People prescribed the drug semaglutide, known commercially as Ozempic and Wegovy, have a higher risk of developing a type of blindness caused by a disease of the optic nerve called non-arteritic anterior ischemic optic neuropathy, a new study led by researchers at Mass Eye and Ear Hospital has found.
The results of the study, published July 3 in JAMA Ophthalmologica, significantly indicated that people with diabetes who were prescribed semaglutide by their doctor and filled the prescription were more than four times more likely to be diagnosed with non-arteritic anterior ischemic optic neuropathy, while people who were overweight or obese and were prescribed the drug were more than seven times more likely to be diagnosed with the condition.
Non-arteritic anterior ischemic optic neuropathy
Non-arteritic anterior optic neuropathy is relatively rare, occurring in about 10 in 100,000 people. It is the second leading cause of optic nerve blindness (the first is glaucoma), and the most common cause of sudden optic nerve blindness. Non-arteritic anterior optic neuropathy is thought to be caused by decreased blood flow to the optic nerve head, leading to permanent vision loss in one eye.
How did the story begin?
The impetus for the study began in late summer 2023, according to EurekAlert, when Dr. Joseph Rizzo, director of the Neuro-Optical Medicine Service at Mass Eye and Ear and professor of ophthalmology at Harvard Medical School in the United States, and other neuro-optometrists at Mass Eye and Ear noticed something disturbing: Three patients had been diagnosed with vision loss from this relatively rare disease in just one week. All three patients were taking the drug semaglutide.
According to Rizzo, the visual loss from NAIOP is painless, may progress over several days before settling, and there is little chance of improvement. But there are currently no effective treatments for NAIOP.
This incidental discovery led the research team at Mass Eye and Ear Hospital to conduct a retrospective analysis of a group of patients to see if they could identify a link between this disease and these increasingly popular medications.
The researchers analyzed the records of more than 17,000 patients from Mass Eye and Ear Hospital who had been treated over the six years since Ozempic was launched, and classified the patients according to whether they were diagnosed with diabetes or overweight/obesity. The researchers compared patients who received prescriptions for semaglutide with those who took other diabetes or weight-loss medications. They then analyzed the rates of diagnoses of non-arteritic anterior ischemic optic neuropathy in the groups.
Ozempic and Wegovy
Semaglutide was developed to treat type 2 diabetes. The drug promotes weight loss and has been widely used since its launch under the brand name Ozempic for diabetes in 2017. The drug was also approved for weight loss, under the name Wegovy, and was released in 2021.
“These drugs have become widely used in industrialized countries and have provided significant benefits in many respects, but future discussions between patients and their physicians should include non-arteritic anterior ischemic optic neuropathy as a potential risk,” Rizzo said. “It is important to appreciate that the increased risk is for a relatively rare disorder.”
Important but not conclusive results
There are several limitations that prevent the study results from being generalizable. MAS Eye and Ear Hospital sees an unusual number of people with rare eye diseases, and the number of cases of non-arteritic anterior ischemic optic neuropathy seen over the six-year study period was relatively small. The researchers were unable to determine whether the patients were actually taking their medications.
Importantly, the study does not prove causality for blindness (that is, the study cannot prove that the drug caused the condition), and the researchers do not know why or how this association came about, or why there was a difference between the diabetic and overweight groups.
“Our results should be viewed as important but tentative,” says Rizzo. “Future studies are needed to examine these questions in a larger, more diverse group of patients.”
“This is information we didn’t have before and should be included in discussions between patients and their doctors, especially if patients have known optic nerve problems such as glaucoma or if there has been significant prior vision loss from other causes,” he adds.