Editor’s Note: This article was written by the Joslin Diabetes Center, which is the world’s largest diabetes research center, diabetes clinic, and provider of diabetes education. It was founded in 1952 and is located in Boston, Massachusetts, USA.
In 1921, the introduction of insulin revolutionized the treatment of diabetes. Yet, as Eliot P. Joslin himself noticed, as patients lived longer, they developed unexpected complications. One of the most severe complications was diabetic eye disease.
Diabetic retinopathy is the most common vascular complication of diabetes, and the leading cause of vision loss among working age Americans. Experts estimate a half a billion eyes will be affected by diabetic retinopathy worldwide by the year 2030. Left untreated, it leads to blindness after 20 to 30 years with diabetes.
Reasons for vision loss:
- Macular edema – when blood vessels leak
- proliferative diabetic retinopathy – when blood vessels grow haphazardly on the retina.
Both can block the vision centers within the eye, resulting in reduced ability to see clearly and potentially eventually leading to complete blindness. Most strikingly, the disease can be rapidly destroying the eye’s blood vessels without any noticeable symptoms. This is why doctors stress the importance of regular in depth eye exams — the best way to catch the disease before it does irreparable harm.
Eyes are sensitive organs, made up of a network of blood vessels and sensors that translate the light pouring in every second into comprehensible objects. “Images come in through the pupil, which is just an opening in the iris,” explains Phillip Silver, O.D., Optometrist in the Beetham Eye Institute, “Those images eventually hit the inner wall of the eyeball which is the retina.”
The retina helps us process what we see. “The retina is the thin film or membrane that lines the back of the eye,” says Jennifer Sun, M.D., MPH, an Investigator in the Section on Vascular Biology, an ophthalmologist in Beetham Eye Institute at Joslin and Associate Professor at Harvard Medical School. “Light that comes into the eye actually gets sensed by the cells in the retina and these cells then transmit the light and information through the optic nerve into the brain so it gets processed.” If any one part of this network is misshapen or out of balance, a patient’s vision becomes distorted.
Macular edema can arise on its own or when the eye tries to make new blood vessels. Making new blood vessels means breaking the old ones apart, causing them to leak which may block the central vision cells in the retina.
Diabetic retinopathy causes changes in the blood vessels of the retina. The complications start when high blood sugar causes loss of capillaries and thus reduced oxygen, triggering a repair response that stimulates new blood vessel growth in an attempt to bring more oxygen to the choking retina. Proliferative diabetic retinopathy arises from the lack of oxygen, when new retinal blood vessels form in a disorganized way, frantically trying to make up for the lost oxygen. This chaotic proliferation could eventually pull the retina off of the back of the eye, causing complete blindness.
The risk of this scary disease happening to you can be reduced by getting regular retinal exams from an expert in diabetic eye care. These exams traditionally come in the form of a dilated eye exam. Newer technology, however, has allowed some eye doctors to take a picture of a non-dilated pupil and see more of the retina than ever before, including the parts around the edges, called the periphery. “The importance of the retinal periphery has been recognized for a long time, but we didn’t have the technology to image it until recently,” says Paolo Silva, M.D., Staff Ophthalmologist and Assistant Chief of Telemedicine in the Beetham Eye Institute at Joslin Diabetes Center. “With [this new imaging], we’re able to see 82 percent of the retina in a single 200⁰ retinal image, with high resolution.”
You can work towards keeping your eyes healthy between eye doctor visits by tightly controlling blood sugars. It’s important to remember, though, that many people with diabetic retinopathy experience no symptoms, but they should still be screened yearly for progressing disease.
The good news is that there are treatments for diabetic retinopathy, particularly if it’s discovered in an early stage. One treatment involves a laser beam closing the leaky blood vessels. This is effective in preventing progression of the disease in many patients, but it doesn’t improve vision. But a course of treatment known as anti-VEGF injections developed at Joslin Diabetes Center in the past decade have shown to not only halt the disease progress but improve vision in many patients.
“Laser still has a role in treatment…for some patients,” says Dr. Sun. “But anti-VEGF therapy gives us another tool in our search for better vision outcomes in our patients with diabetes.”
Read Samantha Willner’s account of nearly going blind in Seeing Clearly.