INFLUENCE OF EXPOSURE TIME ON INFLAMMATORY RESPONSE TO NEODYMIUM - YAG CYCLOPHOTOCOAGULATION IN RABBITS

Objective: To evaluate the influence of duration of exposure on the in flammatory response to transscleral neodymium:YAG cyclophotocoagulatio n. Methods: Transscleral cyclophotocoagulation was performed with a co ntact, Nd:YAG, continuous-wave laser on one eye of 48 Dutch belted rab bits, 10 W and 0.2 second used in half and 1 W and 2 seconds in the ot her half. One third of each group was evaluated on the operative day a nd the other thirds on postoperative days 3 and 10. Tissue reaction wa s inspected grossly and by light microscopy, and inflammatory response s were measured by aqueous leukocyte and erythrocyte counts, aqueous a nd vitreous protein levels, aqueous prostaglandin levels, and iris and ciliary body myeloperoxidase activity. Results: The shorter-duration protocol was associated with more ciliary epithelial disruption and si gnificantly greater inflammatory responses by one or more of the measu res at all times. Conclusion: When energy is constant, a shorter durat ion of exposure with transscleral Nd:YAG cyclophotocoagulation in rabb its is associated with greater tissue disruption and inflammation.