November is both American Diabetes Month and Diabetic Eye Disease Month. More Americans than ever have diabetes. In fact, 8 percent of the population has diabetes - 23.6 million children and adults. Of those individuals, only about 18 million have been diagnosed. Additionally, some 57 million Americans are pre-diabetic.
Many Americans do not know that untreated diabetes can lead to complete vision loss. Emory Eye Center ophthalmologists routinely treat patients who have the particular complications of diabetes that affect their vision.
All people with diabetes, both type 1 and type 2, are at risk. Those who have had diabetes for 15 years or more are at strong risk of developing this sight-stealing disease called diabetic retinopathy. It affects between 12,000 and 24,000 people with diabetes each year in this country, and is the leading cause of blindness in people ages 20 to 74, according to the American Academy of Ophthalmology.
The longer someone has diabetes, the more likely he or she will get diabetic retinopathy. Between 40 percent to 45 percent of Americans diagnosed with diabetes have some stage of diabetic retinopathy.
"At Emory, we treat a significant number of patients who have diabetic eye disease, says Baker Hubbard, MD, director of Emory Eye Center's Retina service and associate professor of ophthalmology, Emory University School of Medicine. "It is important for diabetics to be diagnosed early, and to begin treatment early to avoid vision loss. Past studies have shown that intensive therapy at diagnosis reduces the risk for developing retinopathy by 76 percent. It is much easier to prevent vision loss with intensive control of blood sugar than it is to restore vision after it has already been lost."
Diabetic retinopathy is a complication of diabetes, which can weaken the retina and block, distort or blur vision. Diabetes sometimes causes abnormal blood vessels to form in the back of the eye. With diabetic retinopathy these new vessels can leak fluid into the retina or vitreous humor (the jelly that fills the eye) and contract, distort or detach the retina.
The early stage of diabetic retinopathy is nonproliferative diabetic retinopathy (NPDR), which occurs when tiny blood vessels within the retina leak blood or fluid. The leaking fluid causes the retina to swell or to form deposits called exudates. Many with diabetes have mild NPDR, which does not typically affect their vision. When vision is affected, it is the result of macular edema (swelling of the macula) and/or macular ischemia (when small blood vessels close).
Proliferative diabetic retinopathy (PDR) is present when abnormal, new vessels (neovascularization) begin growing on the surface of the retina or optic nerve. Adequate blood supply is prevented, causing the retina to respond by growing these new vessels. Unfortunately, the new vessels do not resupply the retina with normal blood flow, and these new vessels are often accompanied by scar tissue that may cause wrinkling or detachment of the retina.
PDR causes more severe vision loss when the new vessels bleed into the vitreous, the clear, jelly-like substance that fills the eye. A very large hemorrhage might block all vision. Smaller ones cause dark floaters in one's vision. With time, this new blood in the vitreous may clear or it may be necessary to perform a surgery to do so.
"A dilated eye exam is the only way to find these changes inside one's eye," says Hubbard. "We can often diagnose and treat a patient's retinopathy before that patient is aware of any problems."
During the early stages of diabetic retinopathy, no treatment is needed, unless the patient has macular edema. Proliferative retinopathy has been treated with laser surgery for the past few years. On occasion, more than one laser treatment is required.
Today, physicians have also added anti-VEGF injections, similar to those used for age-related macular degeneration (AMD), to their arsenal of treatment options. These compounds inhibit the formation and leakage of new blood vessels, just as they do in the treatment of AMD.
If the bleeding is severe, a surgical procedure called a vitrectomy is used. During a vitrectomy, blood is removed from the center of the eye.
During Diabetic Eye Disease Month, eye MDs at Emory Eye Center urge all those at risk for or who already have diabetes to have an annual eye exam. Prevention is key in order to save sight that might be lost due to late diagnosis.