Floaters are movable spots that can appear in your field of vision. Eye floaters may look like black or gray particles that move along with eye movement. Flashes are perception of brief arcs or flashes of light that you may experience even in a dark room where no light is actually flashing.
Floaters and flashes can be caused by any of the following:
Age-related changes of the eyes: Age-related changes in the vitreous (jelly-like material inside the eye) causes it to liquefy and pull away from the interior surface of the eyeball where it is attached to the retina. This process is called posterior vitreous detachment (PVD) and occurs mostly in people between the ages of 40 and 70. The vitreous pull on the retina during PVD can normally be experienced as bright flashes of light. Vitreous becomes clumped, and string-like due to shrinkage and sagging. Pieces of this debris can block some of the light passing through the eye and form shadows on your retina, which you may experience as floaters.
Posterior uveitis: inflammation in the layers of the uvea in the back of your eye
Vitreous hemorrhage: bleeding into the vitreous of the eye
Retinal tear: if the sagging vitreous pulls out with enough force to tear the retina it can cause floaters to appear. Retinal tears can lead to retinal detachment and if left untreated can cause permanent loss of vision.
Your eye doctor will place pupil-dilating drops and conduct a complete eye examination in order to find the cause of floaters and flashes in your eyes.
Floaters and flashes will normally disappear over weeks or months. If however, the symptoms persist and adversely affect your vision; your doctor may recommend surgery called vitrectomy. During this procedure, a small incision is made in your eye and the jelly-like vitreous is removed. A solution is temporarily placed in the eye to prevent it from losing its shape until your body makes and fills your eye with enough fluid that replaces the solution. There is no guarantee that vitrectomy will remove all the floaters in your vision as new floaters can always develop after surgery. As with any surgical procedure, vitrectomy has its own risks and complications, which include elevated pressure in the eye leading to glaucoma, bleeding, injury to the retina, and eye infections.
Flashes and floaters are usually harmless and go away with time; however, they can also indicate more serious conditions such as posterior vitreous detachment, retinal tear, or retinal detachment, which if left untreated can lead to severe loss of vision.