Electrophysiological findings in dominant optic atrophy (DOA) linking to the OPA1 locus on chromosome 3q 28-qter

Pattern and flash visual evoked cortical potentials (PVEP, FVEP), and pattern electroretinograms, (PERG) were recorded in 13 affected individuals from 8 families with DOA. These were selected as representative from 87 affected members of 21 pedigrees with DOA who were examined, and who underwent genetic linkage analysis. Linkage to the OPA1 locus on chromosome 3q 28-qter was demonstrated in all families. VA ranged from 6/9 to HM; visual fields showed a variable centro-caecal defect; SLO (when performed) showed diffuse nerve fibre loss; MRI (when performed) showed small intra-orbital optic nerves. In 9/13 patients the PVEP was absent in one or both eyes. Most recordable PVEPs were of abnormal latency, but the delays were not marked (peak times 116-135 msec); amplitudes were low or subnormal. PERG fell within the normal range in 9 eyes of 7 patients. 14 eyes showed an abnormal N95:P50 ratio in keeping with ganglion cell dysfunction. Some severely affected eyes showed P50 co mponent involvement, but in no eye was the PERG extinguished. Significant interocular asymmetries in at least one electrophysiological measure were present in 6/13 patients. Colour contrast thresholds were significantly elevated for all three colour confusion axes, with tritan being most affected.