Diabetic eye disease is a group of eye problems that people with diabetes may face as a complication of diabetes. Karen Gehrs, MD, ophthalmologist at University of Iowa Hospitals and Clinics, talks about diabetic eye disease:
What causes diabetic retinopathy or eye disease in a person with diabetes?
Diabetic retinopathy means there is damage to the retina of the eye, which is like the film in the camera, if you think of your eye like a camera. The reason it becomes damaged is that diabetes damages circulation all over the body. When it damages circulation in the retina, not getting enough blood supply or oxygen, that causes damage to the retina tissue and the tissue may swell or it may bleed. It’s the circulation damage caused by diabetes that causes the diabetic retinopathy.
Are there signs or symptoms a diabetic might experience if they were developing an eye disease?
Early in the course of diabetic retinopathy, there are usually no symptoms. In fact, for the first five to 10 years, a patient may have slowly developing diabetic retinopathy. Until they develop swelling or bleeding, they may still have normal vision, even though things are happening that are threatening their vision. Once swelling occurs—if it’s near the center of vision—things may be blurry or look a little wavy to the involved eye. If someone develops hemorrhaging, they usually notice things like strings or blobs or sometimes a sensation that pepper’s been sprinkled, or they may just see a floater go by. So any of these symptoms: blurry vision, floaters, or strings or webs or blobs in the eye could be symptoms of the complications of diabetic retinopathy.
How is diabetic eye disease detected?
The gold standard is a dilated eye exam once a year. There are some camera systems now that are pretty good at detecting retinopathy in the area of the retina that’s most likely to be affected, and they’re used as a screening tool. People who know they’ve had a dilated eye exam and have had no retinopathy can, in certain situations, can have taken photos once a year. But the gold standard is still a dilated eye exam once a year.
Are diabetics also at higher risk to develop glaucoma or cataracts in their eyes?
They are at a higher risk to develop cataracts. Glaucoma—not so much so, unless there is a special type of glaucoma called neovascular glaucoma that can occur when the eye is severely starved for oxygen, but that usually is in the very late stages of diabetic retinopathy. But in general, routine, open-angle glaucoma is no more common in people with diabetes than people without; but cataracts are more common.
Do people who maintain their diabetes well also reduce their chances of developing diabetic eye disease?
Yes, and that’s a very important point. Many studies have been done show that good diabetes control lowers the risk of developing retinopathy and lowers the risk of worsening retinopathy in people who already have it, for both type 1 and type 2 diabetes.
Ideally, we recommend that patients work with their primary care physician or diabetes specialist to try to achieve a hemoglobin A1C of 7.0 or less. There are a number of studies that show that when it’s less than that, the risk of getting worse is extremely low. Once you get above hemoglobin of A1C of 8.0, the risk goes up pretty fast.
We realize that that isn’t practical for some people and for some people it’s actually too risky to try to shoot for too low of a hemoglobin A1C, because they can run the risk of running too many low blood sugars. So that’s why the hemoglobin A1C of 7.0 or less is a target, but it does have to be individualized, and that’s why it’s so important that patients communicate with their eye doctor, the doctor managing their diabetes, and make sure that those two doctors are communicating with each other.
How are diabetic retinopathy and eye disease treated?
The gold standard for treating diabetic retinopathy, once it reaches the treatment stage—not all retinopathy has to be treated, so if it’s before the laser treatment stage—the treatment is treat your diabetes and try to keep it from progressing.
Once it gets to the stage we call clinically significant edema—swelling that’s threatening the center vision—or high risk proliferative disease—growth of new blood vessels that have achieved a certain stage—then laser treatment is the gold standard therapy. This has been proven in many studies done since about 1979, when the first study was published, and there have been numerous studies since.
In recent years, there has been the addition of medications we inject in the eye—steroid medications and other medications that are sometimes used to treat another disease (macular degeneration)—to help slow the growth of blood vessels or make swelling improve. It’s important to remember that those injections are what are called off-label therapy, they are not FDA-approved. There are studies investigating them, but they are not as big as the laser studies. So they’re an exciting addition to laser, but laser’s still the gold standard for both diabetic macular edema and proliferative retinopathy.
If left untreated, can diabetic eye disease cause blindness?
Yes it can. Once a patient reaches the threshold for laser, there are several studies—one was called the Diabetic Retinopathy Study that was done in the late 70s/early 80s and another one was called the Early Treatment Diabetic Retinopathy Study done in the 80s—and both of them clearly demonstrated that when they compared patients who had laser to similar patients who didn’t, the patients who didn’t have laser were much more likely to lose vision and even become blind, than the patients who had laser. |
