Flashes and floaters of the eye are usually the result of age-related changes to the vitreous, which is the thick gel firmly attached to the retina from birth. During the aging process, however, the vitreous becomes thinner and more watery, and at some point pulls away from the retina. This is known as a posterior vitreous separation or detachment (PVD). During PVD, tissue debris that was once secure in the firm vitreous gel loosens and moves around, casting shadows on the retina.
When this occurs, patients experience visual disturbances in the form of flashes of light, or floaters (specks or strands across the field of vision). These symptoms are not typically a reason for undue concern, but should, nonetheless, be evaluated by an ophthalmologist.
Causes of Flashes and Floaters
Flashes occur as a result of pressure on the retina, the bundle of nerves in the back of the eye where images are detected and transmitted to the brain. Such pressure causes patients to see either flashing lights or lightning streaks. Floaters occur when collagen fibers move across the vitreous and into the field of vision, causing patients to see specks, strands, webs or other shapes as the fibers cast shadows on the retina. Flashes and floaters are most visible when looking at a plain, light background.
Beyond simple aging, floaters or flashes appear most often in eyes that are injured, inflamed or nearsighted, and can be a result of the following:
- Cataract or YAG laser surgery
- Nearsighted vision
- Eye infections
- A blow to the head
- Injury to the eye
- Spasm of small blood vessels
The spasm (sudden constriction) of small blood vessels in the brain is also associated with migraine headaches.
Diagnosing Flashes and Floaters
Most people who develop PVD do not suffer further complications. For a small percentage of people, however, PVD is caused by retinal tears. A retinal tear is quite dangerous because it can lead to retinal detachment, which can seriously threaten vision. A sudden onset of symptoms, or momentary blindness in one section of the field of vision, is cause for concern. Patients who experience either should seek immediate medical attention.
Because symptoms may be the same regardless of the cause of the problem, it is important that anyone experiencing unfamiliar disturbances in vision have an examination in which the pupils are dilated; this is the only way in which a retinal tear can be accurately diagnosed. This is one of the reasons that it is crucial for patients to undergo thorough eye examinations on a regular basis.
For patients initially diagnosed as having uncomplicated PVD, a small percentage will go on to have retinal tears within 6 weeks, so it is important that they follow up with their doctors. For patients with underlying causative conditions, such as illness or injury, other treatments may be necessary.
Treatment of Flashes and Floaters
Although flashes and floaters are usually harmless and do not require treatment aside from regular monitoring, patients bothered by disturbances in their vision, or those experiencing significant visual interference, require medical intervention.
When treatment is necessary to reduce the appearance of flashes and floaters, it requires surgery to replace the vitreous gel. This procedure, known as a pars plana vitrectomy, removes the natural vitreous and replaces it with fluid.
In the case of a retinal detachment, emergency treatment is necessary to prevent serious complications. With treatment, most patients, even those with retinal tears, are able to maintain healthy vision.