Introduction

When people think about diabetes, blood sugar readings are often the first thing that comes to mind. But diabetes can affect far more than glucose levels.

Over time, persistently high blood sugar can damage blood vessels throughout the body, including the tiny vessels that supply the retina at the back of the eye. WHO identifies permanent vision loss from damage to eye blood vessels as one of the complications diabetes can cause.

The difficulty is that early diabetic eye disease may not make your vision feel different. A person can see normally and still have changes developing in the retina.

That is why eye screening is not something to wait for until vision becomes blurry. Regular checks can identify problems earlier, when monitoring or treatment may help reduce the risk of significant vision loss.

The retina is a thin layer of light-sensitive tissue at the back of the eye. It converts light into signals that are sent to the brain, allowing you to see.

The retina depends on a network of small blood vessels for oxygen and nutrients.

When blood glucose remains elevated for long periods, these delicate vessels can become damaged. The vessel walls may weaken, leak fluid or blood, or become blocked.

As damage progresses, the retina may receive less oxygen. In more advanced disease, the eye can respond by growing abnormal new blood vessels that are fragile and prone to bleeding.

Diabetic retinopathy is an eye complication caused by diabetes-related damage to the retinal blood vessels.

HealthHub describes diabetic retinopathy as an important cause of blindness in people with diabetes and explains that damaged blood capillaries can affect the retina.

The condition can range from relatively mild changes to more advanced disease.

In early stages, small retinal blood vessels may leak fluid or blood. As the disease progresses, larger areas of the retina may lose an adequate blood supply.

In proliferative diabetic retinopathy, abnormal new blood vessels can grow on the retina. SingHealth notes that these vessels can lead to serious complications and severe vision loss.

One of the most important things to understand about diabetic retinopathy is that early disease may not noticeably affect vision.

HealthHub specifically warns that diabetic retinopathy can have no symptoms in its early stages. This means waiting until your eyesight changes can allow the disease to progress without detection.

Someone may therefore feel that eye screening is unnecessary because they can read, drive and work normally.

But screening examines the retina itself rather than relying only on how clearly you can see.

As diabetic eye disease becomes more advanced, vision changes may become noticeable.

Symptoms can include blurred or distorted vision, difficulty seeing clearly in certain areas of the visual field, or dark spots and floaters.

HealthHub notes that floaters can sometimes occur when weakened retinal blood vessels bleed into the eye.

Diabetic macular oedema can also occur when fluid leaks into the macula — the central part of the retina responsible for detailed vision. This may cause central vision to become blurry or distorted.

Advanced diabetic retinopathy can result in substantial vision impairment or even permanent vision loss.

Anyone with diabetes can develop diabetic retinopathy, but the risk is not identical for everyone.

The longer someone has diabetes, the greater the opportunity for blood-vessel damage to develop.

Persistently high blood sugar increases risk, which makes long-term glucose management important.

High blood pressure and abnormal cholesterol can also contribute to blood-vessel damage and may increase the risk of diabetic eye complications.

Pregnancy can require closer eye monitoring in women who already have diabetes because retinal changes can sometimes progress more rapidly during pregnancy.

Kidney disease and other diabetes-related complications may also indicate a higher overall burden of small blood-vessel damage.

Regular retinal screening allows diabetic retinopathy to be identified before symptoms become obvious.

HealthHub describes diabetic retinal photography as a screening test designed to help prevent blindness caused by diabetic retinopathy.

During retinal photography, images of the retina are taken and assessed for signs of damage such as bleeding or other abnormalities.

Singapore also has the Singapore Integrated Diabetic Retinopathy Programme, or SiDRP. The programme uses retinal photographs and a centralised team of trained readers to assess patients for diabetic retinopathy.

The appropriate screening interval depends on your diabetes type, previous eye findings and individual risk, so follow the schedule recommended by your healthcare team.

Treatment depends on how advanced the disease is and whether complications such as macular swelling or abnormal new blood vessels are present.

Some people with early changes may only need careful monitoring together with better control of diabetes and cardiovascular risk factors.

When diabetic macular oedema affects vision, medicines known as anti-VEGF agents may be injected into the eye to reduce abnormal blood-vessel activity and swelling.

In more advanced proliferative diabetic retinopathy, SingHealth notes that laser treatment known as panretinal photocoagulation may be used to reduce the growth of abnormal new blood vessels and lower the risk of severe vision loss.

Surgery may sometimes be required when serious complications such as significant bleeding or retinal detachment occur.

Protecting vision begins with good overall diabetes management.

Keep blood glucose within the personalised targets recommended by your healthcare team. Long-term glucose control can help reduce the risk of diabetes-related blood-vessel complications.

Blood pressure management is also important because hypertension can add further stress to small blood vessels.

Follow prescribed treatment for cholesterol and other cardiovascular risk factors when appropriate.

Avoid smoking, stay physically active and follow a balanced eating pattern that supports diabetes management and overall cardiovascular health.

Most importantly, continue retinal screening even when your vision seems normal.

Can Blood Sugar Cause Temporary Blurred Vision?

Changes in blood glucose can sometimes temporarily affect how the eye focuses, causing blurred vision even without diabetic retinopathy.

This can happen when changes in glucose levels alter fluid balance within parts of the eye.

However, do not assume recurring blurred vision is simply a temporary blood-sugar effect. People with diabetes can also develop diabetic retinopathy, cataracts and other eye conditions.

Persistent or unexplained vision changes should therefore be assessed appropriately.

Does Better Blood Sugar Control Reverse Diabetic Retinopathy?

Improving diabetes control is important for reducing the risk of further blood-vessel damage, but it should not be viewed as a guaranteed way to reverse established retinal disease.

Once diabetic retinopathy is present, the eyes may still require ongoing monitoring or specific treatment.

This is why glucose management and ophthalmic care work together rather than replacing one another.

Why You Should Not Wait for Your Eyesight to Get Worse

It is easy to assume that an eye problem should produce an obvious visual symptom.

Diabetic retinopathy is different because early retinal damage can progress quietly.

By attending recommended screening, problems can potentially be identified before they reach a stage where vision is significantly affected.

For someone living with diabetes, protecting eyesight is therefore an ongoing part of diabetes care — not something to consider only after vision changes.