Cannulated Optic Nerve Implants Are Biocopatible in Pig Eyes: A New Drainage and Drug Delivery System

Abstract

Purpose: : In a previous studies we evaluated histopathology features of a plastic optic nerve canula in rabbit eyes. (Invest Ophthalmol Vis Sci 2004;45: E-Abstract 5222) and a metallic grade cannula. (Invest Ophthalmol Vis Sci 2006;47: E.Abstract 4601). In the present study we evaluate biocompatibility of a different metallic optic nerve cannulated implant (MONCI) in pig eyes.

Methods: : Seven pig eyes were implanted with two different designs of MONCI. One design was A) 460 microns in diameter and 2mm long and B) 250 microns in diameter and 3mm long. In all eyes implants were placed after pars plana vitrectomy, at the nasal part of the optic nerve avoiding major vessels and penetrating the lamina cribrosa. Complete eye examination and fundus photography were performed every 3 days up to 1 month when enucleation was done for histopathology examination.

Results: : There were no complications in the procedure. Perforation of the lamina cribrosa with the MONCI was performed easily. Hematoxylin and eosin (HE) staining showed minimal infiltration of lymphocytes and plasma cells that could be attributed to surgical trauma. Both HE and scanning electron microscopy showed preservation of the normal architecture of optic nerve.

Conclusions: : MONCI placed in the optic nerve in pig eyes appears to be biocompatible at one month follow up. Future designs for drug delivery system and aqueous humor shunting between the vitreous cavity to the subarachnoidal space and orbit deserves to be explored.

Keywords: vitreoretinal surgery • optic nerve