An ocular migraine occurs when blood vessels in the part of the brain responsible for vision temporarily spasm. Ocular migraines cause a disturbance in one's vision, known as an aura, which typically lasts from several minutes to about an hour. An aura may appear as a blank spot, flickering colored lights, zig-zag lines, or a blurred area of vision like looking through heat waves. After the episode of visual distortion is over, a person may feel complete back to normal. If this is the case, no treatment is needed, even if a person experiences multiple episodes over time. Other people may experience a kind of altered sense of awareness after an episode. Lights or sounds may be unusually intense. They may feel a little nauseous, and may also have a headache. If a person experiences any of these other symptoms, their ocular migraine may be progressing into a classic migraine, and they should be referred to their medical doctor for treatment.