Patients using popular weight-loss drugs and related diabetes medications may face a heightened risk for a severe eye condition, according to new study findings.

Published in JAMA Ophthalmology, researchers highlighted an increased incidence of nonarteritic anterior ischemic optic neuropathy (NAION) among users of Wegovy, Ozempic, and Rybelsus—all of which contain the active ingredient semaglutide and belong to the GLP1 receptor agonists class.

The study found that 8.9% of type 2 diabetes patients taking semaglutide experienced NAION, compared to 1.8% of those on non-GLP-1 diabetes drugs. For patients using semaglutide for weight loss, the incidence was 6.7%, versus 0.8% for those on other weight reduction treatments.

Conducted over 36 months and involving 710 patients with diabetes and 979 weight-loss patients, the study linked semaglutide to a fourfold and sevenfold increased risk of NAION in patients with diabetes and obese patients, respectively, even after accounting for other risk factors like high blood pressure and sleep apnea.

NAION, which stems from inadequate blood flow to the optic nerve and can cause sudden vision loss, is more common in older adults. The American Academy of Ophthalmology noted an incidence of 0.54 per 100,000 in the general U.S. population, increasing significantly with age.

Despite these findings, Novo Nordisk contended that the study's design—non-randomized and observational—failed to definitively prove that GLP-1 receptor agonists cause NAION. The company asserted that the condition is not a recognized adverse reaction in the approved formulations of semaglutide.

Experts like Graham McGeown of Queen's University Belfast, who was not involved in the study, acknowledged the research's quality and suggested the need for larger studies to confirm the associations. With the growing use of semaglutide for various medical conditions, further investigation into potential side effects is warranted.