Electrophysiology Testing in Patients with Inherited Retinal Disease

Electrophysiological testing allows objective assessment of retinal function. By changing the nature of the stimulus presented to the patient and the adaptive state of the eye (light or dark adapted) responses from different retinal cell types and layers can be obtained. The primary tests used in the evaluation of inherited retinal disease are the full-field electroretinogram (ERG), the pattern electroretinogram (PERG) and the electrooculogram (EOG), obtained following the International Standards for Clinical Electrophysiology in Vision (ISCEV) as well as the more recent techniques multi-focal electroretinogram (mfERG), ON/OFF ERG and s-cone ERG. Electrophysiological testing is useful for both the diagnosis and follow-up of patients with inherited retinal disease and is indicated when (1) the retina is morphologically “normal” but the patient is symptomatic, (2) the fundal appearance may not reflect the severity or nature of the disorder; (3) an accurate diagnosis is required or (4) prognostic information is required for the management of the patient. This chapter provides the basics of the electrophysiological techniques that can be used, suggests the pertinent tests to make the diagnosis and reviews the typical electrophysiological findings in a range of the more commonly encountered inherited retinal diseases.

Keywords: Electrophysiology, electroretinogram, pattern electroretinogram, electro-oculogram, visual evoked potentials, ERG, PERG, EOG, VEP, International Standards for Clinical Electrophysiology in Vision, ISCEV, onresponse, off-response, retina, optic nerve, eye, macula, retinal pigment epithelium, RPE, photoreceptor cell, bipolar cell, amacrine cell, gangion cell layer, horizontal cell, electrodiagnostics, a-wave, b-wave, P50, N95, dark adaptation, cone, rod, s-cone, Arden index, multifocal ERG, photopic, scotopic, inherited retinal disease, retinitis pigmentosa, RP, cone-rod dystrophy, cone dystrophy, pattern dystrophy, PD, adult vitrelliform macular dystrophy, AVMD, Best disease, Stargardt disease, fundus flavimaculatus, x-linked retinoschisis, retinoschisis, Leber congenital amaurosis, LCA, maternally inherited diabetes and deafness, MIDD, choroideremia, ESCS, Enhanced Scone syndrome, Congenital stationary night blindness, CSNB, carrier, fundus albipunctatus, Oguchi disease, Batten disease, macular dystrophy, Bull’s eye.