Cystoid Macular Edema (CME)

What Is Cystoid Macular Edema (CME)?

Cystoid macular edema or CME, is a painless disorder which affects the central retina or macula. When this condition is present, multiple cyst-like (cystoid) areas of fluid appear in the macula and cause retinal swelling or edema.


  • Blurred or decreased central vision (the disorder does not affect peripheral or side-vision)

The symptom described above may not necessarily mean that you have cystoid macular edema. However, if you experience this symptom, contact your eye doctor for a complete exam.


Although the exact cause of CME is not known, it may accompany a variety of diseases such as retinal vein occlusion, uveitis, or diabetes. It most commonly occurs after cataract surgery.

Risk Factors

About 1-3 % of those who have cataract extractions will experience decreased vision due to CME, usually within a few weeks after surgery. If the disorder appears in one eye, there is an increased risk (possibly as high as 50%) that it will also affect the second eye. Fortunately, however, most patients recover their vision with observation or treatment.

Treatment and Drugs

Because many factors can lead to CME, effective treatment will vary. After the diagnosis has been made and confirmed, your ophthalmologist may attempt several kinds of treatment. Retinal inflammation is usually treated with anti-inflammatory medications such as corticosteroids. These are usually given as eye drops, though occasionally they must be administered as an injection or by mouth. Ophthalmologists may also inject the eye with medications in the vascular endothelial growth factor (VEGF)- inhibitor class of drugs or perform a laser procedure to eliminate the macular edema. Also, diuretics, such as acetazolamide (Diamox), may help to reduce the swelling in certain cases.

Sometimes, the vitreous (the gel that fills most of the back of the eye) pulls on the macula causing CME. A vitrectomy (surgery to remove the vitreous gel) may be needed in those situations.

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Reviewed by Grant M. Comer, M.D., M.S.