ERBIUM - YAG LASER-SURGERY OF THE VITREOUS AND RETINA

Purpose: These studies evaluated an erbium:YAG laser for transection o f vitreous membranes, retinotomy, and incision and ablation of epireti nal membranes. Methods: Elevated vitreous membranes, detachments, and epiretinal membranes were induced in rabbit eyes. An erbium:YAG laser, emitting at a wavelength of 2.94 mu m and equipped with a flexible fi ber and endoprobes with tips ranging from 75 to 375 mu m, was used to perform vitreous membrane transections, retinotomies, and epiretinal m embrane incisions and ablations in nontransmitting aqueous media with the endoprobe in proximity to the tissue. Ablations of epiretinal memb ranes also were performed in transmitting media, including air and per fluoro-N-octane with the endoprobe elevated above the membrane. Result s: Twenty-five vitreous membrane transections were made in 16 eyes at distances ranging from 0.5 to 4.5 mm from the retina with radiant expo sures ranging from 2 to 50 J/cm(2) with nonhemorrhagic retinal damage in a single transection. Sharp, linear retinotomies were created succe ssfully in five eyes. Epiretinal membrane ablations were performed wit h radiant exposures ranging from 1.8 to 22.6 J/cm(2). In aqueous media , results of microscopic examination showed partial- to full-thickness ablation with a maximum lateral thermal damage of 50 mu m. In air- an d perfluoro-N-octane-filled eyes, there was increased lateral damage w ith desiccation of residual tissue. In 12 aqueous-filled eyes, 18 line ar incisions were successfully performed, with retinal nonhemorrhagic damage in 2 eyes and hemorrhage in 5. Conclusion: The erbium:YAG laser may provide new approaches to maneuvers performed in vitreoretinal su rgery.