title: Symptomatic and asymptomatic visual loss in patients taking vigabatrin.
abstract: OBJECTIVE
  To investigate the clinical, perimetric, and electrophysiologic findings in patients with visual field loss on long-term treatment with the antiepileptic medication vigabatrin.
  
  
  METHODS
  Consecutive observational case series.
  
  
  METHODS
  Forty-one consecutive subjects taking vigabatrin referred for screening ophthalmologic assessment were studied. Twelve subjects with evidence of peripheral visual field constriction are presented.
  
  
  METHODS
  Twelve subjects with evidence of peripheral visual field constriction on 60-4 perimetry underwent central 30-2 and blue-on-yellow (B/Y) perimetry, as well as electroretinography (ERG), electro-oculography (EOG), and visual-evoked potential (VEP) testing.
  
  
  METHODS
  Visual acuity; fundus abnormalities; visual field loss; and ERG, EOG, or VEP abnormalities were the main outcome measures.
  
  
  RESULTS
  Eight of the 12 subjects with constricted visual fields were asymptomatic. The central 30-2 perimetry demonstrated bilateral visual field constriction in 9 of 12 patients and the B/Y perimetry in 8 of 9 patients tested. Of the ten patients tested electrophysiologically, four had abnormal ERGs, five had abnormal EOGs, and three had delayed VEPs.
  
  
  CONCLUSIONS
  The incidence of visual field constriction in patients taking vigabatrin may be higher, and asymptomatic visual field loss more common, than reported previously. The authors postulate a possible Muller cell dysfunction in the peripheral retina. Patients taking vigabatrin should have regular peripheral visual field examinations.
authors.affiliation: The University of Ottawa Eye Institute, Ontario, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Daneshvar
authors.forename: L
authors.initials: L
authors.lastname: Racette
authors.forename: S G
authors.initials: SG
authors.lastname: Coupland
authors.forename: P J
authors.initials: PJ
authors.lastname: Kertes
authors.forename: A
authors.initials: A
authors.lastname: Guberman
authors.forename: D
authors.initials: D
authors.lastname: Zackon
mesh_terms: D000612:4-Aminobutyrate Transaminase / Q000037:antagonists & inhibitors*; D000328:Adult; D000927:Anticonvulsants / Q000009:adverse effects*; D004585:Electrooculography; D004596:Electroretinography; D004791:Enzyme Inhibitors / Q000009:adverse effects*; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020888:Vigabatrin; D014786:Vision Disorders / Q000139:chemically induced* / Q000503:physiopathology; D014792:Visual Acuity / Q000187:drug effects* / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields / Q000187:drug effects* / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000009:adverse effects / Q000031:analogs & derivatives*
chemical_list: D000927:Anticonvulsants; D004791:Enzyme Inhibitors; D005680:gamma-Aminobutyric Acid; D000612:4-Aminobutyrate Transaminase; D020888:Vigabatrin