[Histopathologic evaluation of optic neurotomy with MVR blade and excimer laser in cadaver eyes]

To evaluate the histopathologic features of optic neurotomy with microvitreoretinal [MVR] blade and excimer laser in cadaver eyes. Optic neurotomy was performed in 11 cadaver eyes using 20-gauge MVR blade and in three cadaver eyes with pulsed xenon chloride [XeCl] excimer laser [308 nm] via monofile lightconducting fiber with a core diameter of 200 microns. After tissue processing, hematoxylin and eosin stained slides were used to evaluate the posterior segment of the globes, including the optic nerve head. None of the cases in the MVR neurotomy group had scleral macro- or micro-perforation and no injury was induced to the central retinal vein or artery. In 10 cases, the distance between the neurotomy site and the central retinal vessels ranged from 50 to 500 micro at all histologic levels. In one remaining case this distance was approximately 10 micro on two histologic sections and about 200 micro at a third level. Intra-neural hemorrhage was found in 18% of cases. Neurotomy was successfully induced in two of three cases attempted with the excimer laser. In one case, due to cloudy media, it was not apparent whether the laser successfully induced the neurotomy and no neurotomy was evident on sectioning. MVR induced optic neurotomy is an effective procedure to create scleral outlet relaxation, without significant surgical complications such as scleral perforation or central retinal vascular injury. This preliminary study also demonstrates that the XeCl excimer laser can make nonmechanical cuts with relative ease and reliability

Ciliary body destruction and retinopexy using diode laser

Semiconductor lasers are recently finding increased application for the treatment of ophthalmic disorders. We used a diode laser with an output power 1 W through a fiberoptic light pipe [200 [micro]m diameter] to deliver laser energy through the scalera of pigmented rabbits. Ciliary body destruction occurred with energy levels of 300-400 mW and exposure time of 0.5 sec. Retinal photocoagulation was achieved with energy levels of 200-500 mW in 0.5 sec. Histologic examination of acute lesions demonstrated thermal destruction of ciliary body processes and retina. Chorioretinal scar formation was observed clinically and histologically within 2-3 weeks. Our data indicate that the transscleral diode laser may be used for destruction of the ciliary body processes or peripheral retinal coagulation in pigmented eyes