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Pattern Electro-retinography (PERG)

What is a Pattern Electro-retinogram (PERG)?

This is a test of the electrical activity from the eye.  It is used to determine how healthy particular cells are in the retina.  It is often performed in conjunction with an Electro-retinogram (ERG).

If you wear glasses please bring them with you.

How is it performed?

To do this a very fine thread is placed between the lower eyelid and the eyeball.  The thread is placed quickly and you may feel a little discomfort for a few seconds but this will not last.   Leads will also be placed on your face at the side of your eyes and one lead on your forehead.   You will then be asked to concentrate on a reversing chequerboard pattern for 2-3 minutes.  This test is then repeated.   

How do I prepare for the test?

If you are taking medication please continue to take it and bring a list of your medication with you.

Continue to eat meals as normal.

If you suffer from epilepsy you should let the Clinical Physiologist know at the start of your test.

How long will I have to wait?

You have been given a specific appointment time and patients are usually seen on time.  It is important that you arrive on time.  Please allow plenty of time for parking.

This test takes up to 30 minutes to complete.

When will I get the results?

The results are sent to the doctor that referred you for the test and are usually available within seven days.


Neurophysiology Department   01422 222976

If you have any concerns or questions please speak to one of the Clinical Physiologists on the above number.