Floaters are dark spots or strands seen in a person's field of vision, caused by the accumulation of debris in the clear, gel-like material (vitreous) in the eye. Floaters can indicate a serious eye disorder or can be a harmless side effect of aging.
Floaters look to a person like black or gray dots, strings, or occasionally blobs seen in that person's field of vision. Floaters usually move as the eye moves and are most noticeable when the individual looks with one eye at a time at a plain bright background such as the blue sky, a plain white piece of paper, or a white wall. Sometimes floaters are accompanied by flashes of light, especially at the edges of the field of vision. These flashes continue even when the eyes are shut. There is no pain associated with either floaters or light flashes. Normally floaters appear in only one eye at a time.
Floaters are most likely to occur in people over age 50. The occurrence of floaters is strongly linked to age, but is independent of race or gender. Severely nearsighted people are more likely to have difficulty with floaters due to the shape of their eyes.
QUESTIONS TO ASK YOUR DOCTOR
- Do I have posterior vitreous detachment? Are there any retinal tears or holes?
- What should I do if I continue to be bothered by floaters?
- Is it likely that I will develop floaters in the other eye?
- What changes in my vision should cause me to seek additional medical treatment?
- Would you recommend that I see a retina specialist?
- How often do you recommend that I have eye examinations?
Causes and symptoms
Between the clear lens of the eye and the light-sensitive retina at the back of the eye lies the vitreous. This material fills about 80% of the eyeball and has a consistency similar to that of the white of an uncooked egg. As a person ages, the vitreous begins to liquefy and shrink. This is a normal aging process and the liquefying of the vitreous does not cause loss of vision.
The retina has millions of tiny microscopic fibers enmeshed in the vitreous. As the vitreous shrinks, these fibers pull loose and some of them form tiny clumps in the vitreous. The floaters that a person sees in the field of vision are shadows on the retina made by these clumps or strings of fibers. Sometimes as the vitreous pulls these microscopic fibers off the retina, the retina is stimulated and the person sees flashes of light that are not coming from the environment. These light flashes are the result of optic nerve stimulation.
The process of shrinkage of the vitreous away from the retina is called a posterior vitreous detachment (PVD). PVDs are common and normally the only effect they have on vision is to create annoying floaters and occasional light flashes. However, in some people, as the vitreous pulls away it creates a hole or tear in the retina. Fluid from the vitreous then can seep between the retina and the cells underneath the retina. When the retina is separated from the cells beneath it, the retina is said to be detached and some vision is lost. The symptom of a retinal detachment is the perception of a black curtain that covers a portion of the field of vision. Retinal detachment is a medical emergency that can lead to blindness and requires immediate medical attention. Most often retinal tears also create a shower of new floaters. Anyone experiencing more than a few floaters should see an ophthalmologist promptly for a complete eye examination .
Floaters can also be caused by a blow to the head. Large numbers of floaters that appear suddenly suggest that a blood vessel has ruptured and blood cells have entered the vitreous. Another cause of floaters is inflammation of the eye (uveitis), a condition that needs prompt medical treatment. Some other people see spots in their vision for half an hour or so before developing a migraine headache. These spots may appear in both eyes simultaneously. Migraine floaters are not related to PVD.
The patient reports floaters to an optometrist or ophthalmologist. The doctor then confirms their presence by dilating the pupil and examining the interior of the eye with an ophthalmoscope. At the same time, the examiner checks for posterior vitreous detachment, and retinal holes or tears.
Floaters normally are not treated. Eventually the eye adjusts to them and in time gravity tends to pull the floaters below the field of vision. In cases of retinal detachment or in very rare cases where floaters are so dense as to interfere with vision, a serious operation called a vitrectomy may be performed. In a vitrectomy, the vitreous in the eye is removed, which also removes the floaters. The space the vitreous occupied is then filled with fluid. This is a very delicate operation with the potential for serious complications. This operation is rarely performed to remove floaters because the risks usually outweigh the benefits.
Prognosis depends on the cause of the floaters. In most cases, floaters are annoying but harmless, and they eventually either disappear or become less intrusive. Nevertheless, large numbers of new floaters often precede a retinal hole, tear, or detachment. A retinal detachment, and sometimes other retinal damage, may require surgery to preserve vision. Depending on the location of the retinal damage, there may be permanent vision loss.
Optometrist —A healthcare professional licensed to perform routine eye exams, prescribe corrective lenses, diagnose disorders of the eye and treat or refer for treatment certain disorders.
Ophthalmoscope —An specialized lighted instrument used to view the interior of the eye.
Ophthalmologist —A medical doctor who specializes in diagnosing and treating eye disorders.
Retina —Light-sensitive tissue on the back of the eye that receives images and converts them into nerve impulses to be sent to the brain by way of the optic nerve.
Floaters cannot be prevented. They are considered a normal part of aging.
Floaters can be quite disconcerting, especially if accompanied by flashes of light. Caregivers need to promptly arrange a complete eye examination if the person they care for could be confusing complains of floaters. A person who complains of a black cloud or black curtain in the field of vision may be experiencing a medical emergency and needs to see an eye specialist immediately, as this may be a sign of a detached retina. Caregivers also need to remind the person in their care to check the vision periodically for floaters by putting a hand over first one eye and then the other while looking at a white wall or white paper. Individuals with dementia may have difficulty explaining what they are experiencing.
Gordon, Sandra. The Aging Eye. New York: Fireside, 2001. Kitchen, Clyde. Fact and Fiction of Healthy Vision: Eye Care for Adults and Children. Westport, CT: Praeger Publishers, 2007.
Margo, Curtis E., and Lynn E. Harman. “Posterior Vitreous Detachment.” Postgraduate Medicine 117, no. 3 (March 2005): 37–42. Available online at http://www.postgradmed.com/issues/2005/03_05/margo.htm.
“Eye Floaters.” MayoClinic.com. December 18, 2007 [cited February 16, 2008]. Mayo Foundation for Medical Education and Research. http://www.mayoclinic.com/health/eye-floaters/DS01036.
“Facts About Floaters.” National Eye Institute. December 2007 [cited February 16, 2008]. http://www.nei.nih.gov/health/floaters/index.asp.
“Optometric Clinical Practice Guideline: Adult Eye and Vision Examination.” American Optometric Association. April 28, 2005 [cited February 16, 2008]. http://www.aoa.org/documents/CPG-1.pdf.
“Spots and Floaters.” American Optometric Association. [cited February 16, 2008]. http://www.aoa.org/x4701.xml.
American Optometric Association, 243 N. Lindbergh Blvd., St. Louis, MO, 63141, (800) 365-2219, http://www.aao.org.
EyeCare America Foundation of the American Academy of Ophthalmology, P.O. Box 429098, San Francisco, CA, 94142-9098, (877) 887-6327, (800) 324-EYES (3937), (415) 561-8567, [email protected], http://www.eyecareamerica.org.
Tish Davidson AM