Macular Edema

Macular edema. National Eye Institute / National Institutes of Health

Macular edema is swelling or fluid retention in a specialized part of the retina called the macula. The macula is located in the back of the eye and provides us with clear, central vision. It is the part of the retina we use when we "aim" our vision to look at a target. Fluid can build up in the macula from abnormal, leaking blood vessels. When macula edema occurs, central vision becomes distorted or decreased.

What causes macular edema?

Macular edema can be a sign or symptom of many other conditions. Diabetes is the most common cause of macular edema. Macular edema is also common in people that have uncontrolled high blood pressure. Certain eye diseases, such as retinitis pigmentosa and uveitis can also cause macular edema. Macular edema can also be a complication of eye surgery. Certain medications used to treat glaucoma such as latanoprost (Xalatan) have also been known to cause macular edema.

How do doctors diagnose macular edema?

Doctor will first listen to your complaints and elicit a medical history, such as having diabetes or having recent eye surgery. Next, they will measure your visual acuity by having you cover one eye and reading letters on an eye chart. Typically, macular edema causes vision to become blurred. Doctors may also give you a test called an Amsler Grid to see if your vision is become not only blurred, but distorted.

Special eye drops will be administered to dilate your pupil so that the inside of the eye can be visualized. Macular edema in many cases can be seen just by looking at your macula with a slit lamp microscope. However, more subtle cases are difficult to see. In this case, an OCT will be performed. An image from an OCT can allow doctors to view individual layers of the retina.

 Optical Coherence Tomography is a non-invasive test that uses light to obtain images where macular edema can be seen very easily. Sometimes doctors may also use a dye-injection test so that blood flow can be analyzed through the macula.

How is macular edema treated?

Macular edema is treated differently depending on the underlying cause. For example, if uncontrolled diabetes or high blood pressure is the cause, treatment may be aimed at controlling those conditions first. However, if symptoms are severe or if the doctor is concerned that the edema can cause vision loss or damage, it will be treated with medications or injections.

Often, a non-steroidal anti-inflammatory drug (NSAID) is prescribed in the form of an eye drop. This may have to be taken for several weeks and sometimes months to control the edema. Doctors will also prescribe corticosteroids the form of a topical eye drop or oral pills. Corticosteroids can also be injected in or around the eye.

Another class of drug called anti-VEGF (vascular endothelial growth factor) drugs are being injected directly into the eye.

 This fairly new class of drug act to shrink existing abnormal blood vessels and to prevent the growth of new leaky blood vessels.

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