Diabetic Retinopathy

Diabetes Mellitus and Your Vision

Diabetes mellitus effects fourteen million Americans. Twenty-five percent of diabetics have some form of diabetic retinopathy. Diabetic retinopathy accounts for twenty percent of new cases of blindness in the United States between the ages of forty-five and seventy-four. Blindness is twenty-five times more common in diabetics than in nondiabetics. However, proper management of diabetes and its ocular complications can reduce the risk of blindness by ninety percent. It is important to take an active role in controlling this disease. The information below can help you understand more about diabetes and what you can do to prevent its complications.

Diabetes Mellitus: The Disease

There are two main types of diabetic retinopathy. The first type is called Type I or insulin-dependent diabetes mellitus. This type typically starts at a young age and requires insulin for treatment. Insulin is a substance that the pancreas produces to lower blood glucose levels.

The second type is called Type II or non-insulin-dependent diabetes mellitus. People affected by this type are usually over the age of forty. Type II is often controlled with diet alone or diet and oral medications that lower the glucose level. High levels of glucose in the blood can damage many organ systems, including the eye. The cause of diabetes mellitus is not completely known. Genetic, environmental, autoimmune and infectious components may play a role in its development.

Diabetic Eye Disease

Diabetes can affect vision in many ways. High glucose levels can cause a temporary change in the shape of the lens. The lens is the structure that focuses light on the retina. The temporary change in shape of the lens can cause a diabetic's vision to fluctuate. Cataract formation is another common cause of visual impairment in diabetic patients. Cataracts are opacities that develop in the normally clear lens.

Twenty percent of patients will develop diabetic retinopathy. The retina is a layer of cells in the back of the eye. It functions like the film in a camera to capture what you are seeing so that it can be transmitted to the brain. There are two main types of diabetic retinopathy. The first is called background or nonproliferative diabetic retinopathy. In this type of diabetic retinopathy, the blood vessels in the retina leak and hemorrhage. The patient may notice a decrease in vision if the swelling and hemorrhage affect a portion of the retina called the macula. The macula is responsible for central vision. Macular edema or swelling is the most common cause of visual loss in diabetic retinopathy. The second type of diabetic retinopathy is called proliferative diabetic retinopathy. In this condition, new blood vessels grow in the eye. These new blood vessels tend to bleed and leak causing vision loss. These new blood vessels may also pull on the retina causing a retinal detachment. The patient may not have any symptoms but still have diabetic eye disease that can be easily seen by an ophthalmologist. It is important to get regular screening examinations to diagnose and treat the vision threatening complications of diabetes.

Figure 1
Figure 1: Anatomy of eye


Figure 2
Figure 2: Fundus photo of normal macula


Figure 3
Figure 3: Hemorrhages in non-proliferative diabetic retinopathy


Figure 4
Figure 4: New blood vessel growth around optic nerve in proliferative diabetic retinopathy


Figure 5
Figure 5: Hemorrhage from new blood vessel growth in proliferative diabetic retinopathy

Prevention of Diabetic Eye Disease

The severity of diabetic eye disease is associated with blood glucose levels. A major study showed that control of blood glucose reduces the risk and delays the progression of diabetic retinopathy. It is important to work with a primary care physician to establish and follow an appropriate treatment plan, including diet and exercise, to control blood glucose levels.

Treatment of Diabetic Eye Disease

A patient should be examined by an ophthalmologist within five years of the initial diagnosis of diabetes if he/she is younger than thirty years old. After the age of thirty, the first recommended eye examination is at the time of diagnosis. The routine minimum follow-up is on a yearly basis. However, your ophthalmologist may want to evaluate at earlier intervals depending on the severity of the diabetic eye disease. It is important to have an eye examination at the start of a pregnancy and then at every three months because pregnancy may worsen diabetic eye disease.

Laser treatment of leaking blood vessels (focal laser) for macular edema reduces the risk of future vision loss by 50%. Laser treatment to the Peripheral retina (pan-retinal photocoagulation) is used for proliferative diabetic retinopathy. It causes the abnormal new blood vessels to stop growing and shrink. This type of laser treatment can reduce the risk of severe visual loss by 50%.

Some patients may benefit from the injection of pharmacological agents into the vitreous cavity. This includes the use of anti-VEGF agents as well as corticosteroids. Studies are being done to assess the efficacy of these treatment modalities specifically for macular edema associated with diabetic retinopathy.

Vitrectomy is an operation to treat retinal detachment and hemorrhage caused by diabetes. The vitreous is a substance that helps give the eye its shape. A vitrectomy is performed by a retinal surgeon to remove the blood in the vitreous and also to reattach the retina.

Cataract surgery is an extremely successful operation to remove the cataractous lens and implant a clear lens. Early detection and treatment of diabetic eye disease has a major impact on the incidence of blindness. Early diabetic eye disease initially may have no symptoms. It is important to have an initial eye examination with an ophthalmologist and keep regularly scheduled appointments. Proper management of the diabetes can help prevent the devastating complication of blindness.