Warning signs of an ocular migraine include: Vision problems that affect one eye, such as flashing lights, blind spots in your field of vision, or blindness. You might have them for only a few minutes or up to 30 minutes. These problems affect just one eye, which makes ocular migraines different from other types. It can be hard to tell the difference between flashing lights or blindness in one side of your vision -- but involving both eyes -- and having these symptoms in only one eye. If you can’t tell, cover one eye and then the other.