Diabetes and Your Eyes: Understanding Diabetic Retinopathy

By the Royal Eye & Ear Hospital Ophthalmology Team · 6 min read

If you live with diabetes, you probably check your blood sugar, watch your diet and take your medication. But when did you last have your eyes checked?

Diabetes doesn’t only affect your blood sugar. Over time, high sugar levels damage the tiny blood vessels throughout your body, including the delicate vessels in the retina, the light-sensitive layer at the back of your eye. This damage is called diabetic retinopathy, and it is one of the most common causes of vision loss in working-age adults worldwide.

Like glaucoma, it often develops without any warning signs. By the time your vision becomes blurry, the disease may already be advanced. The good news: with regular eye checks and early treatment, most serious vision loss from diabetes can be prevented.

How diabetes damages the eye

Think of the retina as the film in a camera. It needs a steady supply of blood through very fine vessels. When blood sugar stays high for long periods, those vessels become weak and leaky. They may:

• Leak fluid or blood into the retina, causing swelling and blurry vision
• Close off, starving parts of the retina of oxygen
• Grow new, abnormal vessels that bleed easily and can cause scarring or retinal detachment

The stages of diabetic retinopathy

Notice that the first two stages often have no symptoms. This is exactly why waiting for problems is risky: these are also the stages when treatment works best.

Are you at risk?

If you have diabetes, you are at risk. Your chances are higher if you:

• Have had diabetes for many years. Risk increases the longer you live with it.
• Have poorly controlled blood sugar, shown by a high HbA1c result.
• Have high blood pressure or high cholesterol, which add further stress to blood vessels.
• Miss doses or stop medication. Treatment compliance is strongly linked to eye damage.
• Are pregnant and have diabetes, as retinopathy can progress quickly during pregnancy.
• Smoke, which damages blood vessels further.

Warning signs to watch for

In later stages you may notice:

• Blurred or fluctuating vision
• Dark spots, strings or “floaters” drifting across your vision
• Dark or empty areas in your field of view
• Colours appearing faded or washed out
• Difficulty seeing at night

How we check your eyes

A diabetic eye examination is painless. At Royal Eye & Ear Hospital, it typically includes:

• Visual acuity test. Reading letters on a chart to measure how clearly you see.
• Dilated eye examination. Drops widen your pupils so the doctor can see the whole retina. Your vision may be blurry and light-sensitive for a few hours, so bring sunglasses and consider arranging a driver.
• Retinal photography. Detailed photos of the back of the eye. Research in Kenya found photographs pick up early retinopathy that can be missed on examination alone.
• OCT scan. A quick, non-contact scan that shows swelling in the macula.

Treatment options

Early-stage retinopathy may only need closer monitoring and better control of your diabetes. When treatment is needed, options include:

• Anti-VEGF injections. Medicine injected into the eye to reduce swelling and stop abnormal vessels growing. The eye is numbed first, and the procedure takes only minutes.
• Laser treatment. Seals leaking vessels and shrinks abnormal ones to lower the risk of bleeding.
• Vitrectomy surgery. For advanced cases with bleeding or scar tissue, this removes blood from inside the eye and repairs the retina.

Treatment works best before vision is badly affected, which is why routine screening is so important.

Seven ways to protect your eyes with diabetes

• Have a dilated eye exam every year, even if your vision seems perfect.
• Keep your blood sugar within your target range and know your HbA1c number.
• Control your blood pressure and cholesterol.
• Take your medication exactly as prescribed. Don’t skip doses.
• Stay active and eat a balanced diet with plenty of vegetables and whole grains.
• Stop smoking.
• Tell your eye doctor if you are pregnant or planning a pregnancy.

Myths vs facts

Frequently asked questions

This article is for general information only and does not replace a consultation with a qualified eye specialist or your diabetes care team. If you have concerns about your vision, please book an appointment.