title: Attenuation of the retinal nerve fibre layer and reduced retinal function assessed by optical coherence tomography and full-field electroretinography in patients exposed to vigabatrin medication.
abstract: OBJECTIVE
  To investigate the clinical value of assessment of peripapillary retinal nerve fibre layer (RNFL) thickness with OCT in addition to the evaluation of retinal function measured by full-field electroretinography (ff-ERG) in patients with suspected vigabatrin (VGB)-attributed visual field defects.
  
  
  METHODS
  Visual fields from adult patients in our clinical follow-up program for VGB medication were analysed. Twelve patients with suspected VGB-attributed visual field defects were selected for the study. They were re-examined with computerized kinetic perimetry, ff-ERG and OCT (2D circle scan).
  
  
  RESULTS
  Constricted visual fields were found in all patients. Comparative analysis of ff-ERG parameters showed reduced b-wave amplitudes for the isolated and the combined rod and cone responses (p < 0.0001). The a-wave, reflecting photoreceptor activity, was reduced (p = 0.001), as well as the summed amplitude of oscillatory potentials (p = 0.029), corresponding to inner retinal function. OCT measurements demonstrated attenuation of the RNFL in nine of 12 patients, most frequently superiorly and/or inferiorly. No temporal attenuation was found. Significant positive correlations were found between the total averaged RNFL thickness, superior and inferior RNFL thickness and reduced ff-ERG parameters. Positive correlations were also found between RNFL thickness and isopter areas.
  
  
  CONCLUSIONS
  OCT measurements can detect attenuation of the RNFL in patients exposed to VGB medication. RNFL thickness correlates with reduced ff-ERG parameters and isopter areas of constricted visual fields, indicating that VGB is retino-toxic on several levels, from photoreceptors to ganglion cells. The study also supports previous studies, suggesting that OCT measurement of the RNFL thickness may be of clinical value in monitoring patients on vigabatrin therapy.
authors: Department of Ophthalmology, University of Lund, Lund, Sweden.
authors: Ulrika
authors: U
authors: Kjellström
authors: Sten
authors: S
authors: Andréasson
authors: Vesna
authors: V
authors: Ponjavic
mesh_terms: D000328:Adult; D000368:Aged; D000927:Anticonvulsants / Q000009:adverse effects*; D004596:Electroretinography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000187:drug effects / Q000473:pathology*; D009898:Optic Disk / Q000187:drug effects / Q000473:pathology; D012029:Refraction, Ocular; D012160:Retina / Q000187:drug effects / Q000503:physiopathology*; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000473:pathology*; D041623:Tomography, Optical Coherence; D020888:Vigabatrin / Q000009:adverse effects*; D014786:Vision Disorders / Q000139:chemically induced; D014792:Visual Acuity; D058609:Visual Field Tests; D014794:Visual Fields / Q000187:drug effects
chemical_list: D000927:Anticonvulsants; D020888:Vigabatrin
keywords: anti-epileptic drug; drug toxicity; full-field electroretinography; optical coherence tomography; vigabatrin; visual field defect