Diabetic macular edema (DME) is a leading cause of vision loss in people with diabetes. It occurs when high blood sugar levels damage small blood vessels in the retina, the light-sensitive tissue at the back of the eye. These damaged blood vessels leak fluid into the macula, which is responsible for sharp, detailed vision, causing it to swell and resulting in vision changes.

DME affects more than 5% of people with diabetes, meaning more than 21 million people have the eye condition.

With early diagnosis and proper treatment, many people with DME can preserve their vision and maintain their quality of life.

DME develops gradually and may initially cause no noticeable symptoms. As fluid builds up in the macula, vision changes become more apparent, making daily tasks like reading and recognizing faces more difficult.

Symptoms can vary in severity and may include:

• Blurry vision: Objects may appear out of focus or wavy, making it hard to see fine details.
• Faded or dull colors: Colors may seem washed out or less vibrant than usual.
• Dark or empty spots in central vision: Some people experience areas of vision loss that make it harder to see straight ahead. Others may see floaters (dots or lines that float across their vision).
• Difficulty reading or seeing up close: Swelling in the macula can make it hard to focus on words or small objects.

DME symptoms can worsen over time if left untreated, potentially leading to severe vision loss or blindness.

Diabetic macular edema is a complication of diabetic retinopathy. Diabetic retinopathy develops when you have high blood glucose (the main sugar found in the blood) for an extended period, which can damage the small blood vessels in the retina.

As these blood vessels weaken, they may leak fluid or become blocked, decreasing oxygen to the retina. When this happens, the eye tries to grow new blood vessels that are prone to leaking or bleeding into the macula. If fluid builds up, the macula swells, leading to blurry or distorted vision.

Risk Factors

Certain factors may increase the risk of developing diabetic macular edema, including:

• History of diabetes: The longer someone has diabetes, the higher their risk of developing diabetic retinopathy and DME.
• Poor blood glucose control: High glucose (sugar) levels can lead to blood vessel damage and leakage.
• High blood pressure and cholesterol: Hyperlipidemia (high cholesterol) or hypertension (high blood pressure) can contribute to or worsen blood vessel damage in the retina. 
• Chronic kidney disease: These diseases, a common complication of diabetes, can cause weak kidney function and raise the risk of DME.
• Pregnancy: Hormonal changes during pregnancy can make it more challenging to manage blood sugar levels and increase the risk of DME.

Eye care doctors, including optometrists and ophthalmologists, can diagnose DME through a comprehensive eye exam. Even if your vision seems normal, an annual eye exam is one of the most effective ways to monitor your eye health and prevent complications.

In addition to reviewing your medical history, your eye care specialist may use the following diagnostic tests to diagnose DME:

• Visual acuity test: This test involves reading letters on an eye chart. It helps measure how clearly you can see at different distances. 
• Dilated eye exam: This involves using eye drops to dilate (widen) your pupils, allowing the eye care specialist to look at your retina and check for swelling and leaking blood vessels. 
• Optical coherence tomography (OCT): This imaging test creates detailed images of the blood vessels in and around the retina and measures macular thickness to detect fluid buildup. 
• Fluorescein angiography: This involves injecting a yellow dye into a vein in your arm. As the dye travels through your blood vessels, a camera takes photos of the blood vessels in the retina to check for leaking.
• Tonometry: This measures intraocular pressure (pressure in your eye) to rule out other eye conditions, such as glaucoma, that can affect vision.

The goal of treatment for DME is to reduce swelling in the macula, improve and preserve vision, and prevent further vision loss. There isn’t a cure, but early and ongoing treatment can help stabilize vision and, in some cases, improve it. Treatment options vary depending on the condition’s severity. 

Intravitreal Anti-VEGF Injections

Intravitreal injections involve placing anti-vascular endothelial growth factor (anti-VEGF) medications into the vitreous humor (part of the eye filled with a gel-like fluid). Anti-VEGF medications help slow down vision loss and sometimes improve vision by blocking a protein that promotes abnormal blood vessel growth and leakage.

Your eye care specialist will numb your eye to prevent pain and discomfort, with the injection taking only a few seconds.

Anti-VEGF medications include:

• Eylea (aflibercept) 
• Lucentis (ranibizumab) 
• Avastin (bevacizumab) 

Corticosteroid Injections

For some people, corticosteroid injections in the eye can help reduce inflammation and swelling in the retina. These may be used alongside anti-VEGF injections or as a standalone treatment option for people who don’t respond well or can’t safely undergo anti-VEGF therapy.

Corticosteroid injection medications include:

• Triamcinolone acetonide
• Ozurdex (dexamethasone implant) 
• Iluvien (fluocinolone acetonide)

Laser Therapy

Laser therapy involves applying small laser pulses to seal leaking blood vessels and reduce macular swelling.

Laser therapy can help stabilize and protect your sight but can’t reverse vision loss. It is generally safe, but possible risks include changes in light sensitivity, impaired night vision, and retinal scarring.

Vitrectomy 

Vitrectomy is a surgical procedure for severe or treatment-resistant DME. It involves removing the vitreous humor to treat structural changes causing macular swelling.

This procedure may help remove advanced glycation end products (AGEs) that could pull on the macula and worsen DME. AGEs are harmful compounds caused by chronic (long-term) high blood sugar that contribute to inflammation and retinal damage. Removing these AGEs may help preserve vision in people with more advanced DME.

There’s no guaranteed way to prevent diabetic macular edema. You can lower your risk with strategies like the following:

• Control blood sugar levels: Managing your blood sugar levels by following your diabetes treatment plan can help prevent damage to small blood vessels in the retina. 
• Manage blood pressure and cholesterol: High blood pressure and cholesterol can worsen blood vessel damage and increase the risk of fluid leakage in the retina.
• Get regular eye exams: Annual eye exams can help detect early signs of diabetic retinopathy and DME before symptoms develop.
• Focus on your diet and exercise routine: Eating a healthful, balanced diet and regularly exercising can help support your eye and overall health.

People with DME are more likely to have or develop other diabetes-related eye diseases. Many of these conditions share a common cause—damage to blood vessels in the eye due to prolonged high blood sugar levels.

Conditions related to DME include:

• Glaucoma: This group of eye conditions damages the optic nerve, usually due to increased eye pressure. People with diabetes are about twice as likely to develop glaucoma as those without diabetes.
• Cataracts: This clouding of the eye’s natural lens causes blurry vision. Diabetes increases the risk of cataracts at an earlier age.
• Retinal detachment: In advanced cases of diabetic retinopathy, scar tissue can pull the retina away from the back of the eye, leading to vision loss. DME-related swelling can further contribute to structural changes in the retina that increase this risk.

DME is a leading cause of vision loss in people with diabetes, but early diagnosis and treatment can help preserve vision.

Diabetic macular edema can make everyday tasks like reading, driving, or recognizing faces more difficult. Simple adjustments, like using magnifiers, increasing home lighting, and switching to larger-print materials, can help you stay independent and make everyday tasks easier.

Talk to your healthcare provider if you have diabetes and notice vision changes. With the proper care and treatment, many people with DME can maintain their vision and independence.