Abstracts

RATIONALE: A high frequency (20-40%) of specific visual field defects (VFDs) has been observed in adults after vigabatrin (VGB) treatment. Most patients are asymptomatic, and VFDs have only been detected in perimetry assessment (Goldman or Humphrey). The data on children treated with VGB are limited. We report our experience of 60 VGB treated children and adolescents assessed by a Goldman perimetry. METHODS: Starting in January 1998, VFs of all patients who have been treated with VGB and who are able to co-operate in the Goldmann perimetry test are assessed. At the end of April 2000, 60 out of 241 were examined; 39 of them at least twice and 22 three times or more. Three patients who had received VGB less than two months and four patients whose all examinations were considered unreliable were excluded. Patients with abnormal findings also underwent a neuro-ophtalmological examination. RESULTS: At the first Goldman test, the mean age of the patients was 13.5 years (range 7 and 20 years). All patients had received drug combinations. The maximum dose of VGB ranged 25-125 mg/kg/day. The average total amount of VGB received was 1560 g (range 7-10075 g) per patient. In the first examination, 41 patients had normal VFs. At the first perimetry two patients and at the latest perimetry three patients had typical VFDs (hemianopia and upper quadrant defect) resulting from epilepsy surgery. Of the other 10 patients with abnormal VFs at the first examination, four showed severe or moderate and six only mild or borderline constrictions. Six of these 10 patients had normal VFs in later examinations and four showed mild or borderline constriction. None of the patients showed bilateral nasal VFDs previously found after VGB exposure. Only 4 patients (7%) showed defects were VGB could have been a contributing factor. Two of them had received VGB only for a short time (cumulative dose 30 g and 300 g, respectively). All VFDs observed were either mild (2) or improved during follow-up (2). CONCLUSIONS: Based on our results, VGB treatment of children and adolescents has a lower risk for VFDs than what has been reported in adults.