As described in the anatomy section, the macula is the center part of the vision and is the focal point of light on the retina. This is the portion of the retina that sends finely focused messages to your brain that allows you to read and discriminate objects clearly with the eye. One problem that can cause decreased vision in patients is macular edema. This "swelling" of the macula can occur in various conditions including after cataract surgery, diabetes, inflammations of the eye, tumors, and in other abnormalities. Diabetic macular edema is discussed in the section on diabetic retinopathy and we will focus this discussion on macular edema occurring after cataract surgery.
Macular edema occurring after cataract surgery is called cystoid macular edema (CME). Following cataract surgery and in other inflammations of the eye, the blood vessels may become irritated in the center part of the vision and become leaky, leaking serum into the retina. As serum leakage occurs into the normally dry retina, which is really a compact layer of neurological tissue, it thickens much like a dry sponge turning into a wet sponge. With this thickening vision can decrease from the damage to the neurological tissue in the center part of vision. This leakage and thickening is called "edema" thus the name macular edema. Eye care specialists looking at the edema in the eye can many times see small cysts of fluid and particularly on fluorescein angiography, a dye test done to diagnose macular edema, these cysts can readily be seen. Thus, the reason for the name "cystoid macular edema" (CME).
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Cystoid Macular Edema Fluorescein angiogram of CME after cataract surgery. Fluorescein is white in this late phase angiogram showing the cysts that form from leakage of serum from the blood vessels near the center of vision and causing decreased vision. |
CME usually occurs within several months following cataract surgery and if it occurs in one eye there is an approximately 50% chance that it will occur in the second eye with cataract surgery. Generally, however, CME resorbs on its own and the vision returns to normal. In some instances CME will not clear and therapy is indicated. The usual treatment will be first a series of eye drops to fight inflammation (anti-prostaglandin medications and steroids). Drops alone are effective in many patients, however, if not effective the treatment may proceed to injection of steroids around the eye or into the eye and finally to vitrectomy surgery if all of the above are not effective.
Much research is underway to determine the causes of the various macular edemas including cystoid macular edema and to develop newer therapies to treat the inflammation after cataract surgery and from other causes to treat this disorder. The good news is that most patients who develop cystoid macular edema will clear and vision will return to normal.
Disclaimer Stuff: The opinions expressed in this website are those of RVT. Diagnosis and therapy should be based on a thorough examination by and recommendations of a qualified eye provider.