MACULAR ELECTRORETINOGRAMS: THEIR ACCURACY, SPECIFICITY AND IMPLEMENTATION FOR CLINICAL USE

Open Access
Publisher Website
Google Scholar
Abstract
The pattern and the focal electroretinogram (ERG) are both non-invasive, electrophysiological responses recorded from circumscribed retinal areas and are most easily recorded from the macula. This paper describes how the department has incorporated these tests into clinical protocol, shows how the recording technique and the method of electrode construction may be improved, and describes the normal limits of the macular responses obtained. The ERG signal-noise ratio obtained was better than that of the binocular visual evoked potentials (VEP) recorded simultaneously. Pattern and focal ERG, using improved methods of recording, show promise of being a valuable addition to the clinical investigation of subtle maculopathies and some forms of optic nerve dysfunction. Three illustrative cases are described. The 1st demonstrates normal macular ERG responses with abnormal Ganzfeld ERG due to peripheral retinal damage. The 2nd reveals differential pattern ERG reduction with normal focal ERG in recent optic neuritis. The 3rd case demonstrates reversible simultaneous loss of Ganzfeld ERG and macular ERG in vitamin A deficiency.