Inflammatory effects of continuous-wave neodymium: yttrium aluminum garnet laser cyclophotocoagulation

The uveal inflammatory response was studied in 31 rabbits treated unilaterally with neodymium: yttrium aluminum garnet (Nd:YAG) cyclophotocoagulation. Fifteen applications of 3.5-J energy were delivered to the dorsal and ventral perilimbal sclera using a contact continuous-wave system. On days 1, 3, 8, and 15, the inflammatory effects were assessed. Peak levels of aqueous humor protein (11 +/- 3 mg/ml), prostaglandin E2 (8.9 +/- 3.0 ng/ml), leukocytes (205 +/- 113/microliters), and iris-ciliary body myeloperoxidase activity (6.32 +/- 1.4 U/mg protein) occurred on day 3 and rapidly decreased between days 7 and 15. Vitreal protein levels also peaked at day 3 but remained elevated through day 15 (3.8 +/- 1.3 mg/ml). By contrast, aqueous erythrocytes were most numerous (22,614 +/- 10,517/microliters) on day 8. Levels of leukotriene B4 remained low in all eyes at all intervals. Correlative histologic changes were ciliary coagulation necrosis, severe vascular congestion, and a predominantly mononuclear inflammatory cell infiltrate. These data suggest that Nd:YAG cyclophotocoagulation in rabbits induces a relatively mild inflammatory response that is associated with significant vascular compromise. Although these observations may not be analogous to the situation in the human eye, they may provide a model with which to compare the relative effects of different treatment parameters to help establish the optimum protocol.