Weight loss drug Semaglutide may increase risk of rare eye condition, study warns

Semaglutide is available as Ozempic for treating type 2 diabetes and as Wegovy for managing overweight and obesity

Amid the rapid rise in semaglutide usage, a study has suggested a potential risk of a rare eye condition associated with the weight loss drug.

Semaglutide, a glucagon-like peptide 1 receptor agonist (GLP-1 RA), is available under the brand name Ozempic (by Novo Nordisk) in a lower-dose form for managing type 2 diabetes mellitus (T2DM), and as Wegovy (also by Novo Nordisk) in a higher-dose form for weight management in patients with high body mass indexes.

Anecdotal evidence has indicated that semaglutide might be linked to nonarteritic anterior ischemic optic neuropathy (NAION).

To investigate this potential connection, researchers in the United States analysed data over a six-year period from nearly 17,000 neuro-ophthalmology patients at Massachusetts Eye and Ear Hospital in Boston, Massachusetts, all of whom had no prior history of NAION.

They wanted to examine whether semaglutide prescriptions were associated with an increased risk of NAION in patients with type 2 diabetes or patients who are overweight or obese.

In a report published in JAMA Ophthalmology on July 3, 2024, the researchers suggested an association between semaglutide and NAION.

They found that the incidence of NAION occurring for the first time over a 36-month period was 8.9 per cent among patients with T2DM who were prescribed semaglutide, compared to 1.8 per cent patients with T2DM who were prescribed other antidiabetic medications.

Among patients who were overweight or obese, the cumulative incidence of NAION was 6.7 per cent in those who were prescribed semaglutide, compared with 0.8 per cent  in the non-semaglutide group.

The authors, however, noted that this was an observational study, and future study is required to assess causality.

NAION is a rare condition characterised by blurring or dimming of vision, resulting from a blockage in the arteries supplying blood to the optic nerves.

It is estimated to affect between 2 to 10 out of every 100,000 people annually in the United States. Currently, there is no available treatment for the condition, and it commonly does not improve over time.

According to the NHS, Wegovy (semaglutide used as weight loss medicine) works by making the patient feel fuller and less hungry. It is taken as an injection once a week.

It is available only through prescriptions from a specialist weight management service. A doctor might recommend it if dietary and exercise modifications alone have not been effective.

The World Health Organization (WHO) recently issued a warning about counterfeit versions of semaglutide found in the UK. Patients were advised to obtain semaglutide treatment only through a healthcare professional and cautioned against purchasing the drug online.