Patients using Wegovy for weight loss may face a significantly elevated risk of sudden vision loss compared to those prescribed Ozempic for type 2 diabetes, according to a new study published in the British Journal of Ophthalmology. Researchers found that individuals taking the higher dose of semaglutide found in Wegovy had a fivefold greater chance of developing non-arteritic anterior ischemic optic neuropathy (NAION), a condition often referred to as an “eye stroke,” than those using Ozempic.
The findings add to a growing scrutiny of GLP-1 receptor agonists – a class of drugs including semaglutide (marketed as Wegovy, Ozempic, and Rybelsus) and tirzepatide (Mounjaro) – which have gained widespread popularity for both diabetes management and weight loss. While these medications have demonstrated benefits in regulating blood sugar, reducing appetite, and even lowering the risk of cardiovascular events, emerging safety concerns are prompting closer examination by regulatory bodies and medical professionals.
NAION occurs when blood flow to the optic nerve is disrupted, leading to sudden, often permanent vision loss. Though relatively rare, affecting approximately one in 10,000 people taking semaglutide, the study suggests a “potential dose-dependent safety concern,” meaning the risk may increase with higher dosages. The research, conducted by Canadian researchers, analyzed reports of adverse events submitted to the U.S. Food and Drug Administration (FDA) between December 2017 and December 2024.
The study compared reports associated with up to 2mg of weekly injectable Ozempic, used for type 2 diabetes; up to 2.4mg of weekly injectable Wegovy, approved for obesity – representing the highest currently approved dose – and a daily Rybelsus tablet, also for type 2 diabetes. Researchers also examined reported side effects from tirzepatide (Mounjaro). Wegovy demonstrated the strongest association with sudden vision loss, while no increased risk was observed with Rybelsus or tirzepatide.
Dose and Delivery May Play a Role
Dr. Edward Margolin, from the department of ophthalmology at the University of Toronto and a co-author of the study, believes NAION is likely a “real side-effect” of semaglutide. He suggests that faster or more aggressive weight loss could potentially “increase the risk” of developing the condition. The researchers theorize that the higher doses of Wegovy and the faster-acting nature of injections may contribute to the increased association, while the slower absorption of the Rybelsus tablet may explain the lack of a detectable link.
Regulatory agencies have taken notice. In February, the UK Medicines and Healthcare products Regulatory Agency (MHRA) issued a drug safety update warning about the potential risk of NAION associated with semaglutide. This followed similar warnings from the European medicines regulator. Dr. Alison Cave, the MHRA chief safety officer, emphasized that “the risk of NAION in patients prescribed semaglutide is extremely low,” but stressed the importance of awareness among both patients and prescribers regarding potential symptoms to ensure prompt treatment if they occur.
Study Limitations and Ongoing Monitoring
Samantha Mann, a consultant ophthalmologist and diabetic eye screening lead at the Royal College of Ophthalmologists, cautioned that the study relied on reported side effects and therefore cannot definitively prove a causal relationship or determine the true prevalence of the issue. “An increase in this form of optic nerve ‘stroke’ has however not been widely observed in routine clinical practice at St Thomas’ in London, where I work,” she noted, highlighting the demand for further research to clarify the potential risk.
Novo Nordisk, the manufacturer of Wegovy, Ozempic, and Rybelsus, stated that patient safety is their top priority and that they are closely monitoring the safety profile of their products in collaboration with regulatory bodies worldwide. The company has updated EU patient leaflets to include information about NAION, but maintains that the available evidence does not establish a causal link between semaglutide and the condition, and that the benefit-risk profile of the drug remains favorable.
The findings underscore the importance of a thorough discussion between patients and their healthcare providers regarding the potential risks and benefits of GLP-1 receptor agonists, particularly when considering Wegovy for weight management. Continued monitoring and further research are crucial to fully understand the potential for adverse events associated with these increasingly popular medications.
As research continues and more data becomes available, a clearer picture of the long-term safety profile of these medications will emerge. Patients should remain vigilant for any changes in vision and promptly report any concerns to their doctor.
Disclaimer: This article provides informational content and should not be considered medical advice. Always consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
