Flashes and floaters are common conditions patients experience in their vision. The cavity of the eye is filled with a clear gel called vitreous humor, or simply vitreous. It provides structural support for the eye and allows light to pass through it and focus on the retina. The vitreous is attached to the retina. Over time or with trauma, this attachment can loosen. When this occurs, the retina is pulled by the retraction of the vitreous. This strain causes the retina to produce an impulse that the brain interprets as a flash of light. Since the retina has no pain fibers, this is the only way it can signal tension on itself. If the tension is strong enough, the vitreous adhesion can detach from the retina. This is called a posterior vitreous detachment, or PVD. Microscopic cells can be released into the vitreous cavity in this event, which leads to "floaters."
As long as the retina is not injured, both of these events are harmless, although patients will complain of visual disturbances. Commonly, they will report seeing specks floating in their view, which move when the eye moves. Although these floaters do not go away, the brain learns to ignore these small disturbances, and most report in a few weeks that they do not see or only occasionally see the floaters. The flashes resolve once the vitreous completely separates from part or all of the retina.
Your eye doctor will recommend several checks throughout a six week period to ensure that the retina has not been disturbed or injured during this process. Some highly nearsighted patients are prone to spontaneous PVDs, so regular annual checks are recommended for those with high prescription glasses or contacts.