A prospective study of 29 children treated with vigabatrin (VGB) as add on therapy for epilepsy included ophthalmic examination before and at 6-month intervals for 6.5 years, at Sultan Qaboos University Hospital, Sultanate of Oman. Age of onset of seizures ranged from birth to 5 years (mean, 13 months). Of 21 fulfilling study requirements and follow-up, 6 had West syndrome, 3 had Lennox Gastaut syndrome, and the remainder, partial or mixed seizures. Eighty percent had psychomotor retardation. Dose of VGB was 25-114 mg/kg/day (mean 56 mg) and treatment duration was 6-85 months (mean 36 mos). Four (19%) taking 25-50 mg/kg/day for 33-81 months developed retinal pigmentation, hypopigmented retinal spots, and optic atrophy. Visual evoked potentials, performed in 21, were abnormal initially in 2 and became abnormal during VGB therapy in 14. Electroretinography and electro-oculography were not available. [1]
COMMENT. Regular eye examination including perimetry is recommended in patients treated with vigabatrin. Infants with epileptic syndromes and mental retardation, in whom perimetry is not appropriate, should receive funduscopic examination at least every 3 to 6 months, and retinography, electro-oculography, and VER when available. Retinal changes and visual field constriction associated with VGB can be irreversible, and risks may outweigh benefits if alternative less toxic treatments are available. (see Ped Neur Briefs Dec 2001;15:94-95).