What do diabetes, eye surgeries, and aging have in common? They’re three of the 10 main causes of macular edema, a condition where fluid builds up and causes swelling in the center of your 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 to be aware of if you’re living with diabetes. 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 your 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 your retina and macula. Macula edema is diagnosed with eye exams and imaging tests, such as optical coherence tomography (OCT) 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 developing eye problems. This is because high blood sugar levels can damage the delicate blood vessels that bring oxygen and nutrients to the retina. Damaged blood vessels then leak fluid into the eye, causing a condition known as diabetic retinopathy. When fluid builds up in the macula, it’s 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 your eyes to produce vascular endothelial growth factor (VEGF) proteins. These proteins are responsible for creating new blood vessels. However, in people with DME, VEGF causes abnormal blood vessels to grow in the eye that are leaky and 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. In non-center-involved DME, peripheral vision outside the center is affected.

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

• Anti-VEGF treatment by intravitreal injections (into the eye) to block VEGF proteins
• Corticosteroids or nonsteroidal anti-inflammatory drugs (NSAIDs), which reduce inflammation
• Eye surgery or laser treatment, such as photocoagulation

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 of AMD. 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 causes central vision problems. It makes it hard to see shapes, colors, objects, and faces clearly and makes everyday activities like driving and reading difficult. People with wet AMD lose visual acuity (clarity) faster than those with dry AMD.

Risk factors that increase your chances of developing 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 your retina becomes clogged or blocked by a blood clot. Pressure builds up 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.

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

If CRVO is left untreated, the nerve cells in your eyes 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 the cells in the retina break down slowly 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 theories. 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

Macular pucker is a rare eye condition that causes bulges, creases, or wrinkles on your macula. Aging is the most common risk factor for the condition, as the vitreous or gel-like substance in your eyes shrinks. If it gets stuck on the macula, scar tissue forms and makes the macula pucker. When your macula isn’t lying 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 is an inflammatory eye condition that causes inflammation of the uvea — the middle layer of the eye (including the iris and the layer just under the retina). In intermediate uveitis, your immune system attacks your eyes and damages your 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, 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

Although not as common, some people develop macular edema after eye surgery to treat glaucoma, cataracts, or problems with their retina. Your eye’s sensitive tissues can become inflamed after a procedure, leading to swelling in the macula. For example, you have a higher risk of developing cystoid macular edema after cataract surgery. 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 prescribing medications, 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 — including rosiglitazone (Avandia) and pioglitazone (Actos) — have been found to cause cystoid macular edema. Fortunately, most cases improve once the medication is stopped. If your symptoms continue, your doctor can prescribe anti-inflammatory drugs to help. Rosiglitazone in particular is rarely prescribed now by physicians because of its side effects.

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 to your eye specialist if you were recently hit in the eye and are experiencing vision changes.

Talk to Your Doctor About Macular Edema

If you have diabetes and you’re 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. If you’re diagnosed with macular edema, your treatment plan will be based on what’s causing your macular edema and how severe your symptoms are.

The overall goal of treating this condition is to control swelling, inflammation, and leaky blood vessels to improve vision or prevent further damage to the eyes. Examples of treatments include:

• Injections into the eye
• Prescription eye drops
• Surgical or laser treatments

If you’re living with diabetes and other long-term health conditions, visit your eye care specialist annually for regular eye exams. They can check your eye health and look for any signs of macular edema or other damage to ensure that you get early treatment. This is the best way to preserve your vision for years to come.

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