Weight-loss drug linked to rare eye condition

People prescribed semaglutide, sold as Ozempic or Wegovy, for weight loss may be at higher risk of developing a serious but rare eye disease, a study suggests.

After analysing 17,000 patients over a six-year period, US researchers found that those taking medication to treat type 2 diabetes were four times more likely to be diagnosed with the disease than those who were not.

Among people taking it for obesity, the risk of the disease was seven times higher.

But the researchers could not prove that semaglutide caused the eye disease, which can lead to loss of vision in one eye, and could not explain the increased risk or the difference between the groups. The number of people affected was small.

Novo Nordisk, which makes the drug, said patient safety was its “top priority” but that the study had a number of limitations.

Trials have shown that semaglutide can help obese people lose more than 10% of their body weight if they also change their diet and lifestyle.

The drug has become a hot topic after celebrities began posting on social media about the dramatic weight loss they experienced while taking it.

Despite the fact that semaglutide injections are only available without a prescription for people with type 2 diabetes (Ozempic) and those who are obese (Wegovy), online pharmacies are selling it with little or no check on buyers’ weight or underlying health conditions.

All medications have potential side effects.

The most common forms of semaglutide include:

Vision changes are listed as one of the more serious potential side effects in both Ozempic and Wegovy patient safety information.

Nonarteritic anterior ischemic optic neuropathy (NAION) affects up to 10 people per 100,000 in the general population, Harvard Medical School researchers report in JAMA Ophthalmology.

It is thought to be caused by reduced blood flow to the optic nerve and is currently untreatable.

“Our findings are important but should be considered preliminary,” said Dr. Joseph Rizzo, a professor of ophthalmology at Harvard Medical School. “Further research is needed to explore these questions in larger, more diverse populations.”

Eye experts from the Royal College of Ophthalmology recommend that patients taking semaglutide be informed of the small risk of developing eye disease.

Because the study included a small number of people with eye disease (who may not have taken their medications as prescribed or may not be representative of the broader population), the risk statistics may not be accurate.

Novo Nordisk said the study did not take into account whether patients smoked or how long they had diabetes, and it was difficult to accurately classify and identify cases of eye disease.

“NAION is not listed as a known adverse drug reaction for the marketed semaglutide formulations Ozempic, Ryvelsus and Wegovy,” the spokesperson said.

“Semaglutide has been studied in large real-world evidence studies and a robust clinical development programme.”

The drug is also being tested in a trial called “FOCUS”, due to finish in 2027, to evaluate its long-term effects on diabetic retinopathy, an eye disease in people with type 2 diabetes.

Graham McGeown, emeritus professor of physiology at Queen’s University Belfast, said: “Given the rapid increase in use of semaglutide and its potential approval for a range of conditions beyond obesity and type 2 diabetes, this issue merits further study, but the expected benefits of a drug always need to be weighed against the potential side effects.”