THE ERG c‐WAVE IN VITELLIRUPTIVE MACULAR DEGENERATION (VMD)

Abstract

D.c. ERG registrations and EOG recordings were obtained from six patients with vitelliruptive macular degeneration (VMD). In all cases the EOG was highly pathological, but the alpha- and beta-waves of the ERG were normal. This is typical of VMD, which starts as a generalized defect of the pigment epithelium. Four patients showed no evidence of a c-wave. The other patients demonstrated small c-waves, but only under certain stimulus conditions. Thus, varying stimulus durations, intensities and frequencies are sometimes needed to decide whether or not ERG c-waves can be elicited in different diseases or suspected disorders. The findings are in agreement with the presence of a generalized pigment epithelial defect in VMD, since the major positive component of the c-wave is generated by the pigment epithelium-receptor complex.

Electrophysiology in pigment epithelial changes

“…Amplitude calibration 100 pV. be detected when low stimulus intensities were used or at the time of the SP light peak when repeated recordings were performed), which is in accordance with the general pigment epithelial abnormality (Nilsson & Skoog 1980).…”

“…However, clearly the major component .of the c-wave originates in the pigment epithelium. A d.c. ERG technique has been developed also for clinical work to study the reactions and the state of health of the retina and pigment epithelium (Nilsson & Knave 1974; Nilsson & Skoog 1975;Skoog et al 1977;Textonus 1978;Nilsson 1980;Nilsson & Skoog 1980). The resting potential of the eye or the standing potential (SP), upon which the ERG is superimposed, is generated across the apical surface of the pigment epithelium.…”

Inherited Macular Dystrophies and Differential Diagnostics

“…Protanopia may be seen. The findings on standard ERG are normal; however, it shows a dramatically reduced or disappeared c-wave, which basically reflects the function of pigment epithelium (22). The essential test the EOG, which does not record photopic rise, and Arden index approximately remains as 1.0.…”