Peripheral eye flashes, or floaters, are shadows on the retina caused by microscopic fibers in the vitreous. Floaters are usually harmless but may indicate retinal detachment, which can lead to blindness, states the National Eye Institute.
Jelly-like vitreous, which fills most of the eye and helps maintain its round shape, shrinks with age and becomes stringy, according to the National Eye Institute. These strings cast tiny shadows on the retina, appearing as dots, strings or cobwebs that seem to move when looked at directly. They are more apparent when looking at bright objects such as the sky. Many people see floaters, and while these floaters are annoying, they require no treatment.
A sudden increase in floaters, especially if accompanied by flashing lights or loss of peripheral vision, requires immediate medical attention, explains Mayo Clinic. These symptoms could indicate a tear in the retina, which can lead to blindness if not treated promptly. The retina is the light-sensitive tissue on the back wall of the eye.
Sometimes floaters are so dense and numerous they can affect vision. Options for treatment include laser therapy to break up floaters in the vitreous, such as a vitrectomy, which is surgery to remove the vitreous and replace it with a saline solution. Both treatments have significant risks, notes the National Eye Institute.