"On" response dysfunction in multifocal posterior pigment epitheliopathy

ISCEV extended protocol for the photopic On-Off ERG

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.

Recording rod ON and OFF responses in ERG and multifocal ERG

The 5 Hz rectangle stimulus was generally used to record cone ON and OFF response. In this study, the feasibility and recording conditions of recording rod ON and OFF responses in electroretinograms (ERG) and multifocal electroretinograms (mf-ERG) were described, and the character and influence factors of these responses were observed. The result demonstrated that the rod ON and OFF responses of ERG can be recorded with sawtooth rapid-on and rapid-off stimulus. There is a small positive wave in downhill of negative wave in rod OFF response. Rod ON response of mf-ERG can be recorded with simulated rapid-on stimulus. We speculated that the simulated rapid-ON, sawtooth rapid-on and rapid-off stimulus can be an useful tool to investigate retinal disease and have certain clinical values.