What do diabetes, eye surgeries, and aging have in common? They’re three of the 10 main causes of macular edema, a condition in which fluid builds up and causes swelling in the center of the retina. Without treatment, macular edema can lead to vision problems and, over time, even vision loss.

In this article, we’ll cover the 10 main causes of macular edema. With this knowledge, you can be better prepared to talk with your doctor if you begin experiencing new vision symptoms.

What Is Macular Edema?

The macula is the central part of the retina, the light-sensitive tissue in your eyes that sends signals to the brain and produces vision. The retina is found at the back of the eye and is connected to the optic nerve. Damage to this important tissue can lead to vision impairment or loss.

Macular edema occurs when leaky blood vessels cause blood and fluid buildup in the macula, the part of the retina that allows us to see colors and fine details. Pressure from the fluid buildup causes edema (swelling) and thickening in the retina and macula. Macular edema is diagnosed using eye exams and imaging tests, such as optical coherence tomography or fluorescein angiography.

Symptoms of macular edema include:

• Blurry vision that worsens over time
• Wavy vision, especially when looking straight ahead (central vision)
• Colors that look faded or dull
• Objects that appear to be different sizes when seen with one eye versus the other

So, what causes macular edema? Here, we’ll break down 10 causes, including underlying health conditions, surgery, and injuries.

1. High Blood Sugar Levels From Diabetes

People with both type 1 diabetes and type 2 diabetes have a higher risk of eye problems. This is because high blood sugar levels can damage the delicate blood vessels that bring oxygen and nutrients to the retina. Fluid can then leak into the eye, causing a condition called diabetic retinopathy. Fluid buildup in the macula is known as diabetic macular edema (DME).

In people with diabetes, high blood sugar levels can damage the delicate blood vessels that bring oxygen and nutrients to the retina.

Elevated blood glucose (sugar) levels also cause cells in the retina to produce vascular endothelial growth factor (VEGF) proteins, which are responsible for making blood vessels. However, in people with DME, VEGF causes leaky, abnormal blood vessels that don’t work properly. Without the right treatment, DME can lead to vision loss. In center-involved DME, central vision — what you see directly in front of you — is affected. Non-center-involved DME involves areas of the macula near but not including the center, which may cause mild vision changes.

Because DME can be a complication of diabetes, the first step in treatment involves controlling high blood sugar levels. Other treatment options include:

• Anti-VEGF treatments by intravitreal injections (into the eye) to block VEGF proteins
• Corticosteroids by intravitreal injections
• Eye surgery or laser treatment, such as photocoagulation

Because diabetic macular edema can be a complication of diabetes, the first step in treatment involves controlling high blood sugar levels.

Can You Get Macular Edema Even if You Don’t Have Diabetes?

Yes, diabetes is a common cause, but it’s not the only one. Other factors such as aging, blocked veins in the eye, inflammation, eye surgery, injuries, and certain medicines, can also cause fluid to build up in the macula and make it swell.

2. Age-Related Changes in Your Eyes

As we age, the tissues in our eyes begin to change. Some people develop age-related macular degeneration (AMD), which damages the macula. There are two types of AMD — wet and dry.

Wet AMD is the more serious form. Similar to DME, in wet AMD, VEGF proteins cause new abnormal blood vessels that leak fluid and blood into the macula. This leakage leads to swelling and scar tissue formation that cause central vision problems, making it hard to see shapes, colors, objects, and faces clearly. Everyday activities like driving and reading can also be more difficult. People with wet AMD lose visual acuity (clarity) faster than those with dry AMD.

Risk factors that increase your chances of AMD include:

• Being 50 or older
• Smoking
• Eating a diet with too much saturated fat
• Having untreated hypertension (high blood pressure)

Anti-vascular endothelial growth factor injections can treat wet AMD and related macular edema by stopping new, leaky blood vessel formation. Photodynamic therapy — a combination of laser therapy and medications — can also help prevent further vision loss.

