Study links Ozempic/Wegovy to sight-threatening disorder

Shares in Novo Nordisk and Eli Lilly have been under pressure after a study emerged suggesting that people taking a GLP-1 agonist had an elevated risk of a rare but serious eye condition.

The study published in the journal JAMA Ophthalmology focused on semaglutide, the GLP-1 agonist in Novo Nordisk’s diabetes therapy Ozempic and obesity treatment Wegovy, which has become sought-after for its weight-loss properties.

Novo Nordisk shares tracked down almost 3% after the study was published, while Lilly also fell around 1% in sympathy even though the study did not look at any of its GLP-1 drugs.

Researchers from Harvard and Brigham and Women’s Hospital in Boston found an elevated risk with semaglutide of a condition known as non-arteritic anterior ischaemic optic neuropathy (NAION) that can cause sudden vision loss in the eye leading to long-term visual impairment.

Their observational study looked at registry data involving more than 17,000 Mass Eye and Ear patients treated over the six years since semaglutide was first launched, comparing those taking the drug for type 2 diabetes or weight loss with a matched cohort given non-GLP-1 medications .

They found an imbalance in NAION between the two groups, with 17 cases among diabetic patients taking semaglutide versus six cases among those treating diabetes with other drugs. Similarly, there were 20 cases in overweight and obese people taking the GLP-1 agonist and three in the group taking other medications to lose weight.

The authors acknowledge that the findings are speculative and do not prove causality, but add they could be significant and warrant further study – particularly as the use of semaglutide and other GLP-1 drugs is rising quickly around the world.

“The use of these drugs has exploded throughout industrialised countries and they have provided very significant benefits in many ways, but future discussions between a patient and their physician should include NAION as a potential risk,” according to Harvard Medical School ophthalmology professor Dr Joseph Rizzo, who led the study.

NAION is relatively rare, occurring in up to 10 out of 100,000 people, but is the second-leading cause of optic nerve blindness after glaucoma. It is caused by reduced blood flow to the optic nerve head, generally leading to permanent vision loss in one eye, and has no approved treatment.

Rizzo and his team decided to look into the association after realising that three patients in their practice had been diagnosed in just one week, all of whom had been taking semaglutide.

Novo Nordisk said in a statement that it takes all reports of side effects with its products seriously, but pointed out that the study did not take into account some potentially pertinent information such as how long patients had diabetes or whether they were smokers.

It can be hard to correctly diagnose eye disorders, so some cases recorded as NAION could be other forms of vision loss associated with long-term diabetes. Meanwhile, some studies have suggested smoking is an independent risk factor for NAION, although others disagree.

Queen’s University Belfast honorary professor of physiology Graham McGeown, who was not involved in the study, said it was well-designed and the authors had tried hard to match the study groups for factors that could affect the result, while conceding that had been difficult.

“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.”

GLP-1 agonists have previously been investigated by regulators in the US and Europe for a possible risk of suicide, but no strong evidence for a link was found.

Image by Ghasoub Alaeddin from Pixabay