Cystoid Macular Edema (CME): Causes, Symptoms and Treatment

Cystoid macular edema (CME) is a condition that occurs when blood vessels in your retina leak fluid into a part of your eye called the macula. This can cause fluid buildup causing your macula to swell. Swelling due to fluid accumulation is called edema.

Your macula is part of your retina, which is a layer of tissue at the back of your eye. This is the part of your eye that helps you see colors and fine details.

Macular edema can cause blurred vision and changes in the way you see colors – over time it can even lead to loss of central vision. Central vision is what you can see by looking straight ahead.

The most common causes of macular edema are diabetic retinopathy and age-related macular degeneration (AMD). Read on to learn more about the mechanisms of macular edema, its symptoms, and available treatments.

Macular edema occurs when fluid enters your macula and causes it to swell. The fluid usually comes from damaged blood vessels in your retina.

These damaged blood vessels can occur due to several factors, including:

  • Diabetes. Diabetic macular edema (DME) is a complication of diabetes and the most common cause of vision problems in adults under the age of 65. DME results from a diabetes-related eye disease called diabetic retinopathy. High blood sugar can increase the risk of developing diabetic retinopathy and damage the blood vessels in your retina.
  • Eye operation. Your risk of macular edema increases after any type of eye surgery, including surgery for glaucoma, cataracts, or retinal disease. Macular edema that occurs after eye surgery is normally mild and temporary.
  • Age-related macular degeneration (AMD). AMD is a common eye condition that causes central vision loss. One type of AMD, wet AMD, is caused by growth of abnormal blood vessels in your retina which then leak into your macula and cause damage. It can also cause macular edema.
  • Blocked retinal blood vessels. Inflammation, atherosclerosis, high blood pressure, glaucoma, or other conditions can sometimes block retinal blood vessels. When this happens, blood doesn’t flow properly and can seep into your retina. This fluid can then seep into your macula and cause macular edema.
  • Swelling of the retina. Multiple inflammatory diseases can cause swelling of the retina and macula. These diseases can break down your macula tissue and lead to eye damage.
  • Aging. As your eye ages, the gel between the lens and the retina, called the vitreous, begins to loosen. Sometimes it does not come off completely and pulls on the macula. This can lead to swelling and scar tissue.
  • Genetic conditions. Certain genetic conditions, such as retinoschisis, can cause macular edema.
  • Eye tumors. Both cancerous and benign eye tumors can cause macular edema.
  • Eye injuries. An injury to the eye can lead to macular edema.

Macular edema usually causes no pain.

At first, you may not notice the symptoms of vision changes. But when symptoms do occur, they often include:

If you notice any of these symptoms, you should see an eye doctor. Some of these symptoms can occur with other conditions, but macular edema can cause significant vision loss or even blindness without treatment.

An eye doctor will likely perform a series of tests to confirm a diagnosis of macular edema. They will often start with a thorough eye exam and discuss your medical history.

After that, they can perform several tests, including:

  • Visual acuity. A visual acuity test involves reading an eye chart. You will read letters of different sizes to test the strength of your vision.
  • Dilated eye exam. A dilated eye exam is done using special eye drops that widen your pupils. This allows an eye doctor to see your retina more clearly.
  • Amsler grid. An Amsler grid is a visual test where you look at a grid and say whether you see the grid lines as straight or wavy.
  • Fluorescein angiography. This test is done by injecting a dye into your arm. The dye travels through your blood vessels and helps highlight damaged blood vessels in your eyes. A camera is then used to take pictures of your eye and the highlighted blood vessels.
  • Optical coherence tomography. This test uses a specialized light and camera to take detailed images of the cell layers of your retina.

The right treatment for your macular edema depends on the underlying cause and the extent of the damage.

When caused by injury or surgery, macular edema can be temporary and may even go away on its own.

If the cause is diabetes or inflammatory eye conditions, macular edema is progressive and requires prompt treatment. In these cases, vision loss caused by macular edema can be reversed if detected early. But treatment can stop the progression of macular edema before vision loss becomes significant.

People with diabetes and others at increased risk for macular edema should have regular dilated eye exams. This helps doctors spot the condition early on, when it is more manageable and even reversible.

Common treatments include:

  • Anti-VEGF injections. Anti-VEGF injections are the most common treatment for macular edema. These treatments stop the growth of blood vessels in your eyes. This slows macular edema and prevents further damage.
  • Anti-inflammatory treatments. Anti-inflammatory treatments can reduce eye swelling caused by inflammatory eye disease. Corticosteroids in the form of eye drops, pills, or injections are the most common anti-inflammatories used for macular edema.
  • Vitrectomy. A vitrectomy can be performed when the macular edema is caused by the pulling of the vitreous on the macula. This surgery removes the vitreous body so that it no longer stresses the macula.

A variety of conditions and factors can cause macula edema, including diabetes, inflammatory eye conditions, AMD, and eye aging. The cause of your macular edema will determine the most effective treatment options for you.

Any vision loss caused by macular edema can be reversed when caught early, which is why it’s important to see an eye doctor for any unusual eye symptoms. Early treatment can minimize vision loss and prevent further damage.

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