Abstract
Purpose: :
Vigabatrin treatment for seizure can cause permanent bilateral concentric constriction of the visual field in 30 percent or more of adult population. Risk increases with the duration of vigabatrin treatment and with total dose of medication. Short term use of vigabatrin has been proposed as a treatment for cocaine abuse. This study aimed to determine the safety of short term vigabatrin use in a clinical trial of treatment for cocaine abuse.
Methods: :
Humphrey Field Analyzer (HFA) 60-4 program was performed in 186 cocaine addicts. Subjects were randomized into two groups: Vigabatrin group (VG, n=92) receiving 3000 mg/day and placebo group (PG, n=94) receiving matching tablets for 12 weeks. Before and post-treatment reliable PVF tests (111 evaluable subjects) were included for the analysis (fixation loss, false positive and negative <33%). The threshold visual sensitivity (TVS) was analyzed by points, rings and zones. Visual field change was considered significant if one of the following occurred: 1. Five or more visual field location points having greater than or equal to 15 dB reduction in threshold sensitivity; 2. Decline (≥ 33% loss) in post-treatment TVS for one or more rings. The Student’s T test or ANOVA was used to compare continuous variables, as appropriate. Fisher’s exact test was used to examine the difference in proportions between groups.
Results: :
All subjects had normal visual acuity, slit lamp and fundus exam on baseline comprehensive ophthalmic evaluation. Reduction in TVS more than 15 dB in five or more visual field location points after treatment was detected in 2/58 (3.45%) of subjects from VG and in 1/53 (1.89%) of subjects from PG (p>0.05, NS). Post treatment reduction of TVS greater than 33% in one or more of the rings and/or in total TVS was present in 4/58 (6.8%) of VG subjects and in 3/53 (5.7%) of PG subjects (p>0.05, NS). Bilateral or concentric visual field change was not detected in any subject exposed to vigabatrin.
Conclusions: :
Short term use of vigabatrin in a clinical trial for cocaine abuse (cumulative dose 218g) did not demonstrate peripheral visual field changes. (ClinicalTrials.gov number, NCT00611130).
Clinical Trial: :
http://www.clinicaltrials.gov NCT 00611130
Keywords: drug toxicity/drug effects • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • visual fields