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- What is electroretinography (ERG)?
- How is an ERG done?
- What do the electrodes do?
- How are electroretinography 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 ERG test hurt?
- What are the risks of an ERG test?
- How long does the ERG test take?
- How about after the ERG test?
- How much does an ERG test cost?
What diseases is my doctor looking for with an ERG?
There are a number of conditions, mostly ocular in nature, in which the ERG may provide useful information. The diagnoses most commonly suspected when ordering an ERG are predominantly conditions of the retina, including:
- retinitis pigmentosa,
- retinitis punctata albescens,
- retinitis pigmentosa sine pigmento,
- related hereditary retinal degenerations,
- disorders that mimic retinitis pigmentosa,
- Leber's congenital amaurosis,
- gyrate atrophy of the choroid,
- gyrate atrophy of the retina,
- Goldman-Favre syndrome,
- congenital stationary night blindness,
- X-linked juvenile retinoschisis,
- cone dystrophies, and
- Usher syndrome.
What is a multifocal ERG?
The multifocal ERG focuses on different areas of the retina, looking for localized areas of abnormality. This tests takes longer than a simple ERG.
What is a normal outcome for an ERG?
A normal ERG shows a normal A- and B-wave pattern with appropriate increases in electrical activity with increased light intensities.
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.