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.