Diabetic Retinopathy Guide: When High Blood Sugar Damages the Eyes

diabetic risk to the eyesDiabetic retinopathy is an eye disease that is a complication of diabetes. In diabetes, levels of blood sugar are chronically elevated due to lack of insulin, an insulin  insensitivity, or a combination of both. Just as sugar combined with water outside the body forms a sticky substance, excessive sugar in the bloodstream does so as well. Sugar adheres to numerous different tissues in the body, causing problems depending on the tissue. Prolonged excessive sugar in the bloodstream tends to damage the blood vessels of the retina, the back part of the eye that sends light signals to the brain. As the blood vessels become increasingly damaged, the risk of vision loss grows higher and higher.

It is estimated that between 40-45% of all people diagnosed with diabetes have some degree of retinopathy. And up to 80% of people who have had diabetes for ten years or more suffer from some degree of retinopathy. It is the leading cause of blindness in people between the ages of 20 and 64. Fortunately, most cases of diabetic retinopathy can be well controlled if caught and treated early.

The first line of defense in preventing retinopathy is to tightly control blood sugar levels. Tightly controlled blood sugar significantly delays both the onset and the progress of retinopathy. Unfortunately, because retinopathy is frequently asymptomatic until very late in the disease, people may be unaware that they have it. That is why it is very important to get a yearly eye exam with dilation.

Stages of Retinopathy

Retinopathy is characterized by increasing problems with the blood vessels that supply the retina. At first, the walls of the blood vessels become thin and increasingly fragile. This leads to small balloon-like swellings called microaneurysms. This is mild nonproliferative retinopathy. Next, some of the blood vessels that feed the retina become blocked. This is moderate nonproliferative neuropathy. Third, blockages continue to spread until parts of the retina have no blood supply at all. This is severe nonproliferative retinopathy. Finally, the retina signals the body to begin making new blood vessels in an attempt to restore blood supply. The body does so, but the new blood vessels are very thin and fragile and can burst easily. This last stage is called proliferative retinopathy.

Vision Loss

Vision loss occurs for two reasons. First, at any stage of retinopathy, blood vessels can leak fluid into the retina, blurring vision. If enough fluid leaks, the center of the retina, known as the macula, can swell. This is called macular edema. It causes straight-ahead vision to become blurry and/or holes appear in the visual field. Milder symptoms of retinopathy include having floaters in the visual field and having trouble seeing at night.

Risk Factors

Diabetes is the primary risk factor for retinopathy. Both Type I and Type II diabetes are risk factors. Hispanics and African-Americans show a higher prevalence than other races. Comorbid conditions that damage blood vessels also increase risk, particularly high blood pressure and elevated cholesterol. Pregnancy can be a risk due to gestational diabetes, which is also a risk factor for the later development of diabetes.


Diabetic retinopathy is diagnosed with a personal history, a visual acuity test, and a dilated eye exam. With dilation, the eye doctor can view the retina of the eye and the blood vessels and see any changes taking place. Signs of retinopathy include leaking blood vessels, swelling of the retina, fatty deposits on the retina, damaged nerve tissue and changes in the structure of the blood vessels. Tonometry may also be used to measure pressure in the eye, which can also increase retinopathy.


Early diabetic retinopathy may require no treatment other than regular monitoring. Efforts to regulate blood sugar and get regular exercise can also slow disease progression. If the blood vessels show signs of deterioration or leakage, a laser may be used to create small burns in the retina to encourage the blood vessels to heal. Hundreds of small burns are made on the retina. If substantial fluid leaks into the macula, a more serious laser procedure may be needed to cause abnormal blood vessels to shrink and/or disappear. Thousands of tiny laser burns are made on the retina. Because of the intensity of the procedure, two sessions may be necessary to complete the treatment. In this instance, people may experience some loss of side vision but their central vision will be better preserved.

If the vitreous, the clear, gel-like center of the eye that sits in front of the retina has too much blood and fluid in it, a vitrectomy may be needed. This is a procedure that removes the clouded vitreous and replaces it with saline fluid to retain the shape of the back of the eye. Because the vitreous is made up of mostly fluid, people usually do not notice a difference between the vitreous and its replacement.

Newer drug therapies are also being developed. The current recommendation for macular edema is to also treat the conditions with an anti-VEGF (vascular endothelial growth factor) which deters new blood vessel formation. Research is being done on C-peptide, a byproduct of insulin manufacture that shows promise in treating many diabetes-related problems.

Experimental Treatments

A small study has shown that Pycnogenol, a pine bark extract, improved some measures of eye deterioration in the early stages of retinopathy. Shark or bovine cartilage might also prove helpful as cartilage contains naturally occurring factors that inhibit the formation of new blood vessels.

General Health Considerations

As in many chronic systemic diseases, proper health maintenance can go a long way toward preventing or delaying serious disease complications. Many people with diabetes do not have sufficient education on the long-term effects of poor blood sugar management. Type II diabetes can usually be greatly controlled with lifestyle measures such as diet, exercise and proper supplementation. All diabetics should receive regular eye exams with dilation from an ophthalmologist. An ounce of prevention is worth a pound of cure.