To accurately understand some eye diseases, special diagnostic tests are needed to show how the eye and optic nerve communicate with the brain. ERG, EOG, VER and VEP tests are the four basic electrophysiological tests used for this purpose.
What is ERG Test (Electroretinography)?
It is a diagnostic method that measures the electrical response of retina cells to light. It is considered a retinal function test. The pupil is dilated with drops, a special contact electrode is placed and light stimuli of different intensities are given to the patient. It is preferred in retinitis pigmentosa, diabetic retina disease and hereditary retina diseases. The procedure takes approximately 15-20 minutes and is painless.
What is EOG Test (Electrooculography)?
It measures the electrical potential difference between the retinal pigment epithelium and the eye muscles. It is applied in hereditary retinal diseases such as difficulty in night vision, sensitivity to light, Best's disease or retinitis pigmentosa. Electrodes are placed around the eyes and the electrical changes of the eye looking left and right are recorded.
What is VEP Test (Visual Evoked Potential)?
It measures whether the signals coming out of the eye are perceived by the brain. It shows whether the conduction path between the optic nerve and the brain is working properly. It is used for suspicion of optic neuritis, to understand whether vision loss originates from the eye or the brain, and in the diagnosis and follow-up of neurological diseases such as MS (Multiple Sclerosis). Small electrodes are placed on the head area and the patient looks at black-and-white patterns on the screen.
Who Are These Tests Suitable For?
- Those with unexplained vision loss
- Patients with suspected optic nerve diseases
- Those with suspected hereditary retinal disease
- Those who are being monitored for neurological diseases (MS, etc.)
- Patients whose visual development is monitored in children
Frequently Asked Questions
Is the ERG test painful?
No. The procedure is painless. Placing a contact electrode on the eye may cause mild discomfort in some patients, but no pain is felt.
Why does the VEP test look like a brain test?
Because the VEP test measures whether the visual signals coming from the eyes are received by the brain. It tests the communication between the optic nerve and the brain's visual center.
Is there any special preparation required for these tests?
In the ERG test, the pupil is dilated with drops. No special preparation is required for other tests. After all the tests, you can return to daily life immediately.
