According to the National Eye Institute, diabetes is the leading cause of blindness in adults in the United States. The disease can lead to several eye complications, the most common being cataracts and diabetic retinopathy.
Frequent changes in blood sugar levels can cause a cataract, a clouding of the eye’s lens that blocks light. Diabetic retinopathy occurs when high blood sugar levels damage the blood vessels in the retina, the light-sensitive tissue at the back of the eye. The damaged retina can lead to blurred vision and even blindness.
“The severity of diabetic retinopathy can be limited or prevented by the control of blood sugars, blood pressure and lipids,” says George Clavenna, D.O., ophthalmologist at Des Moines University Clinic. “If you keep blood sugar below 150 all the time, you can decrease the risk of developing the disease by 78%, or decrease the chance of severe vision loss by 50% if you already have it, according to the Diabetes and Complications Trial.”
There are two basic stages of diabetic retinopathy. Nonproliferative diabetic retinopathy (NPDR) is the early stage and may have no symptoms at all. But as the disease progresses, blood vessels may leak fluid or blood, causing vision loss. Small areas of balloon-like swelling in the blood vessels called microaneurysms can also develop and leak, producing hemorrhages.
At the advanced stage, known as proliferative diabetic retinopathy (PDR), a substance sent by the retina for nourishment triggers the growth of new blood vessels. These new blood vessels are abnormal and fragile. When they leak, they produce vitreous hemorrhages that appear like cobwebs or blocked out vision. They may also contract, causing traction retinal detachment, severe vision loss or blindness.
The longer you have diabetes and the more uncontrolled you are, the more likely you are to develop diabetic retinopathy. Type 1 diabetics generally will not see any signs of diabetic retinopathy for at least five years. However, the bulk of diabetic adults have type 2 and may have gone undiagnosed for years. They are more likely to have developed diabetic retinopathy by the time of diagnosis.
“If you’re diagnosed with diabetes, you should be seen by an eye care practitioner immediately,” advises Clavenna. “If you need treatment for diabetic retinopathy, you need to see an ophthalmologist.”