Can a Drug Help Prevent Diabetic Vision Loss?
The overall eye health of people with diabetes benefits from preventive drug injections directly into the eyeball, but it's too soon to tell whether such treatment will better preserve their vision long-term, new clinical trial results show.
Regular injections of aflibercept (Eylea) caused a more than threefold reduction in blood vessel leakage inside the retina, and a more than twofold reduction in abnormal blood vessel growth in the retina, researchers reported. The study was supported by the National Eye Institute, part of the U.S. National Institutes of Health, and published March 30 in JAMA Ophthalmology.
But over two years, patients given preventive injections of the drug didn't score better on vision tests than others who only received treatment once they started losing vision, the results showed.
"Based on these results, some physicians will choose to treat early because they feel that preventing the development of complications is important," said senior researcher Dr. Jennifer Sun, chief of clinical eye research and trials at Harvard Medical School's Joslin Diabetes Center in Boston. "Other physicians will feel that even though we're preventing complications, if there's no major difference in vision we might as well hold off and not expose the patient to the cost and burden and risks of treatment."
Diabetic retinopathy is the most common cause of vision loss for people with diabetes. It occurs when blood vessels swell and leak in the retina, the light-sensitive layer at the back of the eye that receives and transmits vision signals to the brain.
Drugs that inhibit the growth of blood vessels -- anti-vascular endothelial growth factor (anti-VEGF) medications -- such as Eylea are considered the "gold standard" for treating diabetic retinopathy, Sun said.
"Before these drugs were available, all we really had was laser. That was the standard of care for many years. It definitely could slow down progression of disease, but very often there was no improvement," said Dr. Richard Rosen, a retina specialist with the New York Eye and Ear Infirmary of Mount Sinai in New York City.
"These drugs have saved vision and allowed people to carry on in a more normal manner. It's really been a tremendous stride forward," said Rosen, who was not part of the study.
But it's an open question whether people with diabetes would benefit from preventive treatment with anti-VEGF drugs in the early stages of retinopathy, when changes in the eye's blood vessels are visible to doctors but haven't yet affected a person's sight.
In this study, 200 eyes with early diabetic retinopathy were assigned to receive regular injections of Eylea, while another 199 eyes were treated with a placebo. Injections were done once a month initially, but eventually went to once every four months.
If their diabetic retinopathy progressed, the people in the placebo group started receiving Eylea injections to treat their disease.
Over two years, the rate of development of proliferative diabetic retinopathy -- the late stage of the disease when new blood vessels invade the retina -- was 33% in the placebo group and 14% in the treatment group.
The rate of blood vessel leakage affecting vision was 15% in the placebo group and 4% in the Eylea group.
Loss of vision was essentially the same in both groups.
"What this study tells us is that over two years, if you don't treat immediately but do treat if complications develop, vision outcomes on average are still excellent," Sun said.
The open question is whether preventing these complications in the first place will save vision later on. Sun and her colleagues will follow patients for four years out to track their progress.
Anti-VEGF drugs like Eylea are expensive, costing between $1,000 and $2,000 per dose, and patients do face rare side effects such as infections of the eyeball, Sun said. It might not be worth the money or health risk to provide preventive treatment.
"When you're talking about a drug that's given on a very frequent basis, that adds up to a huge public health cost," Sun said.
On the other hand, doctors might be able to better preserve patients' sight if they tackle eye problems head-on.
"The idea that you can prevent progression of disease in patients is very important, and makes a lot of sense," Rosen said. "It takes many years to develop diabetic retinopathy, but there very often are things that occur for people with this disease that are unplanned and unpredicted. Anything you can do to control the progression of the disease early on makes very good sense clinically."
The U.S. National Eye Institute has more about diabetic retinopathy.
SOURCES: Jennifer Sun, MD, MPH, ophthalmologist, chief, clinical eye research and trials, Joslin Diabetes Center, Harvard Medical School, Boston; Richard Rosen, MD, retina specialist, New York Eye and Ear Infirmary of Mount Sinai, New York City; JAMA Ophthalmology, March 30, 2021