Histopathologic evaluation of optic neurotomy with microvitreoretinal blade or excimer laser in cadaver eyes. 
To evaluate histopathologic features of optic neurotomy with microvitreoretinal (MVR) blade or excimer laser.  Optic neurotomy was performed in 11 cadaver eyes using a 20-gauge MVR blade and 3 cadaver eyes with pulsed xenon chloride excimer laser.  Hematoxylin-eosin stained slides were used to evaluate the posterior segments of the globes, including the optic nerve head.  No eyes in the MVR group had scleral macroscopic or microscopic perforation and there was no injury to the central retinal vein or artery.  The distance between the neurotomy site and the central retinal vessels ranged from 50 to 500 microm at all histologic levels in 10 eyes and was approximately 10 microm in two histologic sections and 200 microm in a third section in 1 eye.  Intraneural hemorrhage was found in 11% of eyes.  Neurotomy was successful in 2 of 3 eyes with the excimer laser and no neurotomy was evident on sectioning in the third eye due to cloudy media.  Optic neurotomy with an MVR blade was an effective procedure for scleral outlet relaxation in cadaver eyes, with no significant surgical complications.  This preliminary study also demonstrates that the excimer laser can make non-mechanical cuts with relative ease and reliability.