By David A. Quillen, M.D.
Diabetes mellitus affects nearly 26 million people in the United States. It is the leading cause of new blindness among adults between 20 and 74 years of age with 12,000 to 24,000 new cases of blindness occurring each year. The statistics are alarming: Individuals with diabetes are 25 times more likely than the general population to become blind. Fortunately, there is good news in the fight against blindness from diabetes. Early detection combined with appropriate general medical and eye care can significantly reduce the risk of vision loss related to diabetes.
Diabetic retinopathy is the leading cause of vision loss in individuals with diabetes. Diabetic retinopathy is divided into two categories: nonproliferative and proliferative. Nonproliferative diabetic retinopathy is characterized by abnormalities of the retina including microaneurysms, intraretinal hemorrhages, cotton wool spots, macular edema, and lipid exudates. The most common cause of vision loss in nonproliferative diabetic retinopathy is macular edema. Proliferative diabetic retinopathy is characterized by the proliferation of blood vessels as a result of widespread circulation abnormalities within the retina. These abnormal blood vessels may result in severe hemorrhages and scar tissue formation within the eye.
It is important to recognize that diabetic retinopathy does not occur in isolation but is affected by the overall general medical status of the person with diabetes. The onset and severity of diabetic retinopathy is influenced by many factors including the duration of diabetes, the quality of diabetes control, hypertension, lipid abnormalities, kidney disease, and fluid overload states (e.g., congestive heart failure). Improvement in the control of these factors may be associated with a substantial reduction in the risk of vision loss from diabetic retinopathy.
Individuals with diabetic retinopathy may not experience symptoms of vision loss. Because of this, it is critical that regular comprehensive eye examinations are performed to promote early detection and treatment. The American Academy of Ophthalmology (AAO) has established a recommended eye examination schedule for individuals with diabetes. For those with type 1 diabetes (diabetes usually diagnosed before the age of 30), the AAO recommends that a comprehensive eye examination be performed annually beginning three to five years after the diagnosis of diabetes. This reflects the low incidence of significant diabetic retinopathy in individuals with less than five years of diabetes.
The time of onset of type 2 diabetes is difficult to determine precisely. As a result, significant diabetic retinopathy may be observed in individuals with type 2 diabetes at the time of diagnosis or shortly thereafter. The AAO recommends that a comprehensive eye examination be performed at the time of diagnosis in patients with type 2 diabetes. Because diabetic retinopathy may progress during pregnancy, eye examinations should be performed prior to conception or early in the first trimester of pregnancy.
When diabetic retinopathy occurs, surgical options are available—but early detection is key! Laser photocoagulation and intraocular medications have proven to reduce the risk of vision loss for diabetic macular edema and proliferative diabetic retinopathy.
Several studies have confirmed the benefit of intensive diabetes management in reducing the development and progression of diabetic retinopathy. Therefore, the most important thing people with diabetes can do to reduce the risk of vision loss related to diabetic retinopathy is to control their blood glucose levels and address associated medical problems such as high blood pressure and lipid abnormalities.
David A. Quillen, M.D., is the George and Barbara Blankenship Professor and chair, Department of Ophthalmology, Penn State Hershey Medical Center and Penn State College of Medicine, and director, Penn State Hershey Eye Center.