Electroretinography (ERG) is a test that measures the electrical response of the retina’s light-sensitive cells (rods and cones) to light stimuli. It helps diagnose retinal diseases like retinitis pigmentosa, macular degeneration, and Leber congenital amaurosis.
- How it works: Electrodes placed on the cornea or skin around the eye record electrical activity while the eye is exposed to flashes of light.
- What it shows: Waves (a-waves, b-waves) reflecting function of photoreceptors and inner retinal layers.
- Types: Full-field ERG (tests whole retina), multifocal ERG (tests small areas), and pattern ERG (tests ganglion cells).
- Use: Detects retinal dysfunction even before vision loss is noticeable.