Diabetic Retinopathy

How diabetic retinopathy damages the eye

The retina needs a steady supply of oxygen from tiny blood vessels. Years of high blood sugar weaken these vessel walls. They develop small bulges (microaneurysms), leak fluid and fats, and bleed in tiny dots. Some vessels close off, starving parts of the retina of oxygen.

The starved retina releases a growth signal called VEGF (vascular endothelial growth factor). VEGF makes fragile new vessels sprout on the surface of the retina. These vessels bleed easily and form scar tissue that can pull the retina away from the back of the eye. VEGF also makes vessels leakier, causing swelling of the central retina.

Stages of diabetic retinopathy

Diabetic macular edema (DME) can occur at any stage. Fluid leaks into the macula, the central part of the retina used for reading and recognizing faces, and is the most common cause of vision loss from diabetes. See diabetic macular edema.

Symptoms

Early retinopathy is silent: you can have significant damage with perfect vision. When symptoms appear, they include:

• Blurred vision, especially for reading
• Wavy or distorted central vision (from macular edema)
• New floaters, cobweb-like strands or dark spots
• A sudden red or dark haze after a bleed into the vitreous gel
• Patchy or missing areas of vision
• Poor night vision and faded colors

Blurring that comes and goes over days can also be caused by swings in blood sugar changing the shape of the lens, not retinopathy. It still deserves an eye exam.

Risk factors

• Diabetes duration: after 20 years, most people with type 1 and many with type 2 diabetes have some retinopathy.
• Blood sugar control: higher A1C raises risk. Each lowering of A1C reduces it.
• High blood pressure and high cholesterol
• Kidney disease (diabetic nephropathy)
• Pregnancy, which can speed up retinopathy
• Smoking
• Rapid improvement in blood sugar after years of poor control can temporarily worsen retinopathy, so an eye check is advised when starting intensive treatment, including some GLP-1 medicines, if retinopathy is already present

Screening: how often you need an eye exam

Because early disease has no symptoms, regular screening is the most important protection.

Gestational diabetes alone does not need these extra checks.

How it is diagnosed

• Dilated eye exam: drops widen the pupils so an eye doctor can see the whole retina. Vision is blurry and light-sensitive for a few hours afterwards, so bring sunglasses and avoid driving.
• Retinal photographs: used in screening programs and some primary care clinics, sometimes with AI-assisted reading.
• Optical coherence tomography (OCT): a painless scan that measures retinal thickness and detects macular edema.
• Fluorescein angiography: dye injected into an arm vein shows leaking or closed vessels.

Treatment for diabetic retinopathy

Controlling diabetes, blood pressure and cholesterol

This is the foundation at every stage. Good control slows progression and makes other treatments work better. Typical targets are an A1C around 7% or lower if safe for you, and blood pressure below 130/80 mm Hg. Fenofibrate, a cholesterol medicine, may slow progression in some people with type 2 diabetes.

Anti-VEGF injections

Medicines such as aflibercept, ranibizumab, bevacizumab and faricimab block VEGF. They are injected into the eye after numbing drops, usually monthly at first and then less often. They are first-line for macular edema affecting central vision, and are also used for proliferative disease. Many people's vision improves.

Laser treatment

• Panretinal photocoagulation (PRP): hundreds of tiny laser burns across the outer retina reduce VEGF production and make new vessels shrink. It cuts the risk of severe vision loss in proliferative disease by more than half, but can reduce side and night vision.
• Focal or grid laser: seals specific leaking vessels in some cases of macular edema.

Steroid implants

Long-acting steroid implants placed in the eye are an option for macular edema that does not respond to anti-VEGF. They can cause cataract and raise eye pressure.

Vitrectomy surgery

Used when blood in the vitreous gel does not clear on its own, or when scar tissue pulls on the retina. The surgeon removes the gel and blood, peels away scar tissue and applies laser.

Complications

• Vitreous hemorrhage: a bleed into the gel that fills the eye, causing sudden floaters or loss of vision. See vitreous hemorrhage.
• Tractional retinal detachment: scar tissue pulls the retina off the back of the eye.
• Neovascular glaucoma: new vessels block fluid drainage, raising eye pressure painfully.
• Permanent vision loss, now preventable in most cases with timely treatment.

People with diabetes also develop cataracts earlier.

Outlook

With regular screening and timely treatment, the risk of severe vision loss from diabetic retinopathy falls dramatically: the National Eye Institute estimates by about 95%. Damage already done is often only partly reversible, so the goal is to find and treat changes before vision is affected. Anti-VEGF injections can improve vision lost to macular edema, but they need ongoing visits.

Preventing diabetic retinopathy

• Keep A1C, blood pressure and cholesterol in your target ranges.
• Do not smoke.
• Get a dilated eye exam or retinal photographs every year, or as advised.
• Plan pregnancy and get an eye exam before or early in pregnancy.
• Report any vision change promptly instead of waiting for your next scheduled check.

Frequently asked questions

What are the first signs of diabetic retinopathy?

There are usually no early signs you can notice. The first changes, tiny bulges and bleeds in retinal vessels, are seen only on an eye exam. When symptoms appear, they are typically blurred reading vision, floaters or dark spots, which often means the disease is already moderate or advanced.

Can diabetic retinopathy be reversed?

Early, mild changes can stabilize and sometimes improve with better blood sugar and blood pressure control. Macular swelling often improves with anti-VEGF injections. Advanced damage such as scarring or long-standing vision loss usually cannot be fully reversed, which is why early detection matters.

How long does it take to develop diabetic retinopathy?

It usually appears after several years of diabetes. In type 1 diabetes it is rare in the first 5 years. In type 2 diabetes, some people already have retinopathy at diagnosis because blood sugar may have been high for years beforehand.

Do the eye injections hurt?

Most people feel pressure rather than pain. The eye is numbed with drops or gel, cleaned, and held open with a small clip. The injection takes a few seconds. The eye can feel gritty for a day, and a small red patch on the white of the eye is common and harmless.

What is the difference between proliferative and non-proliferative diabetic retinopathy?

In non-proliferative retinopathy, damaged vessels leak and bleed but no new vessels grow. In proliferative retinopathy, the oxygen-starved retina triggers abnormal new vessels that can bleed and form scar tissue, risking sudden vision loss. Proliferative disease needs prompt laser or injection treatment.

Can I drive with diabetic retinopathy?

Many people can, as long as their vision meets the legal standard in both clarity and field of vision. Extensive laser treatment can reduce side vision. Your eye doctor can tell you whether your vision meets your state's driving requirements.