Study finds link between Ozempic and increased risk of vision loss

Researchers analysed medical records of 16,800 patients in Boston over six years for the new study

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People taking Ozempic and Wegovy, which contain the drug semaglutide, may be at an increased risk of developing a debilitating eye condition that can cause irreversible vision loss, according to a study published in JAMA Ophthalmology on Wednesday.

The study highlighted a possible link between semaglutide and non-arteritic anterior ischemic optic neuropathy (NAION), a condition that can lead to sudden blindness. However, the authors stressed that further research is needed to confirm any direct connection between the drug and vision issues.

NAION occurs when blood flow to the optic nerve, which transmits visual signals from the eye to the brain, is reduced or blocked. This results in sudden, often permanent, vision loss. Describing the condition, Dr. Joseph Rizzo, the director of neuro-ophthalmology at Mass Eye and Ear in Boston, explained: “It is, in effect, a stroke of the optic nerve.”

The condition is the second most common optic nerve disease in the United States, affecting up to 10 in every 100,000 people. It is also one of the leading causes of sudden blindness, with no known treatment available.

For this new study, researchers analysed the medical records of over 16,800 patients in the Boston area over a six-year period. The focus was on a subset of around 1,700 individuals who had either diabetes or obesity, conditions that are already linked to higher risks of NAION. They compared the outcomes of those who were prescribed semaglutide, the active ingredient in Ozempic and Wegovy, with those who were not.

Among the diabetes patients, almost 200 were prescribed semaglutide, and 17 developed NAION—a rate more than four times higher than those who didn’t receive the drug. In the obesity group, 361 people were prescribed the medication, and 20 developed NAION, a seven-fold increase in risk compared to those not on the drug.

Despite these findings, Dr. Rizzo emphasised that because the study was based on existing data, it cannot definitively prove that semaglutide causes NAION. He said, "What it does show is an association between taking semaglutide and developing this condition where you lose vision," adding that larger, randomised clinical trials are needed to confirm the link.

Dr. Andrew Lee, a neuro-ophthalmologist and clinical spokesperson for the American Academy of Ophthalmology, agreed that the study raised important questions but cautioned that it was premature to draw conclusions. He pointed out that people with Type 2 diabetes are already at increased risk of vision problems, including NAION, and noted that other risk factors, such as hypertension and sleep apnea, which are more common in people with obesity, could also play a role. "The study can only generate the hypothesis of a possible link," Lee said.

There have been some anecdotal reports suggesting a connection between weight loss medications and vision problems, including blurred or distorted vision. However, Rizzo noted that it is unclear how semaglutide, or similar GLP-1 weight loss drugs, could cause NAION. The study focused solely on semaglutide, and did not examine other popular weight loss drugs, such as tirzepatide, the active ingredient in Eli Lilly’s Mounjaro.

Dr. Susan Mollan, a consultant neuro-ophthalmologist at University Hospitals Birmingham in the UK, suggested that the potential biological effects of GLP-1 drugs, which also help control blood sugar levels, could cause a paradoxical worsening of diabetic retinopathy in some patients, though more research is needed to understand this mechanism.

Dr. Rizzo advised patients who are concerned about the potential risks of semaglutide to consult their doctor. "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," he said.

Despite the findings, Dr. Shauna Levy, a specialist in obesity medicine at Tulane Bariatric Center in New Orleans, said the study would not change her prescribing habits. "As for now, the risk still seems low," she said.

Novo Nordisk, the pharmaceutical company that manufactures semaglutide, responded to the study in a statement, asserting that the research was insufficient to establish a direct link between the drug and NAION. "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.