histopathologic evaluation of optic neurotomy with mvr blade and excimer laser in cadaver eyes

purpose: to evaluate the histopathologic features of optic neurotomy with microvitreoretinal (mvr) blade and excimer laser in cadaver eyes. method: 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 light-conducting 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. results: 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 m at all histologic levels. in one remaining case this distance was approximately 10 m on two histologic sections and about 200 m 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. conclusion: 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 non-mechanical cuts with relative ease and reliability.