ERG stands for electroretinogram. This records the electrical activity from the nerves in the eye.
About your ERG?
Although it is not painful, some parts of the test can be irritating or slightly uncomfortable. Sometimes eye drops may be needed, which can cause blurred vision for a few hours, so you should not drive after the test. Hair should be clean and dry. Please do not use any hair products for example gel, hairspray
Preparation for the test
- There are no special preparations needed before this test.You can eat and drink and continue to take any medication as normal.
- Bring a list of current medications.
- If you wear glasses, please bring them with you. Avoid wearing contact lenses.
How is it done?
Some electrodes will be attached to your head. The skin beneath the electrodes is rubbed with a cotton bud and the electrodes are attached using a sticky paste. Some minor skin irritation may occur. Please make staff aware if you have a skin complaint or allergy.
Some electrodes need to go near the eye. Two types of electrodes are available. One sits close to the eye, this means it can be slightly uncomfortable, but not painful.
The other is a sticker which sticks to the cheek below the eye. The physiologist performing the test will discuss both options with you and will decide which is most appropriate for you. You will then be asked to watch either a pattern on a TV screen or flashing lights. This will be performed in both light and dark conditions. Once the recording is finished, the electrodes and paste are removed.
What is a VER (Visual evoked response)?
A visual evoked response is a recording to check the nerve pathway from your eyes to your brain. It is not painful and has no after-effects.
Preparation for the test
- You should eat and drink as normal prior to the test.
- Hair should be clean and dry. Please do not use any hairproducts for example gel, hairspray.
- Continue to take medications as prescribed.
- If you wear glasses, please bring them with you.
- Bring a list of current medications.
- The test can last up to one hour.
How is it done?
The test involves attaching electrodes to the head. The skin beneath the electrodes is rubbed with a cotton bud and the electrodes are applied using a sticky paste. Some minor skin irritation may occur. Please make staff aware if you have a skin complaint or allergy.
You will then be asked to watch a moving pattern, which will be shown on a monitor. Alternatively a flashing light may be used. A series of recordings on a computer will be made. The whole test lasts around 2 hours in total.
Once the recording is finished the electrodes and paste will be removed. You may wish to wash your hair when you get home. The test is performed by a physiologist.
Test results
All results will be analysed by a consultant who specialises in neurophysiology. The report will not be available immediately but should reach your GP/Consultant within 7-14 days
We welcome feedback about our services. Please tell a member of staff if you felt this service was good or otherwise.
Large print copies of this information are available on request from the department on the number below.
Contact Details
If you have any queries or questions regarding the information in this leaflet, please contact the Neurophysiology Department on:
