Is visual field constriction in epilepsy patients treated with vigabatrin reversible?

OBJECTIVE: To evaluate the reversibility of vigabatrin associated visual field constriction.
BACKGROUND: Visual field constriction (VFC) occurs in approximately 40 % of epilepsy patients under treatment with vigabatrin (VGB). There is still controversy about whether VGB-associated VFC is reversible. From a cross-sectional study there is evidence that VFC does not reverse three to six months after stopping VGB treatment. So far, there are no long term studies on this subject.
METHODS: We performed a follow-up study on 15 epilepsy patients (eight women, seven men, median age 45 (21-58) years) with VGB-associated VFC but otherwise normal ophthalmological examination. Kinetic and static perimetry was performed one and two years after VFC was diagnosed (baseline examination). Visual field size at first and at second year-follow-up was compared with the baseline examination. Because discontinuation of VGB-treatment was dependant on clinical needs, patients either stopped VGB treatment before or after VFC was diagnosed. In a small group of patients VGB treatment was continued despite of VFC.
RESULTS: There was no statistically significant difference in visual field size comparing baseline values with first year and second year follow-up examinations either in patients who stopped VGB treatment (n = 11) or in patients who continued VGB treatment on a reduced dosage (n = 4).
CONCLUSION: Although our data are based on a relatively small group of patients there is evidence that VFC resulting from VGB treatment is not reversible in epilepsy patients after stopping the drug.