Noncontact and contact pars plana transscleral neodymium: YAG laser cyclophotocoagulation in postmortem eyes.

Transscleral neodymium:YAG (Nd:YAG) laser energy (5 J), noncontact at 20 msec and contact at 0.5 sec exposure time, was applied to enucleated porcine and human eyes 3 mm posterior to the limbus. Coagulative pars plana lesions were noted in all cases. Related to focus and exposure time, noncontact lesions were larger, more homogeneous, and affected primarily the pigment epithelium, whereas contact lesions showed more full-thickness thermal effects, including sclera. Because the corona ciliaris was unharmed when laser applications were made 3 mm from the limbus, this commonly used clinical focus raises questions about cyclo "destruction." Future clinical research will have to show which phenotype of pars plana lesion correlates best with long-term lowering of pressure.