|Diabetic retinopathy damages the blood vessels that nourish the retina.
Diabetic retinopathy (dye-uh-BET-ick ret-in-AHP-uh-thee) is a condition in which high levels of blood glucose (sugar) caused by diabetes damage blood vessels in the
retina. When damaged, these vessels become clogged or leak and are unable to deliver an adequate supply of nutrients to light-sensitive cells in the retina.
Like other types of retinopathy – a broad term that refers to diseases affecting the retina, usually because of abnormalities in these retinal blood vessels – diabetic retinopathy can cause partial or complete vision loss. It affects about half of the 14 million Americans with diabetes, and the primary reason why diabetics are four times more likely than the general population to suffer vision loss. Other forms of retinopathy, which occur less frequently, are caused by uncontrolled high blood pressure, premature birth or low birth-weight (and subsequent oxygen therapy) long-term intravenous drug abuse and other factors.
Anyone with Type 1 or Type 2 diabetes is at risk for diabetic retinopathy, the most common cause of vision loss in adults between ages 20 and 74. But the longer you have diabetes, the greater your risk. About one in five newly diagnosed Type 2 diabetics show signs of diabetic retinopathy; after 15 years with diabetes, that jumps to nearly 80 percent of Type 2 (and nearly all of those with Type 1).
Besides duration, certain groups of diabetics seem to be at greater risk of developing diabetic retinopathy:
- Pregnant women
- Those of African, Mexican and Native American descent
- Those who developed the diabetes early in life, or have high blood pressure and/or kidney damage.
In the early stages of diabetic retinopathy, tiny blood vessels in the retina become blocked or damaged, cutting off the food supply to small patches of light-sensing cells. Blood leaks into retinal tissue, causing swelling. At first, sight is rarely affected. This stage is called "background retinopathy." Unless complications develop, treatment is rarely necessary for the disease in the early stage.
As the disease progresses, it enters an advanced or "proliferative stage" in which new, fragile blood vessels grow along the retina and in the clear, gel-like
vitreous humor that fills the inside of the eye. Without timely treatment, these new blood vessels can bleed, cloud vision, and destroy the retina.
There are several complications that can occur in this proliferative stage:
- Macular edema occurs when the damaged blood vessels leak fluid and lipids onto the macula, the part of the retina that lets us see detail. The fluid makes the macula swell, blurring vision and making it hard to do tasks such as reading, watching television and driving. If not treated promptly, macular edema may cause permanent vision loss.
- Scar formation occurs as the body works to repair damage to the retina. Eventually, scar tissue can detach the retina from the back of the eye, causing permanent vision loss. If caught early, vision loss can be prevented or limited.
- Vitreous hemorrhage occurs when abnormal vessels bleed into the vitreous humor, blurring vision. Specks of blood may float through the field of vision. Large leaks, which often occur during sleep, can obscure sight, making it difficult to tell light from dark. The blood may clear on its own in a few days, but it may take months or even years. Type 1 diabetics are more likely to suffer total vision loss from large blood vessel hemorrhages.
Diabetic retinopathy often has no early warning signs. Once it advances, you may notice viusual changes such as:
- Blurred vision
- Sudden loss in vision in one or both eyes
- Changes in vision throughout the day
- Black spots
- Flashing lights
- Difficulty reading or seeing detailed work
Better control of blood sugar levels can prevent or delay the complications of diabetic retinopathy. Research shows that people with insulin-dependent (Type 1) diabetes who tightly control their blood sugar levels have 76 percent less eye damage than those who don't.
Some eyecare providers also advise the use of prescription supplements rich in specific vitamins and minerals to nourish the compromised retinal tissue and help prevent the onset or progression of diabetic retinopathy.
To decrease the risk and progression of diabetic retinopathy, blood sugar and blood pressure must be tightly controlled in all diabetic patients. Two surgical treatments are effective in reducing vision loss -- even people with advanced retinopathy have a 90 percent chance of keeping their vision when they undergo treatment before the retina is severely damaged. However, neither treatment is a cure.
- Laser surgery is done to seal leaky blood vessels, control swelling under the macula and inhibit the growth of new blood vessels. This procedure is performed in a doctor's office or eye clinic and only takes a few minutes. After your pupils are dilated and drops are applied to numb the eye, you face the laser machine, and your doctor will hold a special lens to your eye. You may see green or red flashes of light, which may create a stinging sensation. For a day or two, you may experience blurry vision and eye soreness, which is controlled with medication.
To control swelling under the retina’s central spot or macula, short bursts of laser are aimed directly at leaky blood vessels to vaporize or seal them – a procedure known as "focal laser therapy." When the likelihood of blindness is high, "scatter laser therapy" is used to control the widespread growth of abnormal blood vessels; rather than hitting just one spot, the laser beam makes hundreds of tiny burns over the retina’s surface. Some peripheral or side vision is sacrificed to save the remaining vision.
Laser surgery can also seal the retina to the back of the eye, preventing permanent vision loss from retinal detachment. Timely laser surgery can stabilize vision, but it cannot restore lost sight or repair a damaged retina. Laser surgery, however, can affect night vision and your ability to distinguish colors.
- Vitrectomy is a procedure in which the surgeon removes bloody vitreous from the eye and replaces it with a clear solution. Light can pass through this clear fluid, restoring normal sight. Since normal vitreous is mostly water, you won’t notice any difference between it and the clear fluid. Early vitrectomy is especially important for people with Type 1 diabetes, who are more likely to go blind as a result of large leaks (hemorrhaging).
Depending on your health and eye structure, this procedure may be done in hospital under general anesthesia or in a doctor's office under local anesthesia. The surgeon makes a small cut in the white of the eye. A special instrument sucks out the vitreous, then floods the eye with clear fluid. Afterward, an eye patch is worn for a few days or weeks. The eye will be red and feel sensitive, and eye drops are used to ward off infection.