The c-wave of the electroretinogram in vitelliruptive macular degeneration (älvdalssjukan).

The d.c. ERG and the EOG were recorded from 6 patients with vitelliruptive macular degeneration (VMD, Alvdalssjukan). All EOGs were highly pathological. The a- and b-waves of the ERG were normal. These are pathognomonic findings in VMD, which starts as a generalized disturbance of the pigment epithelium. No signs of a c-wave were seen in 4 patients. Small c-waves occurred in 2 patients, but only under certain stimulus conditions. The major positive component of the c-wave is produced by the pigment epithelium -- receptor complex. Absent or pathological c-waves in VMD, a pigment epithelial disease, are in good agreement with what is known about the origin of the c-wave.