Diabetes and the Eye

What Is Diabetic Retinopathy?

Diabetes is very common in our society and is the most common cause of blindness after age 50. The damage diabetes causes to the eye's nerve layer, the retina, is called diabetic retinopathy.

How Does Diabetes Affect the Eye?

Diabetes causes blockage of the tiny blood vessels in the retina and leakage of fluid from these vessels. The blockage of these vessels leads to the formation of abnormal new blood vessels that bleed easily. The blockage of the capillaries, the leakage of fluid, and the bleeding from these abnormal vessels cause serious problems in the eye.

Why Does Vision Decrease in Diabetes?

The main sign of diabetes in the eye is vision loss. The most common cause of vision loss is fluid accumulation and swelling (edema) in the macula. In addition, bleeding from abnormal blood vessels and retinal tears can cause sudden vision loss.

Cataract is more common in diabetic patients than in others and develops at an earlier age. Untreated patients can develop glaucoma, which not only causes vision loss but also serious pain.

In some diabetic patients, vision is not affected even though their blood sugar is very high. In others, vision loss develops even though their blood sugar is close to normal. We do not know the reason for this discrepancy either. For this reason, it is not correct to think, “my neighbor's blood sugar was 500, and nothing happened to him, so nothing will happen to me.” Every diabetic patient is at risk, even if their blood sugar is normal.

How Is Diabetic Retinopathy Treated?

The real goal should not be reducing the effects of diabetes on the eye, but preventing diabetes from affecting the eye in the first place. For this, blood sugar levels must be monitored very strictly and regularly. Sudden spikes and sudden drops should be avoided, as they increase nerve damage in the eye. In addition, high blood pressure, abnormal cholesterol levels, and poorly functioning kidneys increase the effect of diabetes on the eye. Care should be taken with these factors as well.

The primary cause of diabetes-related vision loss is macular edema. Injection treatment is given into the eye to correct the edema. In this treatment, the eye is initially injected 3 times, one month apart. Additional injections can be given during later follow-up if needed.

Laser treatment is applied when abnormal new blood vessels form. Otherwise, the bleeding and retinal tears caused by these vessels lead to serious vision loss. When bleeding or a retinal tear develops, retinal surgery is performed.

When Should Diabetic Patients Have Eye Exams?

A patient diagnosed with diabetes should have an eye exam immediately. This is because the person may have been unaware of their diabetes for many years, and bleeding may have already started in their eye. Good vision in a patient does not mean that diabetes has not affected the eye. Vision is not affected as long as the bleeding does not involve the macula, even though bleeding may already have started in other areas of the retina.

If the first exam shows that diabetes has not affected the eye, subsequent exams are done once a year. However, patients with type 1 diabetes, those who have had diabetes for many years, those with poorly controlled blood sugar, and those who already have bleeding in the eye should be examined more frequently. For these patients, the exam schedule is set by the physician.