CORNEAL ENDOTHELIAL DAMAGE BY AIR BUBBLES DURING PHACOEMULSIFICATION

Objective: To characterize the mechanism by which air bubbles damage t he corneal endothelium during phacoemulsification. Materials and Metho ds: A series of experiments was conducted to expose the corneal endoth elium of New Zealand white rabbit and human eyes that were obtained fr om an eye bank to air under different conditions. Phacoemulsification at different power settings and irrigation with and without the introd uction of air into the anterior chamber were performed. Corneal endoth elial perfusion experiments were conducted with air bubbles that were introduced into the perfusion chamber for 2 seconds to 1 hour. Air was also injected into the anterior chambers of anesthetized rabbits for 2 minutes to 3 hours. Corneas were stained with nitrobenzoxadiazole-ph allacidin and examined with fluorescence microscopy. Selected corneas were also examined with scanning and transmission electron microscopy. Results: Intracameral air bubbles during phacoemulsification, irrigat ion, and perfusion studies resulted in a severe injury to the corneal endothelium in as little as 20 seconds. Intracameral air bubbles in a living rabbit resulted in a slower injury that was morphologically dif ferent from the more rapid injury. Conclusions: Air bubbles in intraoc ular fluids with a high surface tension can cause a ring-shaped patter n of damage to the corneal endothelium. The mechanism that caused this pattern of damage appears to be a surface tension phenomenon.