title: Electroretinographic (ERG) responses in pediatric patients using vigabatrin.
abstract: The antiepileptic drug vigabatrin is known to cause retinal and visual dysfunction, particularly visual field defects, in some patients. Electroretinography (ERG) is used in an attempt to identify adverse effects of vigabatrin (VGB) in patients who are not candidates for conventional perimetry. We report data from 114 pediatric patients taking VGB referred for clinical evaluation; median age at test was 22.9 (2.4 to 266.1) months, and median duration of VGB use was 9.7 (0.3 to 140.7) months. Twenty-seven of them were tested longitudinally (3 to 12 ERG tests). ERG responses to full-field stimuli were recorded in scotopic and photopic conditions, and results were compared to responses from healthy control subjects. We found that abnormalities of photoreceptor and post-receptor ERG responses are frequent in these young patients. The most frequently abnormal scotopic parameter was post-receptor sensitivity, log σ, derived from the b-wave stimulus-response function; the most frequently abnormal photopic parameter was the implicit time of the OFF response (d-wave) to a long (150 ms) flash. Abnormal 30-Hz flicker response amplitude, previously reported to be a predictor of visual field loss, occurred infrequently. For the group as a whole, none of the ERG parameters changed significantly with increasing duration of VGB use. Four of the 27 patients tested longitudinally showed systematic worsening of log σ with duration of VGB use. In a subset of patients who underwent perimetry (N = 39), there was no significant association of any ERG parameter with visual field defects. We cannot determine whether the ERG abnormalities we found were due solely to the effects of VGB. We caution against over-reliance on the ERG to monitor pediatric patients for VGB toxicity and recommend further development of a reliable test of peripheral vision to supplant ERG testing.
authors.affiliation: Department of Ophthalmology, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA. anne.moskowitz@childrens.harvard.edu
authors.forename: Anne
authors.initials: A
authors.lastname: Moskowitz
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Hansen
authors.forename: Susan E
authors.initials: SE
authors.lastname: Eklund
authors.forename: Anne B
authors.initials: AB
authors.lastname: Fulton
mesh_terms: D000293:Adolescent; D000328:Adult; D000927:Anticonvulsants / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D004596:Electroretinography / Q000187:drug effects*; D006801:Humans; D007223:Infant; D008875:Middle Aged; D009422:Nervous System Diseases / Q000188:drug therapy; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D012164:Retinal Diseases / Q000139:chemically induced* / Q000503:physiopathology; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D020888:Vigabatrin / Q000009:adverse effects*; D014792:Visual Acuity / Q000187:drug effects; D014794:Visual Fields / Q000187:drug effects; D055815:Young Adult
chemical_list: D000927:Anticonvulsants; D020888:Vigabatrin