Pattern-reversal visual-evoked potential in patients with occult macular dystrophy

PURPOSE Occult macular dystrophy (OMD) is a hereditary retinal disease characterized by a normal fundus, normal full-field electroretinograms (ERGs), progressive decrease of visual acuity, and abnormal focal macular ERGs. The purpose of this study was to report pattern-reversal visual-evoked potential (pVEPs) findings in OMD patients. PATIENTS AND METHOD The pVEPs recorded from four patients with OMD (aged 42-61 years; 2 men and 2 women) were reviewed. The visual acuities ranged from 20/200 to 20/30. The amplitudes of the N-75 and P-100 (P2 amplitude) and the latency of the N-75 components (N1 latency) were analyzed. RESULTS The mean (±SD) P2 amplitude was 2.7 ± 1.9 μV for the 5', 4.8 ± 2.9 μV for the 10', 3.2 ± 2.1 μV for the 20', and 4.4 ± 3.5 μV for the 40' checkerboard stimuli. The N1 latency was 122.2 ± 6.4 ms for the 5', 105.0 ± 11.5 ms for the 10', 97.7 ± 10.0 ms for the 20', and 91.0 ± 13.7 ms for the 40' checkerboard stimuli. The mean P2 amplitude was reduced and the N1 latency was delayed in comparison with the laboratory standard for the Keio University Hospital. CONCLUSIONS The delayed latency and reduced amplitude suggest a major contribution of the central cone pathway to the pVEPs.