Also called ophthalmic or eye migraines, ocular migraines are common and usually painless. They may cause various visual problems such as visual disturbances and the appearance of a small, enlarging blind spot in your central vision. Inside the spot, there are flicking lights or a shimmering zigzag line. During the process of ocular migraines, the spot enlarges and may move across your visual field. This process lasts from several minutes to 30 minutes.