The retina is the tissue in the back of the eye that receives the visual input and sends it to the visual center within the brain. A retinal exam is part of every visit. There are certain conditions that require a more specific test to determine how well it is functioning. The patient is connected to a computer and electrodes are placed around the head and eyes. The retinal function is measured in microvolts of electrical activity. This test is commonly performed on patients with cataracts or certain retinal/optic nerve disorders.