EVALUATING MACULAR FUNCTION USING THE FOCAL ERG

  • 1 July 1986
    • journal article
    • research article
    • Vol. 27  (7) , 1123-1130
Abstract
A stimulus consisting of 96 red LEDs mounted in the rear of a ganzfeld bowl was used to elicit focal electroretinograms (FERG) from the central 9.degree. of the retina in human subjects. The luminance of the stimulus was driven sinusoidally at frequencies from 10-60 Hz. The temporal responsiveness and response phase legs of normal subjects and patients with retinal disease were measured. Normal subjects produced maximum amplitude FERG responses to stimuli between 30-40 Hz. Patients with retinitis pigmentosa showed a low-pass pattern of amplitude loss, with an additional frequency independent loss in sensitivity in those with poorer visual acuity. Patients with macular degeneration showed general amplitude loss associated with a relative sparing of the mid-temporal frequencies. The response phase lags in both patient groups were not significantly different from the normals. These findings point to a loss in temporal responsiveness accompanied by a secondary loss of sensitivity in these heredoretinal degenerations.