Diabetic Macular Edema
Swelling of the central retina that blurs vision in diabetes
Quick Facts
- Type: Eye (retinal) complication of diabetes
- Affected area: The macula (center of the retina)
- Main symptom: Blurred or distorted central vision
- Key step: Regular dilated eye exams
Overview
The macula is the small central part of the retina at the back of the eye that gives sharp, detailed vision for reading, recognizing faces, and seeing fine detail. Diabetic macular edema (DME) is swelling of the macula caused by fluid leaking from damaged blood vessels in the retina. It is a leading cause of vision loss in people with diabetes.
DME develops as a result of diabetic retinopathy, the damage that high blood sugar causes to the tiny blood vessels of the retina over time. As these vessels weaken, they can leak fluid and proteins into the macula, causing it to swell and thicken. Because the macula handles central vision, this swelling can blur or distort what a person sees. DME can occur at any stage of diabetic retinopathy and may affect one or both eyes.
Symptoms
Early DME may cause no symptoms, which is why regular eye exams are so important. As swelling increases, symptoms can include:
- Blurred or hazy central vision
- Difficulty reading or seeing fine detail
- Colors appearing washed out or faded
- Straight lines that look wavy or distorted
- A dark or empty spot in the center of vision
- Increased difficulty with tasks such as driving or recognizing faces
Side (peripheral) vision is usually not affected. Any new blurring, distortion, or central vision change in a person with diabetes should be checked promptly by an eye specialist.
Causes
DME is caused by the effects of diabetes on the retina's blood vessels:
- High blood sugar over time: Damages the walls of the small retinal vessels, making them leaky.
- Leaking fluid and proteins: Seep into the macula and cause it to swell.
- Abnormal signaling proteins: A substance called vascular endothelial growth factor (VEGF) increases vessel leakiness and is a key target of treatment.
Poorly controlled blood sugar, high blood pressure, and high cholesterol all worsen the vessel damage that leads to DME.
Risk Factors
- Longer duration of diabetes
- Poorly controlled blood sugar (high A1C)
- High blood pressure
- High cholesterol
- Kidney disease related to diabetes
- Pregnancy in women with diabetes
- More advanced diabetic retinopathy
Diagnosis
An eye doctor diagnoses DME during a dilated eye exam using specialized imaging:
- Dilated eye exam: Drops widen the pupil so the retina and macula can be examined.
- Optical coherence tomography (OCT): A scan that produces detailed cross-section images of the retina and measures macular thickness and fluid.
- Fluorescein angiography: A dye injected into a vein highlights leaking blood vessels in the retina.
- Visual acuity testing: Measures how clearly the central vision is working.
Treatment
Treatment aims to reduce swelling, preserve vision, and control the diabetes driving the disease. An eye specialist guides care.
- Anti-VEGF injections: Medicines injected into the eye that reduce vessel leakage and swelling; these are a mainstay of treatment and are given on a repeated schedule.
- Corticosteroid treatment: Steroid injections or implants in the eye can reduce inflammation and swelling in some cases.
- Laser treatment: Focused laser can seal leaking vessels in selected situations.
- Managing diabetes: Controlling blood sugar, blood pressure, and cholesterol slows the underlying disease and supports treatment.
Many people maintain or improve their vision with ongoing treatment, but follow-up is needed because DME can recur.
Prevention
- Keep blood sugar within your target range
- Control blood pressure and cholesterol
- Have a dilated eye exam at least once a year, or as often as your eye doctor advises
- Do not smoke
- Report any change in vision promptly rather than waiting for the next routine exam
- Take diabetes and other medicines as prescribed
When to See a Doctor
Anyone with diabetes should have regular dilated eye exams even without symptoms. Contact an eye doctor promptly if you notice:
- New or worsening blurred central vision
- Straight lines that appear wavy or bent
- A dark or blank spot in the center of your sight
- Faded or washed-out colors
A sudden curtain or shower of new floaters, flashes of light, or sudden major vision loss may signal a different, urgent retinal problem and needs prompt evaluation.
Frequently Asked Questions
What is diabetic macular edema?
It is swelling of the macula, the central part of the retina, caused by fluid leaking from damaged retinal blood vessels in people with diabetes. Because the macula handles sharp central vision, this swelling blurs or distorts vision.
What are the symptoms of DME?
Common symptoms include blurred or hazy central vision, trouble reading, faded colors, straight lines that look wavy, and a dark spot in the center of vision. Early DME may have no symptoms, so regular eye exams are important.
How is diabetic macular edema treated?
The main treatment is anti-VEGF injections into the eye to reduce leakage and swelling. Steroid treatments and laser therapy are used in some cases, along with good control of blood sugar, blood pressure, and cholesterol.
Can diabetic macular edema be prevented?
You can lower the risk by keeping blood sugar, blood pressure, and cholesterol well controlled, not smoking, and having regular dilated eye exams. Early detection and treatment help protect vision.
Will vision come back after treatment?
Many people keep or regain vision with ongoing treatment, especially when DME is caught early. Results vary, and because the swelling can return, regular follow-up with an eye specialist is needed.
References
- National Eye Institute (NEI). Diabetic retinopathy and macular edema.
- American Academy of Ophthalmology. Diabetic macular edema.
- Centers for Disease Control and Prevention (CDC). Diabetes and vision loss.
- MedlinePlus, U.S. National Library of Medicine. Diabetic eye problems.