People taking Ozempic and Wegovy may be at increased risk of developing a debilitating eye condition that can cause irreversible vision loss, a study published Wednesday in JAMA Ophthalmology finds. The authors stressed, however, that more studies are needed to confirm a link between the blockbuster drugs and vision problems.

Non-arteritic anterior ischemic optic neuropathy, or NAION, is a condition that affects the optic nerve, a bundle of fibers that connects to the back of the eye and carries signals to the brain so a person can see. In people with NAION, blood flow to the optic nerve gets reduced or blocked, leading to sudden vision loss.

“It is, in effect, a stroke of the optic nerve,” said senior study author Dr. Joseph Rizzo, the director of neuro-ophthalmology at Mass Eye and Ear in Boston.

NAION is the second most common optic nerve disease in the U.S., occurring in up to 10 out of 100,000 people, according to the American Academy of Ophthalmology, and it’s one of the most common causes of sudden blindness. The condition is permanent with no known treatment. 

The new study was based on an analysis of medical records spanning six years from more than 16,800 patients in the Boston area, none of whom were initially diagnosed with NAION. 

The researchers focused on a subset of those patients — about 1,700 — who either had diabetes, were overweight or had obesity, and compared outcomes after 36 months in those who were prescribed semaglutide to those who weren’t. Semaglutide is the ingredient in Ozempic and Wegovy

Almost 200 of the diabetes patients were prescribed semaglutide and 17 went on to develop NAION, a rate more than four times higher than those not prescribed the drug. For the obesity group, 361 people were prescribed semaglutide and 20 people developed the condition, a seven times higher rate. 

Rizzo said that because the findings were based on a review of existing data, researchers can’t say for sure whether semaglutide causes the eye condition. He said a large, randomized controlled clinical trial is still needed to confirm a link. 

“What it does show is an association between taking semaglutide and developing this condition where you lose vision,” he said. 

Dr. Andrew Lee, clinical spokesperson for the American Academy of Ophthalmology and a neuro-ophthalmologist at Houston Methodist Hospital, said he’s had some patients who developed NAION who were taking semaglutide, but the question was always whether “this is a causal association or merely an association alone.” 

People with Type 2 diabetes are already at an increased risk for vision problems, including NAION. Another vision problem, diabetic retinopathy, is the leading cause of blindness in adults and is caused by damage to the retina from high blood sugar levels.

What’s more, risk factors for NAION include sleep apnea and hypertension, which are diseases that are more likely to occur in people with obesity. 

Lee said that it’s plausible that weight loss medications could cause the condition, however, it is “premature to conclude” a link based on the single study. “The ​​study can only generate the hypothesis” of a possible link, he said. 

There have been some anecdotal reports suggesting that weight loss drugs may be linked to vision problems, including blurred or warped vision. 

Rizzo said it’s unclear how the weight loss drugs could cause the condition. It could be due to some mechanism with the class of drugs, called GLP-1s, broadly, he said, or something specific to the way semaglutide works. (The study only looked at semaglutide and not other popular weight loss medications such as tirzepatide, the active ingredient in Eli Lilly’s Mounjaro and Zepbound.)

Dr. Susan Mollan, a consultant neuro-ophthalmologist at the University Hospitals Birmingham in the United Kingdom, wrote in an email that past trials in people with diabetes have shown that when a patient’s blood sugar control is tightened, “they may have a paradoxical worsening of their diabetic retinopathy (temporarily),” so it’s plausible that the GLP-1 drugs, which also help control blood sugar, could “have a paradoxical biological effect.” Mollan wrote an editorial that was published alongside the new study.

Rizzo said patients should speak with their doctor if they are concerned about developing the potential health condition.

“As someone who sees patients who have diseases like this, if someone already has visual loss for whatever reason, and they were wondering whether they would go on semaglutide, I would just have added caution,” Rizzo said.

Dr. Shauna Levy, a specialist in obesity medicine and the medical director of the Tulane Bariatric Center in New Orleans, said the findings won’t change how she prescribes the drugs.

“As for now, the risk still seems low,” she said. 

In a statement, a spokesperson for Novo Nordisk said the study is not sufficient to establish a link between semaglutide and the condition.

“Patient safety is a top priority for Novo Nordisk, and we take all reports about adverse events from the use of our medicines very seriously,” the spokesperson said.


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