Masoud Soheilian, MD (Tehran, Iran), Mojgan Rezaei Kanavi, MD (Tehran, Iran), Shahin Yazdani, MD (Tehran, Iran), Mohsen Azarmin, MD (Tehran, Iran), Mohammad Hossein Dehghan, MD (Tehran, Iran), Gholam A. Peyman, MD (New Orleans, LA)

PURPOSE:

To evaluate the histopathologic features of optic neurotomy with microvitreoretinal (MVR) blade and excimer laser.

METHODS:

Optic neurotomy was carried out in 11 cadaver eyes using 20-gauge MVR blade and in three cadaver eyes with pulsed xenon chloride (XeCl) excimer laser with a wavelength of 308 nm via monofile lightconducting fiber with a core diameter of 200 microns. After tissue processing, hematoxylin and eosin (H&E)- stained slides were used to evaluate the posterior segments of the globes, including the optic nerve head.

RESULTS:

None of the cases in the MVR-induced neurotomy group had scleral macro- or microperforation and no injury was induced to the central retinal vein or artery. In ten cases, the distance between the neurotomy site and the central retinal vesselsranged from 50μ to 500μ at all histologic levels. In one remaining case this distance was approximately 10μ in two histologic sections and about 200μ at a third level. Intra-neural hemorrhage was found in 11% 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 excimer laser can make non-mechanical cuts with relative ease and reliability. Note the site of radial optic neurotomy is away from central retinal vessels on H&E staining. Intra-neural hemorrhage (asterisk) is presented adjacent to incision at (Magnification x 25). Note the excimer laser-induced overlapping holes (arrow) at the optic nerve head on H&E staining. An artifactual cleft (asterisk) is noted temporal to central retinal vessels (Magnification x 25).