Flashes & Floaters
Definition
The small specks or “bugs” that many people see moving in their field of vision are called floaters. They are frequently visible when looking at a plain background such as a blank wall or blue sky. Floaters were described long ago, in Roman times, as flying flies (“muscae volitantes”).
Flashes of light are often described as a camera flash, lightening, or fireworks going off in the eye.
Causes and Associations
Floaters are small clumps of cells or tissue that form in the vitreous gel. Although they appear to be in front of the eye, they are actually floating in the fluid inside the eye and are seen as shadows cast on the retina. Uncommonly, floaters result from inflammation within the eye or from crystal-like deposits which form in the vitreous gel. Posterior vitreous detachments occur because the vitreous liquefies with age and separates from the retina. Approximately two-thirds of 70-year-olds will have a posterior vitreous detachment.
Flashes are caused by stimulation of the retina, often by tugging by the vitreous gel. Flashes are also caused by a detaching retina.
Flashes and floaters are usually not serious, but there are exceptions. As the vitreous gel pulls away, the retina may be torn, sometimes causing a small amount of bleeding in the eye which may appear as a group of new floaters. Tears in the retina are potentially serious because they can lead to retinal detachment and visual loss.
Without examination by an ophthalmologist, there is no way for a person to determine whether floaters are serious. Any sudden onset of flashes of light should be evaluated promptly by your ophthalmologist.
Symptoms
Patients with Posterior Vitreous Detachment often have a large floater and transient flashes of lights.
Patients with Retinal Detachments often have a shower of floaters (black dots or cobwebs in their vision), flashing lights, and a shadow, curtain, or cloud progressing from their peripheral vision.
Examination
Complete and comprehensive ophthalmic examination is important in the assessment of flashes and floaters. Patients will receive vision testing, drops to dilate pupils, and a complete examination of the front and back of the eye. Pupillary dilation may create blurring, and therefore, it is often best if a driver accompanies the patient, although it is not absolutely required. When examining the retina, the ophthalmologist may depress the eye with a cotton tip applicator or other blunt instrument in order to view the entire retina to rule out tears.
What the Doctor Sees
In Posterior Vitreous Detachment, the ophthalmologist will see a clump floating in the vitreous. Approximately 10% of posterior vitreous detachments are associated with retinal tears or breaks. Sometimes a posterior vitreous detachment plucks a blood vessel and causes a vitreous hemorrhage, or bleeding into the vitreous, which has a greater association with retinal tears.
In Retinal Detachment, the ophthalmologist will see one or more breaks in the retina with underlying fluid. This can be accompanied by a vitreous hemorrhage.
Prognosis
In the absence of a retinal tear, vitreous clumps and posterior vitreous detachments are relatively benign. Floaters may sometimes interfere with clear vision, often when reading, and can be quite annoying. If a floater appears directly in your line of vision, the best thing to do is move your eye around, which will cause the inside fluid to swirl and allow the floater to move out of the way. We are most accustomed to moving our eyes back and forth, but looking up and down will cause different currents within the eye and may be more effective in getting the floaters out of the way. Often, floaters will break up or shift to the side with time, making them less noticeable or bothersome.
Prevention and Treatment
There is no way to prevent floaters due to vitreous clumps or posterior vitreous detachments. If associated with a retinal tear, a subsequent retinal detachment may be prevented by laser or freezing (i.e., cyrotherapy) treatment.
Retinal Detachment
Author: Allen C. Ho, M.D.
