Use of Patches in Keratectomy Patients

Corneal ulcers in which proteolytic dissolution of the cornea occurs are described as “melting” ulcers or as being affected by keratomalacia. Corneal sequestrum in cats can be associated with feline herpesvirus 1 infection or chronic corneal irritation and usually requires keratectomy with or without corneal graft. The goal of treatment is to retain structural integrity of the cornea with minimal disruption in corneal transparency. In human medicine, bovine pericardial patches (BP) have been evaluated for treatment of corneal wounds.
 
In this study, 3 dogs with keratomalacia and 3 cats with corneal sequestra had BP material placed in the keratectomy bed and sutured with 9-0 polyglactin suture. Systemic and topical antibiotics, systemic NSAIDs, and topical atropine were prescribed postoperatively. Corneal neovascularization was present around the BP graft in all cases after 1 week. At 4 weeks, 2 dogs and all cats exhibited regressing vascularization and the graft was integrating into the cornea, which was regaining transparency. Two months postoperatively, 5 of 6 corneas in 2 dogs and 3 cats had healed with focal corneal scarring. These success rates are similar to those obtained with small intestinal submucosal or amniotic membrane grafts. Based on this study, BP grafts require further evaluation as treatment for infected corneal ulcers but appear to be a promising treatment for corneal sequestra.

This article described the use of BP grafting for reconstruction of the corneal surface. There have been numerous different types of materials employed for this purpose, (eg, autologous corneal, conjunctival, and mucosal grafts; homologous corneal grafts; corneal xenografts; grafts of other tissue types; biosynthetic grafts [ie, porcine small intestinal submucosa, bladder submucosa, renal capsule, amniotic membrane transplants]). To date, all studies on these various materials have compared different indications, clinical scenarios, pre- and postoperative medical therapy, surgical approaches, and subject numbers, making direct comparisons impossible. Most of the studies present seemingly reasonable success rates for the materials they describe, but no material is foolproof or guaranteed to promote or support healing. In general, these materials act as replacement for corneal collagen absent as a result of the disease process or keratectomy. Rather than being dependent on the choice of replacement material used, the prognosis for a particular eye depends to a greater degree on the extent and severity of underlying disease.

The search for an ideal corneal replacement material continues. Rather than debate which material can or should be used, it is probably more important to know and recognize when the use of these materials is indicated.—Caryn E. Plummer, DVM, DACVO

Use of bovine pericardium (Tutopatch) graft for surgical repair of deep melting corneal ulcers in dogs and corneal sequestra in cats. Dulaurent T, Azoulay T, Goulle F, et al. VET OPHTHALMOL 17:91-99, 2014.