reported achieving similar results using deep lamellar keratoplasty compared with penetrating keratoplasty in eyes with severe infectious keratitis.

Penetrating keratoplasty is most commonly performed in cases of large, central perforations. However, this technique is technically challenging since the eye is often soft and inflamed with a neovascularised cornea and moderate iridocorneal adhesions.

Flieringa ring       
Dr Rapuano noted that he likes to use a Flieringa ring whenever possible and especially if the eye is soft. A vacuum trephine is preferred if adequate suction can be obtained because it minimises pressure on the globe and the potential for causing extrusion of intraocular contents.

“With that risk in mind, surgeons may consider placing glue over the perforation temporarily prior to performing the trephination,” he said.

If visualisation is impaired by an opacified cornea, surgeons need to be extra careful to avoid damaging the iris or lens with their scissors. Use of viscoelastic in the anterior chamber can be helpful to separate iridocorneal adhesions. At least two large peripheral iridectomies should be performed in each case to reduce the risk of pupillary block. Surgeons should also aim to remove as much hypopyon as possible.

Other techniques to consider include therapeutic Descemet stripping endothelial keratoplasty, which may be used on rare occasions to seal a small perforation posteriorly, and grafting with scleral tissue on an emergent basis if cornea is not available. In addition, Alio et al. recently described use of autologous solid platelet-rich plasma with an autologous fibrin membrane for temporary perforation closure.

Reference

1. Anshu A, Parthasarathy A, Mehta JS, Htoon HM, Tan DT. Outcomes of therapeutic deep lamellar keratoplasty and penetrating keratoplasty for advanced infectious keratitis: a comparative study. Ophthalmology. 2009 Apr;116(4):615-23.