Abstract
Abstract: :
Purpose: To compare the efficacy of human amniotic membrane to bandage contact lens and conjunctiva in the prevention of corneal melt and perforation after a severe (Grade IV) chemical injury. Methods: A unilateral alkaline burn was induced in the right eye of 32 New Zealand white rabbits by filling a 15mm diameter plastic well placed on the corneal and limbal surfaces with 0.2ml 1N NaOH. After 20 seconds the alkali was aspirated and the eye rinsed with 2L of sterile saline. The rabbits were then divided into 4 groups of eight with the following acute interventions: Control, Bandage Contact Lens with tarsorrhaphy, Conjunctival graft, and Amniotic Membrane graft. Topical administration of Maxitrol ophthalmic drops to the operated eye of all rabbits was carried out at three times a day for 2 weeks postoperatively. The amniotic membrane, conjunctival flap, and bandage contact lens/ tarsorrhaphy were removed at one month post–operatively. The integrity of the corneal surface was documented at postoperative days 30 and 60 with a standardized 35mm operating microscope camera. These results were analyzed by two masked observers. Results: After the chemical injury, all four groups showed similar degrees of corneal opacification and limbal ischemia. All incidences of corneal perforation occurred after 3 weeks postoperatively. At 60 days, only 2 eyes (25%) from the amniotic membrane group had perforated versus 7 (88%) in the conjunctival group (p< 0.025). This is in contrast to 3 (38%) perforations in the bandage contact lens group and 4 (50%) in the control group. Conclusions: Amniotic membrane is more effective than conjunctiva in preventing acute corneal perforation after a grade IV chemical injury. The thickness of the conjunctival graft may have prevented adequate corneal oxygenation and penetration of topical steroids thereby leading to an increase in inflammation and subsequent perforation. In severe chemical injuries, amniotic membrane may have a protective role against progressive corneal melting and perforation especially if used in conjunction with other therapies.
Keywords: cornea: epithelium • trauma • wound healing