<prompt> All of them are true about ERG exceptMeasures the potential difference of the neurosensory layer of retinaThe negative A wave is produced by the hyperpolarization of the photoreceptorsThe positive B wave is due to the bipolar and Mullers cellsFlash ERG is a good for detection of macular diseases  <response>: Electroretinography ERG is the record of changes in the resting potential of the eye induced by a flash of light. Components of normal electroretinogram ERG a-wave. It is a negative wave possibly arising from the rods and cones photoreceptors. b-wave. It is a large positive wave which is generated by Mullers cells, but represents the activity of the bipolar cells . c-wave. It is also a positive wave representing metabolic activity of pigment epithelium seen only in dark adapted eye. A flash ERG requires a large area of retina to be abnormal for being detectable and thus in macular disorder where only small pa of retina is involved , flash erg doesnt detect it 