3. Blockages in Your Eyes’ Veins

Your veins carry blood from your body back to your heart. Blockages in these blood vessels can cause various health problems. Central retinal vein occlusion (CRVO) develops when the vein carrying blood from the retina gets clogged or blocked by a blood clot. Pressure builds in the eye behind the blockage, causing blood and fluid to leak into the retina. Macular edema can develop from this leakage, leading to central vision loss.

If CRVO is left untreated, the eye’s nerve cells can’t get enough oxygen and nutrients, and they die.

4. Genetic Eye Diseases

Retinitis pigmentosa refers to a group of rare genetic eye diseases in which cells in the retina break down over time. Researchers estimate that between 10 percent and 50 percent of people with retinitis pigmentosa are affected by cystoid macular edema. Doctors and researchers aren’t sure why this is the case, but they have some ideas. One theory is that the breakdown of the blood-retinal barrier — which lets fluid leak into the eyes — causes fluid-filled cysts to form on the macula, leading to swelling and vision loss.

5. Macular Pucker

A rare eye condition called macular pucker causes bulges, creases, or wrinkles on the macula. The most common risk factor is aging, as the vitreous or gel-like substance in the eyes shrinks. If it gets stuck on the macula, scar tissue forms and makes the macula pucker. If your macula isn’t flat against your eye, you’ll have wavy, blurry, or dull vision. This unevenness leaves space underneath the macula for fluid to collect, leading to macular edema.

6. Inflammation of the Eye

Uveitis causes inflammation of the uvea — the eye’s middle layer (including the iris and the layer just under the retina). In intermediate uveitis, the immune system attacks the eyes and damages the retina’s blood vessels. If it’s left untreated, uveitis can eventually lead to macular edema and vision loss. Symptoms of uveitis include red, painful eyes, as well as floaters (dark spots in your vision) and sensitivity to light.

7. Eye Tumors

Both malignant (cancerous) and benign (noncancerous) eye tumors can cause macular edema. Most benign tumors don’t cause vision loss — however, if they develop in the macula, they may cause central vision loss. Choroidal tumors are cancerous tumors that can cause cystoid macular edema. This is likely due to inflammation and leaky blood vessels around the tumor.

8. Eye Surgeries

Less commonly, macular edema can develop after eye surgery to treat glaucoma, cataracts, or problems with their retina. The eye’s sensitive tissues can become inflamed after a procedure, leading to swelling in the macula. For example, after cataract surgery, you have a higher risk of cystoid macular edema. It tends to go away within three to four months after surgery.

It's possible to develop macular edema after eye surgery to treat glaucoma, cataracts, or retinal issues.

9. Certain Medications

When considering treatment options, you and your doctor will weigh the benefits of the drug and its potential side effects. Some medications for cancer, autoimmune diseases like multiple sclerosis, and diabetes can also lead to cystoid macular edema. One diabetes drug, rosiglitazone, is seldom prescribed in the United States — it was restricted in 2011 to heart risks (though those restrictions were lifted in 2013). Another drug, pioglitazone, is still used but carries warnings because it can cause the body to hold on to extra fluid, which in rare cases may affect the eyes.

10. Eye Injuries

Injury or trauma to the eye can also cause macular edema. Common causes of eye injuries include falling or playing sports. Commotio retinae, or Berlin’s edema, is caused by retinal damage from trauma. It can affect your macula or the outer edges of your retina. Be sure to talk with your eye specialist if you were recently hit in the eye and notice vision changes.

Talk to Your Doctor About Macular Edema

If you have diabetes and are experiencing new changes in your vision or signs of macular edema, talk with your diabetes care team. They can refer you to an ophthalmologist (a physician who specializes in eye diseases) to diagnose and treat you.

When macular edema is diagnosed, the treatment plan depends on the cause and how severe the swelling is. The main goal is to reduce swelling, calm inflammation, and prevent further damage so that vision can be preserved.

For those living with diabetes or other long-term health conditions, yearly visits with an eye specialist are important. Regular exams help catch eye problems early and protect your sight for the future.

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