PatternERG

PatternERG is a diagnostic electrophysiological technique used to assess retinal function by recording electrical responses to spatially structured visual stimuli, typically high-contrast patterns such as checkerboards or gratings.

In the test, a participant fixates on a patterned stimulus displayed on a monitor while the pattern periodically reverses or flickers at a predetermined rate. The retinal response is captured with corneal or skin electrodes and amplified; the waveform is analyzed for characteristic components, commonly a P50 followed by an N95 in humans. Pattern stimuli minimize rod-driven responses and emphasize inner retina function, especially retinal ganglion cells in the macula.

Interpretation: PatternERG amplitudes and latencies provide information about retinal ganglion cell and macular pathway integrity. Reduced amplitude or delayed latency can indicate dysfunction due to glaucoma, optic neuropathies, or macular disease, and can be used to monitor progression or treatment effects. PatternERG is often considered complementary to full-field ERG and to visual evoked potentials (VEP).

Procedure considerations and limitations: Accurate results require stable fixation, appropriate refractive correction, and adequate patient cooperation. Visual acuity and media clarity influence the ability to generate recognizable patterns; poor fixation or high refractive error can reduce signal. Equipment demands include a pattern generator (or video display with precise timing) and recording electronics.

History and scope: PatternERG has been used since the late 20th century as a tool for assessing inner retinal function. They are particularly valuable in glaucoma clinics and retinal research, and continue to evolve with advances in digital displays and signal processing.