title: Evolution of visual field loss over ten years in individuals taking vigabatrin.
abstract: OBJECTIVE
  Vigabatrin-associated visual field loss (VAVFL) occurs in around 45% of exposed people. It is generally accepted that, once established, VAVFL is stable and does not progress with continued VGB use. Most studies have, however, only followed people for short periods. We assessed the evolution of VAVFL over a ten-year period of continued VGB use.
  
  
  METHODS
  From a group of 201 vigabatrin-exposed individuals with epilepsy, fourteen individuals were identified who were currently taking vigabatrin. All individuals had at least ten years exposure to vigabatrin. Individuals underwent several visual field examinations using Goldmann perimetry between Test 1 (first recorded examination) and Test 2 (most recent examination). All visual field results were analysed and quantified retrospectively by one investigator.
  
  
  RESULTS
  174 visual fields from the fourteen participants were available. The average follow-up period was 128 months. The prevalence of VAVFL increased from 64% at Test 1 to 93% at Test 2. The visual field size was significantly smaller at Test 2 compared to Test 1. All subjects showed a trend for decreasing visual field size with increasing cumulative vigabatrin exposure, when all fields for an individual were taken into account. There was a high degree of variability in visual field size between successive test sessions.
  
  
  CONCLUSIONS
  VAVFL progresses with continued vigabatrin exposure over a ten-year period. Progression may be slow and difficult to detect because of the high degree of variability in visual field size between successive test sessions. New techniques are needed to monitor the effects of vigabatrin retinotoxicity in people who continue vigabatrin therapy.
authors.affiliation: Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK. l.clayton@doctors.org.uk
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Clayton
authors.forename: William M
authors.initials: WM
authors.lastname: Stern
authors.forename: William D
authors.initials: WD
authors.lastname: Newman
authors.forename: Josemir W
authors.initials: JW
authors.lastname: Sander
authors.forename: James
authors.initials: J
authors.lastname: Acheson
authors.forename: Sanjay M
authors.initials: SM
authors.lastname: Sisodiya
mesh_terms: D000328:Adult; D000927:Anticonvulsants / Q000009:adverse effects*; D018450:Disease Progression; D004827:Epilepsy / Q000188:drug therapy; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010468:Perceptual Disorders / Q000139:chemically induced*; D020888:Vigabatrin / Q000009:adverse effects*; D058609:Visual Field Tests; D014794:Visual Fields / Q000187:drug effects*
chemical_list: D000927:Anticonvulsants; D020888:Vigabatrin
keywords: Goldmann perimetry; Optical coherence tomography; Vigabatrin; Visual field loss