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Sometimes a person experiences a sudden loss of vision even though his or her eyes appear perfectly normal. When this happens, the problem could be in the retina or the nerve link between the eyes and the brain. Electrophysiology lets physicians find out what’s happening.
In this test, the patient wears a contact lens with an embedded electrode (the eye is numbed with an anesthetic drop to reduce discomfort). Another electrode may be placed on the back of the head. While the patient watches lights on a screen, the test apparatus measures electrical impulses.
Electrophysiology is useful not only for exploring sudden vision loss, but for evaluating patients who are unable to communicate what they see. To get useful readings, the patient must first become completely dark-adapted by sitting in the dark for a long period. For this reason, the test takes about two hours.
Author: Dale K. Heuer, MD Date: Sept. 14, 2004 |