Contact and Noncontact Transscleral Neodymium: Yag Laser Cyclophotocoagulation in a Rabbit Model

PurposeContact versus noncontact transscleral neodymium:YAG laser cyclophotocoagulation was compared in a rabbit model with respect to the effects on intraocular pressure and pathologic findings.MethodsThirty-two rabbits received comparable energy levels (2 joules) of contact and noncontact cyclophotocoagulation. Pneumotonometry was performed every other day following treatment.ResultsFor both the 2-week and 8-week periods following treatment, intraocular pressure was significantly lower in eyes receiving contact cyclophotocoagulation than in eyes receiving noncontact cyclophotocoagulation (for the 2-week period, mean difference in intraocular pressure was 5.3 mm Hg, n = 22, p < 0.001; for the 8-week period, mean difference in intraocular pressure was 4.3 mm Hg, n = 17, p < 0.013). Pathologic findings include acute ciliary body hemorrhage and inflammation (1 day), chronic inflammation (1 week), granulation tissue within laser lesions (2 weeks), and marked ciliary body atrophy (8 weeks).ConclusionsIn our rabbit model, contact cyclophotocoagulation was more effective in lowering intraocular pressure than noncontact cyclophotocoagulation. Both contact and noncontact cyclophotocoagulation produced a variety of pathologic lesions in the rabbit eye, including cataract, phthisis bulbi, and anterior synechiae.