Wound leakage rates of ex vivo uniplanar versus biplanar phacoemulsification clear corneal incisions in dogs

OBJECTIVE: The purpose of this study was to compare the leakage rates of perilimbal uniplanar and biplanar clear corneal incisions in dogs when subjected to increased intraocular pressure (IOP) both from within the eye and via external pressure. PROCEDURE: Uniplanar clear corneal incisions were created in eight freshly enucleated canine eyes using a 3.2 mm straight slit knife while 8 fellow eyes received a biplanar clear corneal incision consisting of an approximately 300 mum deep groove followed by a 3.2 mm straight slit knife entry into the anterior chamber. Both wounds were reapposed using three simple interrupted 8-0 polyglactin 910 sutures. Eyes were cannulated with two 25 g needles: One connected to a pressure transducer, and the other connected to a reservoir of isotonic saline. The IOP at which the wound leaked was recorded when the intraocular pressure was increased internally by raising the height of the fluid bag, and again when the cornea was externally compressed. Kaplan-Meier survival curves compared incision types for each method of increasing IOP and were evaluated using Mantel-Cox log-rank analysis. RESULTS: Both wound types resisted leakage at IOP in the physiologically achievable range and no significant differences were observed between clear corneal incisions when pressure was applied externally (P = .353) or was increased from within the globe (P = .615). CONCLUSION: Ex vivo uniplanar and biplanar clear corneal incisions in dogs are equally strong, with no significant differences in leakage rates when IOP is increased internally or externally.