What does it mean to see flashing lights and squiggly lines?

Needs evaluation: This if in one eye only is usually due to disturbance of the fluids of the back of the eye or the retina. Since it can be serious, you should be evaluated for this occurrence - especially if persistent. Occipital migraines can also create this visual disturbance but will disappear in several minutes to several hours, and occurs in both eyes at the same time.

See a retina special: New or worse floaters in your vision or flashing lights or loss of peripheral vision (like a curtain or veil obstructing the vision) could indicate a retinal detachment. These symptoms require an urgent dilated retinal exam. Do not delay. Your symptoms may also be due to a posterior vitreous detachment.