SUBRETINAL MICROSURGERY WITH GRADIENT-INDEX ENDOSCOPES

State-of-the-art subretinal surgery involves a standard three-port par s plana entry, followed by an iatrogenic retinotomy to access the subr etinal space. Subretinal manipulations through a small retinotomy are made possible by specially designed instruments. As the surgeon looks through the vitreous cavity, all subretinal maneuvers are obscured by the overlying retina. Consequently, the surgeon is operating 'bindly' and has to rely on 'feeling' rather than direct visualization. Micro-e ndoscopic viewing systems are the ideal solution for visualization dur ing subretinal surgery. Until now, such endoscopes were either too lar ge for intraocular use or lacked sufficient resolution, especially at a short working distance. Recently, a gradient index (GRIN) endoscope was developed (Insight Instruments, Inc., Lake Mary Fla., USA) combini ng a small diameter (0.89 mm, 20 gauge) and incorporating excellent op tical resolution, even at extremely close working distances. After bal looning a limited part of the retina without creating a retinal hole, the 20-gauge GRIN endoscope can be introduced into the subretinal spac e through the sclera and choroid, posterior to the pars plana. Surgica l instruments can then be introduced into the subretinal space through a second neighboring sclerotomy. Thus, subretinal surgery can be perf ormed under direct endoscopic control. As a result of direct visualiza tion, the surgeon may perform certain surgical procedures with greater accuracy, i.e., subretinal neovascular membranes may be dissected met iculously from the neurosensory retina and retinal pigment epithelium, minimizing damage to both structures. The feeding choroidal vessel ca n be identified and directly coagulated, which is usually very difficu lt during conventional subretinal surgery. Endoscopic subretinal surge ry is thus a significant improvement over conventional methods, avoidi ng the need for a retinotomy and increasing the safety and facility of the surgery itself.