Flashes are experienced as a lighting streak, originating within the eye. Flashes are most often noticed at night or in a dark room. Floaters are perceived as freely mobile single or multiple black spots, or irregular shapes in the field of vision. Floaters are usually seen during daylight or in lightened areas.
The interior portion of the eye is filled with a substance called vitreous gel. Fibers or strands in this gel cast shadows on the retina that are perceived as floaters. The retina is the “film” on the back surface of the eye that helps transmit the images we see to the brain.
As a person ages, the vitreous gel can liquefy and separate from the retina. This separation can place traction and “pull” on the retina. This pulling on the retina is perceived by some people as a flash of light. If the gel is abnormally adherent to the retina, or the retina is weak in a certain area, a retinal tear can occur. This tear in the retina can also be perceived as a flash. Retinal tears can also lead to bleeding into the vitreous gel. This blood looks the same as a typical floater in the person’s field of vision.
Once a retinal tear develops, there is a significant risk of the liquid vitreous going through the break and causing a retinal detachment. A retinal detachment is a serious and potentially blinding eye condition that requires surgical intervention.
Flashes of light may also be a symptom of migraine headache or an “ophthalmic migraine”. This can only be differentiated by a thorough dilated eye examination.
If a person notices a new floater and/or new onset of light flashes, he or she should be urgently examined. We will put drops in the eye to dilate the pupil and carefully observe the retina and vitreous. It is important to rule out the possibility of a torn retina. If a tear is diagnosed, it can be treated in the office with laser, and prevent the development of a retinal detachment.