A study conducted by researchers from Harvard Medical School suggests that individuals taking semaglutide, a medication used for weight loss under the brand names Ozempic and Wegovy, may have a higher risk of developing a rare eye condition known as non-arteritic anterior ischemic optic neuropathy (NAION). The study analyzed data from approximately 17,000 patients over a six-year period and found that those taking semaglutide for type 2 diabetes were four times more likely to develop the condition, while those taking it for obesity had a seven-fold increased risk.
However, it is important to note that the study does not definitively prove that semaglutide causes the eye condition, and the researchers cannot explain the increased risk or the difference between the two groups. The numbers of patients affected were small.
Semaglutide is marketed by Novo Nordisk and is known to help people with obesity lose more than 10% of their body weight when combined with diet and lifestyle changes. The drug has gained significant attention due to celebrities sharing their weight loss experiences while taking it on social media. Despite being available only to people with type 2 diabetes (Ozempic) and the most obese (Wegovy) through prescription, online pharmacies are selling semaglutide injections with minimal checks on the weight or underlying health of the buyer.
Common side effects of semaglutide include nausea, vomiting, diarrhea, stomach pain, constipation, and a change in vision. The change in vision is listed as one of the more serious potential side-effects for both Ozempic and Wegovy. NAION affects up to 10 out of 100,000 people in the general population and is thought to be caused by reduced blood flow to an optic nerve, which cannot currently be treated.
In the study, 17 cases of NAION were found among type 2 diabetes patients taking semaglutide, compared to six cases among type 2 diabetes patients taking other drugs, and 20 cases among overweight and obese patients taking semaglutide, compared to three cases among overweight and obese patients taking a different drug.
Dr. Joseph Rizzo, an ophthalmology professor at Harvard Medical School, stated that while the findings are significant, they should be viewed as tentative, as future studies are needed to examine these questions in a larger and more diverse population. UK eye experts from the Royal College of Ophthalmologists recommend that patients taking semaglutide be informed of the small risk of developing eye diseases.
Despite the potential risks, the balance of side-effects and benefits should be considered, as the small numbers of patients affected by the eye condition in the study may not accurately represent the wider population. Novo Nordisk, the manufacturer of semaglutide, stated that the study did not take into account factors such as smoking and the duration of diabetes, and there were challenges in accurately coding and identifying cases of the eye condition. The drug is currently being examined in a trial called Focus, which will assess its long-term effects on diabetic retinopathy in type 2 diabetes patients, concluding in 2027.
Professor Graham McGeown, an honorary professor of physiology at Queen’s University Belfast, emphasized that given the rapid increase in semaglutide use and its potential licensing for a range of problems other than obesity and type 2 diabetes, this issue deserves further study. However, possible drug side-effects always need to be balanced against likely benefits.
