A retinal migraine starts at the back of the eye or the retina. Our retinas translate light to the brain with an electrical signal that will then arrange an image for us. One theory for the cause of a retinal migraine is that there is a temporary reduction of blood flow to the area of the retina, and this will cause blurry vision or a blind spot that can get bigger as the migraine goes on. This occurs in only one eye. This reduction of blood flow may induce a twinkling of light or a temporary loss of vision. A retinal migraine can last anywhere from five minutes to an hour, after that vision will go back to normal.
There is also a migraine aura; these start in the brain and both eyes are affected. Before a headache comes, people will see an aura that shows in both eyes. These can also happen without a headache. Symptoms with a migraine aura are having foggy vision, wavy or “watery” vision, blind spots, bright spots, flashing light, or zigzagging lines. Flashing lights or bright spots can still be seen when the eyes are closed. A major difference with the migraine aura and ocular migraine is that the aura will move across the field of view and take up to half an hour to go away. With this kind of migraine, people will feel pain or pressure behind the eyes and experience sensitivity to light.
There are a number of things that cause migraine auras including: Stress, dehydration, smoking, caffeine and withdrawal, eye strain, bright lights, hormonal changes, contraceptive medication, food and chemical sensitivity, and high or low blood pressure.