A wave in ERG is due to the activity of: (A) Pigmented epithelium, (B) Rods and cones, (C) Ganglion cell, (D) Bipolar cell
Answer is B. Normal record of ERG consists of the following waves : a-wave. It is a negative wave possibly arising from the rods and cones. b-wave. It is a large positive wave which is generated by Muller cells but represents the activity of the bipolar cells. c-wave. It is also a positive wave representing the metabolic activity of pigment epithelium. Both scotopic and photopic responses can be elicited in ERG. Foveal ERG can provide information about the macula. REFERENCE : AK KHURANA COMPREHENSIVE OPHTHALMOLOGY, Edition4,Page-489