By David H. Perlmutter, MD
Diabetes is an epidemic in the United States with tremendous public health implications. The Centers for Disease Control (CDC) estimated that in 2015 around 30 million people in the Unites States had diabetes, approximately 9.4% of the entire population. Over 7 million people in the United States who have diabetes have not yet been diagnosed. Therefore, they do not even know that they have the condition. Another 84 million adults in the United States have pre-diabetes, a condition that often leads to diabetes, and the numbers continue to rise. You are at a higher risk for developing diabetes if you have an immediate family member with diabetes.
What is diabetes?
Diabetes occurs when there is elevated sugar in the blood stream of the body. Under normal conditions, the human body does an excellent job of maintaining sugar levels in the blood stream within a healthy range. Sugar is necessary for all organs to function, and insufficient levels are dangerous. On the other hand, elevated blood sugar levels damage blood vessels throughout the body. Blood vessels are like pipes that carry vital nutrients to organs throughout the body in order to keep those organs functioning, and damage to them over time leads to heart attacks, strokes, kidney disease, neuropathy, and blindness. Controlling the blood sugar with a combination of diet, exercise, oral medications, and insulin can slow the blood vessel damage and decrease the risk of major complications.
How can diabetes affect my eyes?
Diabetes can cause a range of damage to the eyes, from mild visual loss to complete blindness, and it is a leading cause of new cases of legal-blindness in working-age adults in the United States. Sadly, many cases of blindness and vision damage could have been prevented with currently available examination, diagnostic, and treatment technologies.
Vision loss from diabetes usually occurs due to diabetic retinopathy, a generic name for damage to a structure inside the eye called the retina. The retina is a thin layer of tissue lining most of the back wall of the eye, and its healthy function is vital to maintaining good vision. Diabetic retinopathy occurs when elevated sugar in the blood causes damage to blood vessels in the retina over time. With progressive damage, the shape of the blood vessel and the integrity of its wall deteriorate. The blood vessels can then become leaky or completely shut down.
When the blood vessels become leaky, water, protein, and blood from inside the blood vessels pass through the damaged blood vessel walls into the surrounding retinal tissue, causing it to swell. The swelling decreases the vision and over time leads to permanent irreversible damage to the retina and to the vision. This swelling, called macular edema, is the most common cause of vision loss in diabetes.
When the blood vessels become closed down, areas of the eye supplied by these non-functioning blood vessels become ischemic. Areas of the eye become starved for nutrients and oxygen. This is similar to what happens in the heart with a heart attack or the brain with a stroke. To compensate for the loss of blood flow, the eye stimulates the production of new blood vessels. The new blood vessels can bleed easily or grow over vital structures. This is known medically as proliferative diabetic retinopathy, and can lead to detachment of the retina or large amounts of bleeding into the eye.
How can I protect my eyes from diabetes?
The number one modifiable risk factor for developing diabetic damage to the eyes is controlling the blood sugar. There is a tremendous amount of data showing that the better the blood sugar is controlled, the less likely that a person will lose vision from diabetes. Some additional steps that may help limit the development of diabetic damage to the eyes include controlling blood pressure and cholesterol, but these are not as well supported.
Even with reasonable blood sugar control, the majority of people with diabetes will develop retinopathy. The longer that a person has diabetes, the more likely that diabetic retinopathy will develop, and in people with diabetes for over 15 years, around 60-80% will have some form of diabetic retinopathy. The single most important method to identify, treat, and protect the vision from diabetic damage is a yearly dilated eye exam. Unfortunately, it is estimated that up to 65 percent of people with diabetes do not receive a yearly dilated eye exam. Protecting the eyes from diabetic retinopathy, therefore, requires a team approach among patients, primary care physicians, and ophthalmologists. Years of diligent monitoring are necessary for early detection and treatment.
When diabetic retinopathy is identified on a dilated examination, it may require more frequent follow up or additional technology to evaluate the effect on the vision. High definition imaging of the retina with optical coherence tomography (OCT) can illustrate areas of swelling in the retina as small as thousands of a millimeter. Additionally, areas of blood flow, leaking blood vessels, and new blood vessel growth can be visualized with specialized angiography imaging.
What treatments are available for diabetic retinopathy?
As technology has improved to detect early diabetic retinopathy, the development of targeted drug therapies has provided new opportunities to effectively treat the disease and prevent vision loss. It is estimated that current treatment strategies are over 90% effective at preventing severe vision loss from diabetic retinopathy.
Traditional treatments involve the use of laser to decrease areas of swelling in the retina. Additionally, laser can be used to inhibit the growth of dangerous new blood vessels. Laser treatments work by causing direct damage to retinal tissue, and they therefore have potential side effects of decreased peripheral vision or decreased night vision. Lasers cannot be used in the center areas of the vision, which are the most vital, as this would cause permanent blind spots in the central vision.
Newer medications that slow the leakage from damaged blood vessels and shrink down new blood vessels are now available. These medications are powerful and effective. They are given as a direct injection into the eye, and they work throughout the entire eye and the entire retina. However, they only last inside the eye for weeks to months, and they need to be administered frequently. Some eyes can require monthly injections for years. Thankfully, there are current clinical trials for longer-acting medication, as well as delivery devices to decrease the need for frequent injections of medication into the eye.
If you or your family member has diabetes, schedule your yearly eye exam with an ophthalmologist
Diabetes is rising in our country and is very dangerous for vision. Vision loss from diabetic retinopathy is the top cause of legal blindness in working-age adults in the United States. If you or a family member has diabetes, please schedule your dilated eye exam today with a qualified ophthalmologist.
Dr. David H. Perlmutter, MD, is a board-certified ophthalmologist and partner at Perlmutter Eye Center in Albany NY. He specializes in customized cataract surgery and retinal diseases. perleyecenter.com; 518.472.9111.