Stimulation of the retina of the eye with light causes changes in the electrical activity of the cerebral cortex. These changes can be measured from outside the skull and can give valuable information about the state of the visual pathway from the retinal ganglion cells to the occipital cortex. Not only can it determine that function is normal, it can also help to diagnose some causes of poor vision.
A reaction produced in response to visual stimuli. While the patient is watching a pattern projected on a screen, the electroencephalogram is recorded. The characteristics of the wave form, its latency, and the amplitude of the wave can be compared with the normal, and important information concerning the function of the visual apparatus in transmitting stimuli to the brain can be obtained.