Macular Edema

Macular edema
National Eye Institue / National Institutes of Health

The macula is a specialized part of the central retina. The macula allows us to have detailed, sharp vision. It is the part of our eye we use when we look directly at an object. The macula is a very small part of our retina and when it becomes disrupted, we can usually tell something is not quite right with our vision. Some conditions cause the macula to become swollen or edematous. When this occurs, fluid abnormally collects in this area and often creates a cystic type appearance.

When the fluid collects in little cysts, doctors call it cystoid macular edema.

Symptoms of Macula Edema

Some people have such mild edema that they do not have symptoms. However, when the swelling becomes more severe, symptoms may include the following:

  • Blurred vision
  • Distorted vision
  • Color vision changes
  • Missing spots in the central vision

Causes of Macular Edema

There are several reasons why someone could develop macular edema.

Diabetes: When diabetic patients develop macula edema, it is referred to as DME or diabetic macular edema. DME develops from leaking blood vessels, a process that occurs when a diabetic person develops diabetic retinopathy.

Eye surgery: Cystoid macular edema is a relatively common complication of cataract surgery. Although the exact mechanism is not clear, it is thought to have something to do with inflammation and the fact that surgeons are creating a potential space when the eye’s natural lens is removed.

Sometimes fluid or inflammation makes its way back to the macula.

Vein occlusions: People with cardiovascular disease are at risk for branch or central retinal vein occlusion. When a retinal vein becomes occluded, the passage of fluid and blood is blocked. Fluids begin to leak into the surrounding retina including the macula.

Age related macular degeneration: Macular degeneration causes pigmentary changes and sometimes blood vessels underneath the macula can break through the underlying tissue and leak fluid causing macular edema.

Diagnosing Macular Edema

Macular edema is diagnosed by taking a very good, central visual acuity measurement. Anything worse than 20/20 can be a cause for concern. Next, the doctor may perform an Amsler Grid exam. The Amsler Grid is an easy way to check for distortions or missing spots in your central vision. The doctor will then dilate your pupils with dilating drops so that the macula and retina can be viewed easily. If the doctor feels that there may be macular edema, most likely the first test to be ordered will be optical coherence tomography or OCT. An OCT is a test that uses light waves and reflections instead of sound waves or X-rays to view fine detail of the macula. The OCT is non-invasive and easy to perform. To confirm the diagnosis, doctors may perform fluorescein angiography or FA.

An FA is a dye-injection test that uses a special retinal camera to view macula edema.

Treating Macular Edema

Treatment of macula edema depends on what is causing it. Your optometrist or ophthalmologist will most likely prescribe an NSAID drop as a first line treatment. A NSAID drop is a non-steroidal anti-inflammatory eye drop. These eye drops are sometimes taken for a few months. If the condition does not resolve, you will be referred to a retinal specialist. Retinal specialists may inject drugs directly into the eye to treat edema. Although becoming rare, sometimes, a retinal specialist will use a laser to treat macular edema.

Source:  Rotsos TG, Moschos MM. Cystoid macular edema. Clin Ophthalmol. Dec 2008.

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