The effect of air tamponade on the ingress of ocular surface pathogens in sutureless transconjunctival microincisional vitrectomy

PURPOSE: To assess the effect of air versus fluid tamponade on the intraocular migration of india ink particles through nonsutured transconjunctival 23-gauge sclerotomies in living porcine eyes. METHODS: Both eyes (n = 20) underwent 3-port, transconjunctival, 23-gauge vitrectomy. An angled trocar insertion technique was used in all cases. In each animal, one eye underwent a partial fluid-air exchange at the conclusion of the vitrectomy, yielding an air fill of approximately 80% (n = 10), whereas the other was left fluid filled (n = 10). After removal of the instruments and trocar cannulae, india ink was applied to the ocular surface. Animals were allowed to partially recover from anesthesia and resume normal blinking behavior. Animals were then reanesthetized, euthanized, and enucleated. Histopathologic examination was performed in a masked fashion. The presence and location of ink was noted for each identified sclerotomy. RESULTS: Ink was identified on the ocular surface in 18 of 20 eyes. Sclerotomy wounds were identified in 16 of 20 eyes. Ink penetration was seen in 2 of 16 sclerotomy wounds, 1 in an air-filled globe and 1 in a fluid-filled globe. In both eyes, the ink was identified along the outer one third of the wound. There was no penetration of ink along the inner two thirds of the sclerotomy wound or in the posterior segment of any eyes. CONCLUSION: In an experimental, in vivo, porcine model, india ink migration into angled transconjunctival sclerotomy incisions was minimal, regardless of the use of an 80% fluid-air exchange at the conclusion of the case.