Electroretinogram traces showing flicker response and cone response. The subject is a child who began vigabatrin at 5 months of age and had electroretinogram testing at approximately 6-month intervals during vigabatrin treatment and after vigabatrin treatment (labeled age off). The last waveform (gray electroretinogram trace) is data recorded from a 30-month-old control (with normal vision). Adapted from: Westall CA, Nobile R, Morong S, Buncic JR, Logan WJ, Panton CM. Changes in the electroretinogram resulting from discontinuation of vigabatrin in children. Doc Ophthalmol. 2003;107:299–309.