Delayed treatment safe for some people with diabetic eye disease

During the 2-year study, a research team led by Dr. Carl W. Baker, left, tested treatments on people with diabetic macular edema.Brooksie Beard

Almost 15% of people in the United States live with diabetes—a disorder in how the body uses glucose, a sugar that serves as the body’s fuel. The condition can potentially damage many parts of the body, especially if left untreated.

People with diabetes may develop a problem in their eyes called diabetic macular edema. This is a swelling or thickening of the macula, an area in the center of the retina—the part of the eye that senses light. It’s caused by damage to the small blood vessels of the retina. Diabetic macular edema is the most common cause of vision loss among people with diabetes.

If doctors detect vision loss caused by diabetic macular edema early, treatment can slow or stop it. But it hasn’t been clear if treatment should be given to people with diabetic macular edema who still have good vision.

To better understand the appropriate timing for treatment, a team led by Dr. Carl Baker from the Paducah Retinal Center in Kentucky enrolled about 700 people into a clinical trial. All participants had diabetic macular edema but still had normal or near-normal vision. The team randomly assigned participants to three groups.

One group received injections into the eye of a drug that prevents vision loss. The second group underwent a treatment called photocoagulation, which uses lasers to seal leaky blood vessels in the eye. The third group received no immediate treatment, but had their eyes checked at eight and 16 weeks after study entry, and then every 16 weeks. If vision loss began to develop in participants in this group over two years of follow-up, they immediately began drug injections.

The study was funded by NIH’s National Eye Institute (NEI) and National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Results were published on April 29, 2019, in JAMA.

Due to progressive vision loss, 25% of people in the photocoagulation group and 34% of people in the observation group started drug injections. At the end of the study, rates of vision loss were about the same between the three groups, regardless of what treatment they started with. After two years, the average vision was 20/20 in all groups—the same as at the start of the study.

Increases in pressure within the eye were more common in the drug injection group than in the observation group. Other side effects did not differ between the groups.

“We now know that in patients with good vision and diabetic macular edema, similar to those enrolled in this trial, it’s an acceptable strategy to closely monitor patients, and initiate treatment only if their vision starts to show signs of decline,” Baker says.

Participants in the trial had good control of their blood sugar, which helps prevent diabetic eye disease, and came in for regular checkups. The researchers caution that delaying treatment may not be as safe for people who have trouble managing their blood sugar or coming in for regular eye exams.