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Medical Author:

John Sheppard, MD

Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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In this Article

• What is electroretinography?
• How is an ERG done?
• What do the electrodes do?
• How are eletroretinography readings made?
• Why is an ERG done?
• What diseases is my doctor looking for with an ERG?
• What is a multifocal ERG?
• What is a normal outcome for an ERG?
• What does an abnormal ERG mean?
• Does the test hurt?
• What are the risks of an ERG?
• How long does the ERG take?
• How about after the test?
• How much does an ERG cost?
• Find a local Eye Doctor in your town
• Electroretinography Index

What does an abnormal ERG mean?

An abnormal ERG result suggests abnormal function of the retina due to diseases of the retina or abnormal function of the retina as occurs with other conditions such as arteriosclerosis (hardening of the arteries) involving the eye vessels, giant cell arteritis with eye involvement, metabolic diseases called mucopolysaccharidoses, detachment of the retina, siderosis (excess iron deposits), and vitamin A deficiency.

Does the test hurt?

The test is painless. However, the electrode that rests on the eye may feel a little like an eyelash has lodged in the eye. This sensation may persist up to several hours following completion of the ERG.

What are the risks of an ERG?

There are no risks specifically associated with an ERG. Some patients experience mild ocular discomfort during or after the procedure. Rarely, a corneal abrasion may occur, which is readily treated with early detection. If you believe you have irritation or a corneal abrasion following an ERG, you should call your eye doctor or the doctor who ordered your ERG.

How long does the ERG take?

The ERG takes about an hour or less.

How about after the test?

One should not rub the eyes for an hour after an ERG (or any test in which the cornea has been anesthetized), lest one injure the cornea.

How much does an ERG cost?

Generally speaking, an ERG will be billed by your doctor or your hospital back to your insurance company. The same vagaries that haunt the billing process for most complex cases can undoubtedly affect collections for ERG. Any claim can lead to some reimbursement rejections by insurance or difficulties for patients tasked with handling their own billing matters. The cost for an ERG performed on a Medicare patient is about $150. Medicaid reimbursement may be lower.