Visual field loss associated with vigabatrin: quantification and relation to dosage.
OBJECTIVE
To describe the correlation between visual field loss and the duration, dosage, and total amount of vigabatrin (VGB) medication in a group of patients with epilepsy. Co-medication of antiepileptic drugs (AEDs) and compliance were also studied.


METHODS
Ninety-two patients (53 male and 39 female) taking VGB medication in the past or the present, attending the Outpatient Epilepsy Clinic in Utrecht, were examined with the Goldmann perimeter. The amount of visual field loss was calculated by the Esterman grid method and by a new method, with which the percentage surface loss of the visual field is measured. A complete drug history was compiled, specifying the amount and duration of VGB medication. Concomitant AED medication was noted. Serum levels of AEDs were determined.


RESULTS
Linear regression showed the total amount of VGB as the most significant parameter to predict visual field loss (p < 0.001). Further, men were more affected than women (p = 0.026). Compliance was good, and other AEDs did not influence the results.


CONCLUSIONS
Because prolonged use of VGB medication is correlated with the amount of visual field loss, VGB should be prescribed only when there are no alternatives. In such cases, we recommend an examination of the peripheral visual field before starting therapy and a repeated examination every 6 months.
Hardus
P
P
Departments of Ophthalmology, Academic Hospital Groningen, P.O. Box 30.001, 9700 RB Groningen, The Netherlands. p.l.l.j.hardus@ohk.azg.nl
Verduin
W M
WM
Engelsman
M
M
Edelbroek
P M
PM
Segers
J P
JP
Berendschot
T T
TT
Stilma
J S
JS
D000328:Adult; D000553:Ambulatory Care; D000927:Anticonvulsants / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D004827:Epilepsy / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008297:Male; D010349:Patient Compliance; D012044:Regression Analysis; D012737:Sex Factors; D020888:Vigabatrin / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D014786:Vision Disorders / Q000139:chemically induced* / Q000175:diagnosis* / Q000517:prevention & control; D058609:Visual Field Tests / Q000706:statistics & numerical data; D014794:Visual Fields / Q000187:drug effects*
D000927:Anticonvulsants; D020888:Vigabatrin