Purpose: Bilateral visual field constriction has been reported following the use of the antiepileptic drug (AED) vigabatrin. The incidence of retinal toxicity is variable and there are limited data in Asian populations. The authors report the results of ophthalmologic examination in Chinese patients taking this drug.
Methods: The authors identified two groups of patients with refractory epilepsy: one group on vigabatrin and another cohort of patients taking other AEDs. The authors recorded the medical history and performed visual acuity testing, intraocular pressure measurement, slit lamp biomicroscopy, and conventional automated perimetry with Humphrey Visual Field Analyzer II in all patients.
Results: Eighteen patients--8 men and 10 women--with a mean age of 23.8 years who were taking vigabatrin were reviewed. Length of treatment with this drug ranged from 13 months to 5 years and the mean daily dosage was 1581 mg. None of the patients in either group had a history of coexisting optic nerve diseases or other neurotoxic drug use. Twenty of 36 (55.6%) eyes of the vigabatrin users showed significant bilateral visual field defects with 80% showing a concentric pattern, compared with none in the control group.
Conclusions: The authors confirmed a high prevalence of visual field constriction associated with vigabatrin in Chinese patients. The use of alternative novel techniques such as measurement of the retinal nerve fibre layer thickness and perimetry may detect early retinal damage and result in even higher incidences. Visual field monitoring is recommended in patients who continue to take this drug.