Inhibitory effect of central vision on occipital lobe seizures.

We studied four young patients with occipital lobe seizures (elementary visual hallucinations, blindness, and tonic deviation of the eyes) and electroencephalographic (EEG) abnormalities of occipital spike and slow-wave activity, which occurred continuously as long as the eyes were closed. The EEG abnormalities were inhibited by opened eyes in an illuminated room and returned immediately in darkness. Opening and closing the eyes in darkness did not alter the continuously occurring spike and slow-wave activity. The retention of central vision in darkness, caused by looking at a red spot of light, inhibited these abnormalities. Therefore, some occipital lobe seizures may not be "spontaneous" but may be elicited by "loss" of central vision, particularly when they occur in darkness or sleep.