Diabetic retinopathy is the most common eye disease in American adults under 60, causing 85% of vision loss in this population. It is a common complication associated with diabetes, caused by deterioration of the small blood vessels in the retina. The retina is the light sensitive tissue in the eye, and a healthy retina is necessary for maintaining good vision. Two distinct stages of diabetic retinopathy, known as non–proliferative and proliferative diabetic retinopathy, can occur in poorly controlled diabetic patients.
Non–proliferative diabetic retinopathy (NPDR) is the earlier stage of diabetic eye disease. In this stage, tiny blood vessels within the retina become compromised and may develop pin point hemorrhages or leakage. This leaking fluid causes the retina to swell and is referred to as diabetic macular edema. Many people with diabetes have mild NPDR, which usually does not affect their vision. Although the changes are visible to the ophthalmologist during an eye exam, the patient may not experience any symptoms and will often retain normal vision at this stage. When vision is affected, it is often the result of macular edema or ischemia, or both. Diabetic macular edema (DME) is a condition that refers to swelling or thickening of the macula. The macula is a small area in the center of the retina that allows us to see fine details and is essential for central vision. This swelling is caused by the leaking of fluid from retinal blood vessels due to increased level of inflammation. Diabetic macular edema is the most common cause of vision loss in non–proliferative diabetic eye diseases. Laser treatment and medical treatment may reverse the damage caused by this inflammatory response.
Proliferative diabetic retinopathy (PDR) is an advanced stage of diabetic eye disease when retinal blood vessels become compromised. At this stage, the growth of new blood vessels is triggered. These new blood vessels have abnormally thin and fragile walls. Given the delicate nature of these vessels, they often break and bleed into the eye, which is referred to as vitreous hemorrhage. While a small amount of blood will only cause dark floaters, a more substantial hemorrhage may block all vision and severely affect one’s vision. As these abnormal blood vessels mature and contract, it can cause scar tissue to form and results in traction retinal detachment. Laser surgery may be used to shrink the abnormal vessels and reduce the risk of bleeding and traction. If the vitreous hemorrhage does not clear within a reasonable amount of time or if a retinal detachment is detected, a surgery called a vitrectomy can be performed. During this surgery, the eye surgeon removes the hemorrhage as well as any scar tissue that has developed. He will often perform laser treatment at the same time to minimize the risk of future blood vessel growth. Patients with PDR sometimes have minimal symptoms until late stages of this disease process takes place. Therefore, it is vital to have a regular eye exam by a trained eye professional to prevent vision loss in diabetic eye disease.
If you have diabetes, regular follow–up with your family doctor to maximize control of your blood sugar is vital. This, in conjunction with a yearly visit to your ophthalmologist, can significantly lower your risk of vision loss. Although more frequent medical eye examinations may be necessary after a diagnosis of diabetic retinopathy is made, early detection is still the best protection against vision loss in diabetic patients.
By Yu Tang “James” Su, MD