ON–OFF electroretinogram analysis in patients with negative electroretinograms

Abstract

Aims/Purpose: In a healthy population, the flash full‐field electroretinography (ffERG) includes a negative a‐wave and a positive b‐wave. The amplitude of the b‐wave is larger than the a‐wave amplitude in normal patients. In dark‐adapted ERG, the b:a ratio is about 1.6–1.8. The term “negative electroretinogram” is used when the b‐wave amplitude is smaller (negative–negative) or relatively smaller (negative–positive) than the a‐wave amplitude.This study aims to describe the differences in the ERG of patients with a negative ERG caused by genetic and acquired diseases to help better narrowing down an accurate diagnosis.Methods: The retrospective study comprised 10 patients aged 5–43 years (4 female, 6 male). ffERG was done according to the ISCEV standards. ON–OFF ERG protocol was additionally used. RETeval portable device (LKC, USA) and sensor strip palpebral electrodes were used.Results: Negative ERG was found in patients with congenital stationary night blindness (X‐linked, autosomal dominant, autosomal recessive, Oguchi disease), fundus albipunctatus, X‐linked retinoschisis, vitamin A deficiency, vigabatrin toxicity, retinal inflammation. In ON–OFF protocol differences between the function of the ON and OFF bipolar cells in the various diseases are present and will be discussed.Conclusions: ffERG with ON–OFF protocol should be done in all patients with nyctalopia or inner retina diseases. Detailed analysis of ERG may help to establish the clinical diagnose of retinal disease and to narrow the area of genetic investigation.