Vigabatrin toxicity-effects on optic nerve

Introduction

Vigabatrin is an antiepileptic drugwhich is used as the drug of choice in resistant epilepsy and infantile spasms. Cases of visual field constriction have been frequently reported following the use of this drug indicating some involvement of the visual system. Studies have been done on the effects on retina but few are available stating the effects on optic nerves. Hence the present study was designed to study the histopathological effects of vigabatrinadministrationon the optic nerves of albino rats.

Material and Methods

Rats were divided into control and experimental groups. Vigabatrin was administered intraperitoneally to the experimental group in three graded doses for a period of 4 weeks, after which the rats were sacrificed. Brains were dissected out, followed by dissection of the eyeballs along with optic nerves. Slides of optic nervewere prepared for histological examination.

Results

Atrophy of optic nerve and signs of intramyelinicoedema in the form of vacuolation were seen. Features of demyelination were not found in any slide. Severity of the findings increased with increasing doses.

Discussion

Vigabatrin may be toxic to the visual system, especially the optic nerves. We suggest that it should be used with caution and only if required, keeping doses as low as possible. Tests for assessing visual function should be performed during treatment and doses should be adjusted accordingly.