Patients Lack Awareness of How Diabetes Can Damage Vision

The rising incidence of type 2 diabetes mellitus (T2DM), especially in a region of the United States identied by the CDC as the “diabetes belt” (see FIGURE 1), has brought attention to complications that can result after years of living with the disease. Today, 9.3% of Americans have diabetes, most of them T2DM, and that share is increasing.¹ Patients who don’t follow medication, diet, and exercise regimens as well as they should can suffer a variety of ailments, including chronic kidney disease and vision loss.

John W. Kitchens, MD, an ophthalmologist and surgeon from Lexington, Kentucky, discussed how diabetes affects vision—and how it can be treated—at Patient-Centered Diabetes Care 2015.

Kitchens appeared on behalf of Regeneron, the maker of aflibercept, one of 2 FDA-approved VEGF inhibitors that have changed the way retina specialists treat conditions caused by diabetes and aging over the past decade.²

How damage occurs. When T2DM is not well controlled, Kitchens said, years of high blood sugar damages the fine blood vessels in the back of the eye, which become leaky and swell. This tends to happen in the center area of vision, causing diabetic macular edema (DME). Patients who experience this vision loss may assume it is being caused by a cataract and not take immediate action. However, if they do not act, lack of blood ow can result in retinal detachment. Kitchens said that he sees patients every day who have neve been informed of the ophthalmic effects of T2DM. “If they would have been checked, they would have been treated in a much earlier time frame,” he said, and that DME is the leading cause of vision loss in patients with diabetes.

Doctors don’t ask. How does DME progress without being caught? Primary care physicians (PCPs) are pressed for time and have much to cover when patients with diabetes come in for a visit, so unless the patient raises the issue of vision loss, Kitchens said, it doesn’t come up. Even specialists may fail to ask. Fortunately, he said, the Aordable Care Act will require PCPs to start asking questions about issues like vision loss in order to qualify for certain reimbursements.

Diagnostic test exists. Kitchens described optical coherence tomography, or OTC, which is a scan that offers a cross-sectional view of the retina. The test reveals areas of swelling below the center of vision, so it can catch developing DME even in patients who still have 20/20 vision.

“This is this patient we want to catch before it involves that center vision,” he said. And with treatment, Kitchens said, additional OTC can track improvement.

Treatment is available. Until about a decade ago, the only treatments available for ocular conditions such as DME, diabetic retinopathy, or age-related macular degeneration were laser treatments. They are still part of the arsenal in restoring vision, but today the vascular endothelial growth factor (VEGF) inhibitor is the rst-line therapy for a majority of retina specialists.² The treatment is administered by injection in the eye. As Kitchens explained, the mechanism of action is straightforward. “You take someone who has very, very high VEGF levels inside the eye in the vitreous, bind it up, and decrease the amount of VEGF that’s available to promote the swelling and promote the growth of the abnormal blood vessels in the back of the eye.” Treatment is given over a series of months, according to the protocol for the individual therapy. With VEGF inhibitor therapy, Kitchens has seen patients whose vision had deteriorated to 20/80, which bars them from driving where he lives, come back to 20/32.

Risks and side effects. Kitchens said an eye injection brings potential risks and side effects; the initial injection increases pressure, which dissipates in 3 to 5 minutes. There is a chance of retinal detachment. There can be redness initially, and there is a risk of infection (the FDA has strict requirements to prevent infection).

“Who do we want to try to intervene with?” Kitchens asked. Patients at highest risk for vision loss—and who should be targeted for screening and care—are those who have had uncontrolled diabetes for a long time but are still in their working years. These patients—aged 40 to 64 years—would be on disability if they were to go blind.

Which therapy works best? Kitchens described the results of a study by Diabetic Retinopathy Clinical Research Network, which compared aibercept and 2 competitors head-to-head in a study funded by the National Institutes of Health. Aflibercept, which is marketed as Eylea, was compared with ranibizumab, marketed as Lucentis, and its chemical “cousin,” bevacizumab, which is better known as the cancer drug Avastin. It repackaged and sold off-label for ocular treatments. The study, which was published this spring in the New England Journal of Medicine,³ found that the 3 drugs work about the same for patients who have not yet experienced severe vision loss. But for those who had more signicant vision loss at the start of treatment, aflibercept did a better job of restoring vision.

What is the cost? This can vary, Kitchens said. He has treated patients somewhat differently from the study, using a “treat and extend” procedure to keep DME from returning. Both FDA-approved VEGF inhibitors are expensive; however, it is important to note that the costs and dosing schedules are different. Aflibercept costs $1900 per injection, and its schedule calls for dosing every 4 weeks for the first 5 doses. After that, dosing is every 8 weeks.

Ranibizumab, according to Kitchens, costs $1200 to $1300 per injection, but the NEJM study said its schedule calls for dosing every 4 weeks for as long as therapy is necessary. Off-label use of bevacizumab costs $50 per injection. References

1. Statistics about diabetes. American Diabetes Association website. http://www.diabetes.org/diabetes-basics/statistics/?referrer=https://www.google.com/. Updated May 18, 2015. Accessed May 29, 2015.

2. American Society of Retina Specialists Preference and Trends (PAT) Survey 2013. http://www.asrs.org/asrs-community/pat-survey. Accessed April 23, 2015.

3. The Diabetic Retinopathy Clinical Network. Aflibercept, bevacizumab, or ranibizumab for diabetic macular edema [published online March 26, 2015]. N Engl J Med. doi:10.1056/NEJMoa1414264.