People using popular weight-loss jabs Ozempic and Wegovy may be at higher risk of developing an eye condition that can cause blindness, according to a new study.
Semaglutide is the active ingredient in injections used to treat diabetes and prescribed to help people lose weight.
People with diabetes prescribed semaglutide were more than four times more likely to be diagnosed with a condition called non-arteritic anterior ischemic optic neuropathy (NAION), the study found.
Meanwhile, people who were overweight or obese prescribed the drugs were more than seven times as likely to develop the condition as those on other weight-loss medicines.
NAION, which is uncommon, happens when blood flow to the optic nerve is reduced or blocked.
People typically suffer sudden vision loss in one eye, without any pain, often noticing the issue when they wake up.
There are no current treatments for NAION and vision often does not improve.
The new study, published in JAMA Ophthalmology, was led by Joseph Rizzo, a professor of ophthalmology at Harvard Medical School in the US.
He said use of the drugs has “exploded” – but in future doctors should discuss the potential risk of NAION with their patients.
However, he stressed that while the study identified an increased risk, it “relates to a disorder that is relatively uncommon”.
NAION is thought to affect 10 out of 100,000 people in the general population.
Prof Rizzo and his colleagues decided to investigate a potential link between semaglutide and NAION last summer after three of their patients – all taking semaglutide – were diagnosed with vision loss caused by NAION in one week.
To investigate possible links, researchers examined data from more than 16,000 patients from Mass Eye and Ear (a Harvard teaching hospital) treated over a six-year period.
They compared patients who had received prescriptions for semaglutide with those taking other diabetes or weight-loss drugs.
Over three years, 8.9% people on semaglutide for diabetes had NAION compared with 1.8% on the other drugs, the researchers found.
In people taking semaglutide for weight loss, 6.7% had NAION compared with 0.8% on other drugs.
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Prof Rizzo said more studies are needed “in a much larger and more diverse population”.
“Our findings should be viewed as being significant but tentative,” he said.
Graham McGeown, honorary professor of physiology at Queen’s University Belfast, said the authors had acknowledged there were limitations to the study.
But he said: “This research does suggest an association between semaglutide treatment and one form of sight-threatening optic neuropathy, but this would ideally be tested in larger studies.
“Given the rapid increase in semaglutide use and its possible licensing for a range of problems other than obesity and type 2 diabetes, this issue deserves further study, but possible drug side-effects always need to be balanced against likely benefits.”
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A spokesman for Novo Nordisk, which makes Wegovy and Ozempic, said there were limitations to the study, adding: “Patient safety is a top priority for Novo Nordisk, and we take all reports about adverse events from use of our medicines very seriously.
“NAION is not listed as a known adverse drug reaction in the Summary of Product Characteristics (SmPC) for the marketed formulations of semaglutide (Ozempic and Rybelsus for type 2 diabetes and Wegovy for weight management) as per the approved labels.”
