Abstract:
Vigabatrin [GABA–transaminase inhibitor] has been used for long term epilepsy treatment. Its use has been limited largely due to the observation of irreversible visual field constriction in some patients. Several small studies suggest that vigabatrin decreased and blocked the craving for cocaine and/or methamphetamine. The purpose of the study is to evaluate visual field effects of short–term use of vigabatrin to treat cocaine and/or methamphetamine addiction. Subjects who were enrolled in an open–label 9 week study of vigabatrin treatment for cocaine and/or methamphetamine addiction performed visual field testing (Humphrey 60–4) at baseline, 1 week, 4 week, 9 week, and 1 month or more after stopping vigabatrin. The study was approved by the local government agency, and all subjects provided informed consent. Visual fields were evaluated subjectively by two glaucoma specialists experienced in reading visual fields, and objectively by grading the change in total sensitivity per quadrant. Superior field quadrants were also analyzed after adjusting the total sensitivity by excluding the uppermost peripheral tested points. All subjects underwent a comprehensive eye evaluation at the beginning and end of the study. Forty–two subjects were enrolled. Eighteen completed the study with full follow–up and reliable visual field testing. No visual field constriction was observed in 18/18 subjects by subjective evaluation. Quadrant scores did not decrease in any quadrant (Table). No changes in visual acuity or ocular adverse effects were noted.In this pilot study vigabatrin was used safely with no evidence of ocular or visual field adverse effects. This drug appears promising as a treatment for cocaine and methamphetamine abuse.
Keywords: visual fields • drug toxicity/drug effects • pharmacology