Local macular ERG in patients with Best's disease

We examined a pair of siblings, a 10-year-old girl (case 1) and a 12-year-old girl (case 2), with Best's disease. The visual acuity was nearly normal in both patients. The central visual field measured with auto-plot tangent screen revealed a small relative paracentral scotoma only in the left eye of case 2. We failed to detect any abnormality in photopic and scotopic electroretinogram (ERG) recorded with Ganzfeld stimuli and the electrooculogram light rise was absent in both patients. Local macular ERG was recorded under a fundus monitor by infrared television fundus camera with test spots of 5, 10, and 15 degrees in diameter. The center of the stimulus spot was always on the fovea during the recording. The local macular ERG was absent in both patients. Our results of local macular ERG may indicate disturbance of the central portion of the retina.