Ozempic, Wegovy linked to unusual blinding eye condition: study

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Users of Ozempic and related trendy weight-loss drugs may be more likely to develop a rare form of blindness, researchers are reporting.

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The study found that a prescription for Ozempic and other drugs containing the active compound, semaglutide, was associated with an increased risk of NAION, or nonarteritic anterior ischemic optic neuropathy.

It’s a mouthful, but relatively rare, affecting two to 10 in every 100,000 people per year. The blinding eye condition causes sudden and painless but permanent loss of vision in one eye due to insufficient blood flow and oxygen to the optic nerve. It’s sometimes referred to as an “eye stroke” and is a significant cause of blindness among adults.

Researchers at Mass Eye and Ear in Boston, Massachusetts, a Harvard Medical School teaching hospital, became motivated late last summer to look at whether today’s highly sought-after weight-loss drugs might be associated with an increased risk of NAION, after three patients, all taking semaglutide, were diagnosed with the condition within the same week.

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Their study, published today in JAMA Opthalmology, found people prescribed semagultide for obesity were seven times more likely to get a diagnosis of NAION than people prescribed different drugs for being overweight. People prescribed semaglutide for type 2 diabetes were four times more likely to get the rare eye diagnosis.

“Our main finding is that prescribed semaglutide is associated with an increased risk of NAION,” the researchers wrote.

The study wasn’t designed to answer whether there is a casual relationship between the two. Given the millions of people taking the drugs globally, “we should be confident that if corroborated, the absolute risk of developing NAION in direct relation to taking semaglutide must indeed be rare,” Dr. Susan Mollan, a University of Birmingham professor who investigates rare diseases of the eye and brain, wrote in an accompanying commentary. She also added that the potential risk shouldn’t dissuade people from using GLP-1 drugs for diabetes or obesity “at this time.”

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The findings  “should be viewed as being significant but tentative,” Dr. Joseph Rizzo, director of the neuro-ophthalmology service at Mass Eye and Ear said in a statement. While NAION is relatively uncommon, people should discuss the potential risk with their doctors, he said.

In a statement to the National Post, Novo Nordisk, makers of Ozempic and Wegovy, said the data from the single-centre study are not sufficient to establish a cause-and-effect association between semaglutide and NAION, and that “key methodological limitations of the study” need to be considered when interpreting the findings.

“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 company said.

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“Semaglutide has been studied in large real world evidence studies and robust clinical development programs with a cumulative exposure including from post-marketing use of over 22 million patient years. The totality of data provides reassurance of the safety profile of semaglutide.”

Both Ozempic and Wegovy belong to a class of drugs called GLP-1 agonists that spur the release of insulin, lowering blood sugar, but that also act on the brain to curb appetite. Typically given via a once-weekly injection with a pre-filled pen, a survey released in March by Dalhousie University’s Agri-Food Analytics lab, in partnership with market research firm Caddle, found about 10 per cent of the adult population in Canada uses a GLP-1 type drug for diabetes, weight loss or both.

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But as their popularity grows, so are reports of potential unforeseen side effects, including gastrointestinal problems and unplanned pregnancies.

For the study, Rizzo and his team did a retrospective study, meaning they looked back at the records of patients referred to their clinic from December 2017 — when Ozempic was approved in the U.S. to treat diabetes — through Nov. 30, 2023, checking for diagnoses of NAOIN. (Wegovy, a higher-dose version of the drug, was approved in the U.S. in December 2022 to treat obesity.) In all, the records of nearly 17,000 patients treated over the six years were analyzed.

There were 629 NAION cases over six years.

Researchers divided people into two groups: those diagnosed with type 2 diabetes and people living with obesity. Next, they compared people who had received prescriptions for semaglutide to those taking other diabetes or weight-loss drugs.

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Among people with diabetes, 8.9 per cent of the semaglutide-treated group developed NAION over about three years of follow up, compared to 1.8 per cent for the non-semaglutide group.

For overweight or obese people, 6.7 per cent in the semaglutide group were diagnosed with NAION, versus 0.8 per cent of those prescribed other weight-loss drugs.

The researchers couldn’t determine if people actually took the drugs as prescribed, which could have led to an inaccurate estimation of the risk. “We did, however, confirm that prescribed doses of semaglutide were dispensed for all patients with NAION,” they reported.

The total number of NAION cases in those prescribed semaglutide (17 in the diabetes group, and 20 in the overweight/obese group) was also relatively small. The researchers controlled for factors that might contribute to the risk of NAION, like age, high blood pressure, obesity, diabetes, coronary artery disease and high cholesterol, but semaglutide appeared primarily associated with the heightened risk, they said.

Novo Nordisk said other important “confounders,” like smoking and “optic disc morphology” weren’t considered in the analysis.

National Post

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