22 June 2018
Clinical standards, Electroretinogram (ERG), Full-field ERG, International Society of Clinical Electrophysiology of Vision (ISCEV), On–Off ERG, Long-duration ERG, Bipolar cells, Retinopathy, Retinal dystrophy
The International Society for Clinical Electrophysiology of Vision (ISCEV) standard for full-field electroretinography (ERG) describes a minimum procedure, but encourages more extensive testing. This ISCEV extended protocol describes an extension to the ERG standard, namely the photopic On–Off ERG, and outlines common clinical applications. A light stimulus duration of 150–200 ms is used in the presence of a rod-suppressing background to elicit cone-driven On- and Off-system ERG components. The On-response occurs after the stimulus onset and has a negative a-wave and positive b-wave. The Off d-wave is a positive component evoked by stimulus offset. Common diagnoses that may benefit from additional photopic On–Off ERG testing include retinal dystrophies and retinal disorders that cause dysfunction at a level that is post-phototransduction or post-receptoral. On–Off ERGs assess the relative involvement of On- and Off-systems and may be of use in the diagnosis of disorders such as complete and incomplete congenital stationary night blindness (complete and incomplete CSNB), melanoma-associated retinopathy, and some forms of autoimmune retinopathy. The photopic On–Off ERGs may also be useful in X-linked retinoschisis, Batten disease, Duchenne muscular dystrophy, spinocerebellar degeneration, quinine toxicity, and other retinal disorders.