Pattern ERG (PERG) measures electrical activity from retinal ganglion cells in response to a reversing checkerboard pattern. It’s great for spotting optic nerve issues like glaucoma and macular problems.
- How it’s done: Electrodes on the eye, patient looks at a screen with a checkerboard pattern that flips contrast.
- What it records: P50 wave (early positive) reflects ganglion cell function; N95 wave (negative) relates to optic nerve health.
- Key use: Detects ganglion cell loss early, even before visual field defects show up.
- Difference from full-field ERG: PERG focuses on central retina and optic nerve, not whole retinal response.