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An electroretinogram (ERG) is a specialized diagnostic test that measures the electrical responses of the light-sensitive cells (photoreceptors) and other cells in the retina. It is used to diagnose various hereditary and acquired retinal disorders.
read more about electroretinogram ...The primary function of the test is to assess retinal function. The test measures the electrical potential generated by the retina in response to flashes of light. This electrical response indicates the health and activity level of the rods (night vision) and cones (day and color vision) across the retina. The waveform produced provides a precise profile of cellular health.
The procedure works by placing a small electrode (usually in the form of a soft contact lens) on the surface of the eye. The patient looks into a machine that delivers controlled light flashes (varying in color and intensity) while the electrode records the retina's electrical response. The procedure is painless, as the eye is numbed with anesthetic drops. Both dark and light adaptation is necessary to test rods and cones separately.
The Electroretinogram is a powerful tool for diagnosing specific retinal diseases. It is needed for diagnosing hereditary conditions like retinitis pigmentosa (progressive rod-cone degeneration) and cone dystrophies. It is also used to assess toxic damage from certain medications.
Dark adaptation is necessary to isolate the function of the rod photoreceptors (cells responsible for night vision). The patient sits in complete darkness for 20 to 30 minutes before testing, which allows the rods to become highly sensitive for accurate measurement.
The role of the contact lens is to serve as the main electrode. The soft lens material is used because it provides comfortable and stable contact with the cornea to pick up the very small electrical signals generated by the retina without damaging the eye's surface.
No, the eye is numbed with drops, and the contact lens electrode is soft, making the procedure painless.
No, the ERG is a specialized test reserved for patients with suspected retinal degeneration or inherited diseases.
Yes, because the eyes are dilated for the test, vision will be temporarily sensitive to light and blurry for several hours.
Consult a retinal specialist if you have "Night Blindness" (Nyctalopia) or unexplained peripheral vision loss. An ERG measures the electrical response of your rods and cones. It is a critical medical tool for diagnosing diseases like Retinitis Pigmentosa or toxicity from certain high-risk medications.
AAO. Electroretinography (ERG) (aao.org). 2024.
Cleveland Clinic. ERG Testing (clevelandclinic.org). 2024.
StatPearls. Clinical Electroretinogram (ncbi.nlm.nih.gov). 2024.
National Eye Institute. Retinal Diseases (nei.nih.gov). 2024.