What is cystoid macular edema?

Cystoid macular edema, commonly called CME, is a painless disorder which affects the retina, the light-sensitive inner lining of the eye.  When this condition is present clear fluid fills multiple cyst-like (cystoid) formations in the macula, the portion of the retina responsible for central or "straight ahead" vision.  This creates macular swelling, or edema.

Although the exact causes of CME are not known, it may accompany a variety of diseases such as retinal vein occlusion, uveitis or diabetes.  It most commonly occurs after cataract surgery.  About three percent of those who have cataract extractions will experience decreased vision due to CME in the first year, usually from two to four months after surgery.

If the disorder appears in one eye, there is an increased risk - as high as 50% - that it will also affect the second eye.  Fortunately, however, most patients recover their vision after some time.

What are the symptoms of CME?

The most common symptom of cystoid macular edema is blurred or decreased central vision (CME does not affect the peripheral or side vision).  There may also be painless retinal inflammation or swelling.  However, the condition may be present even when no visual loss occurs.  In these cases it is diagnosed by an ophthalmologist after a thorough medical eye examination, usually using a photographic test called a fluorescein angiogram.

How can CME be treated?

Since many factors can lead to CME, it is not possible to say which treatment, if any, will prove effective.  After the diagnosis has been made and confirmed, the ophthalmologist may attempt several kinds of treatment.  Signs of retinal inflammation are usually treated with anti-inflammatory medications, including cortisone-like drugs (steroid drops, pills or local injections) or anti-inflammatory drugs like indomethacin.  Diuretics such as Diamox® may help to reduce the swelling in some cases.

If the vitreous (the clear, gel-like substance that fills the center of the eye) is believed to be the source of the problem, laser surgery might be recommended.  Another procedure called a vitrectomy can be used to suction the vitreous out of the eye and replace it with a clear solution.

In some cases, the swelling and inflammation which accompanies CME can bring on glaucoma, a disorder which often occurs due to increased pressure within the eye.  When this happens, the glaucoma must be treated with appropriate medications to reduce the pressure.

A great deal of research is presently being conducted to determine the causes of cystoid macular edema.  Hopefully, this research will lead to more exact prevention and treatment measures in the near future.

Why are regular eye examinations important for everyone?

Eye disease can strike at any age.  Many disorders, like CME, do not always produce immediate symptoms.  Since most serious vision loss is preventable if diagnosed and treated early, regular examinations by an ophthalmologist are very important.

©1992 American Academy of Ophthalmology