One of the most frequent causes of vision impairment in the United States and throughout the rest of the world is diabetic retinopathy. Diabetic retinopathy is a complication of diabetes that causes damage to the blood vessels of the retina—the light-sensitive tissue that lines the back part of the eye, allowing you to see fine detail.
The longer someone has diabetes, and the less his or her blood sugars are controlled, the more likely the possibility that person will develop diabetic retinopathy.
There are generally 2 causes of vision loss from diabetic retinopathy: diabetic macular edema and proliferative diabetic retinopathy.
DIABETIC MACULAR EDEMA
Diabetic macular edema is the term used for swelling in the central part of the retina. The macula—or center part—of the retina is used for sharp, straight-ahead vision. It is nourished by blood vessels that are weakened or begin to leak as a result of diabetes. This causes the central part of the retina to become thickened or swollen and can lead to decreased vision.
PROLIFERATIVE DIABETIC RETINOPATHY
Diabetes can cause damage to the small blood vessels in the retina, resulting in poor circulation to the retina. Vision may be lost because some of the retina tissue may die as a result of this inadequate blood supply. Unlike skin tissue, which might grow back if it is lost, retina tissue is like brain tissue and does not grow back once it is lost.
Poor circulation associated with diabetes may lead to the development of growth factors that can cause new blood vessels and scar tissue to grow on the surface of the retina. This stage of diabetic retinopathy referred to as “proliferative” because at this stage of the disease, new, abnormal blood vessels and scar tissue begin to grow on the surface of the retina. The vessels bleed into the middle cavity of the eye, causing vision loss because light cannot reach the retina. Scar tissue formation can also pull on the retina, detaching it from the back of the eye, resulting in vision loss.
Symptoms
It is possible to have diabetic retinopathy for a long time without noticing symptoms until substantial damage has occurred.
• Blurred or double vision
• Difficulty reading
• The appearance of spots—known as “floaters”
• Shadow across the field of vision
• Eye pain or pressure
• Difficulty with color perception
• Some patients may experience a partial or total loss of vision
It is important to note that diabetic retinopathy usually affects both eyes.
Causes
The primary cause of diabetic retinopathy is diabetes—a condition in which the levels of glucose (sugar) in the blood are too high. Diabetes can damage the small blood vessels that nourish the retina and may in some cases block them completely. The blood supply to the retina from these damaged blood vessels is cut off and vision is affected.
Risk factors
• Length of time individual had diabetes
• Poor control of blood sugar levels over time
• High blood pressure
• High cholesterol levels
• Pregnancy in someone with diabetes
Diagnostic tests
EYE EXAM
The best way to diagnose diabetic retinopathy is with a dilated eye exam. During the exam, the physician will place drops in the eyes to make the pupils dilate (open widely) to allow a better view of the inside of the eye, especially the retina tissue.
FUNDUS PHOTOGRAPHY
The physician may take photographs of the back of the eye to facilitate detection of diabetic retinopathy and to document the retinopathy.
FLUORESCEIN ANGIOGRAPHY
To supplement the eye exam, the physician may conduct a retinal photography test called fluorescein angiography. After dilating the pupils, a dye will be injected into the patient’s arm and circulate through the eyes. The pictures are taken of the retina, allowing the physician to accurately detect blood vessels that are closed, damaged, or leaking fluid.
OPTICAL COHERENCE TOMOGRAPHY
The physician may suggest an optical coherence tomography (OCT) exam. This test provides cross-sectional images of the retina that show its thickness, helping determine whether fluid has leaked into retinal tissue.
Treatment and drugs
SURGICAL TREATMENTS
Lasers to the retina or miniscule injections of medications into the middle cavity of the eye. These procedures can be done in the office or hospital setting to prevent, treat, or reverse damage from diabetes in the retina.
The key to these treatments is the blocking by eye injections of vascular endothelial growth factor (VEGF), a chemical signal in the body that stimulates blood vessel growth. Repeated doses of anti-VEGF medications may be needed to prevent blood vessels from leaking fluid and causing damage to the eye.
PROPER EXAMINATIONS
With proper examinations, the earliest signs of diabetic retinopathy in the retina can be detected before vision loss begins. This detection is facilitated by an eye exam in which eye drops, given in the office, dilate the pupil of the eye.
Regular dilated eye exams by an ophthalmologist are important, especially for those who are at a higher risk for diabetic retinopathy or diabetes.
Prevention
CONTROL BLOOD SUGARS, BLOOD PRESSURE, AND LIPID LEVELS
Control those blood sugar levels through diet, exercise, and medications. The better control of these levels, the less likely one will develop diabetic retinopathy or have worsening of any pre-existing retinopathy.
FOLLOW YOUR EYE EXAM SCHEDULE
It is extremely important for diabetic patients to maintain the eye examination schedule put in place by the retina specialist.
Regular dilated eye exams may not prevent diabetic retinopathy, but it certainly can reduce the risk of developing more severe complications from the disease. By detecting it early, the retina specialist can begin a treatment regimen to help prevent vision loss and slow the disease’s progression.
