Wegovy carries nearly five times the 'eye stroke' risk of Ozempic, FDA data suggest
Do all semaglutide drugs carry the same risk of sudden vision loss? That question has grown more urgent as prescriptions for GLP-1 receptor agonists have surged worldwide. A new analysis published in the British Journal of Ophthalmology suggests the answer is no, and that the differences between formulations may be substantial.
The study examined reports of ischaemic optic neuropathy (ION), sometimes called "eye stroke," submitted to the US Food and Drug Administration's Adverse Event Reporting System (FAERS) between December 2017 and December 2024. ION occurs when blood flow to the optic nerve is interrupted or inadequate, causing sudden vision loss in one or both eyes. While rare, it has recently been linked to GLP-1 receptor agonists, particularly semaglutide.
Parsing 30 million reports by formulation
The researchers analyzed a staggering 30,668,520 adverse event reports. Of these, 31,774 involved semaglutide products. The average age of semaglutide users in the reports was 56, and just over half were female.
Three semaglutide formulations were examined separately: Ozempic (injectable, up to 2 mg weekly, for type 2 diabetes), Wegovy (injectable, up to 2.4 mg weekly, for obesity), and Rybelsus (oral tablet, for type 2 diabetes). The researchers also looked at tirzepatide products (Mounjaro and Zepbound) as comparators.
Despite generating far fewer total reports than Ozempic, which had a four-year head start on the market, Wegovy showed the strongest association with ION. The analysis identified 28 ION reports linked to Wegovy, with odds roughly 75 times higher than background. Ozempic had 47 ION reports with roughly 19 times higher odds. No ION reports were associated with Rybelsus, the oral formulation. And there was no signal with the tirzepatide comparators.
Dose, route, and sex all matter
The pattern points toward dose and route of administration as key variables. Wegovy is the highest-dose semaglutide on the market at 2.4 mg weekly, compared with Ozempic's maximum of 2 mg. Both are injectables, which are faster-acting than tablets. The absence of any ION signal with Rybelsus, an oral formulation with slower absorption, supports the hypothesis that speed and magnitude of drug delivery influence risk.
The sex difference was equally striking. The highest signal appeared in men taking Wegovy, with odds 116 times greater than background. For Ozempic, the strongest signal was in women, with nearly 27 times greater odds. Overall, the odds of ION were more than three times higher in men than in women across semaglutide products.
The researchers propose several possible mechanisms. High-dose injectable semaglutide may predispose patients to optic nerve hypoperfusion, or low blood supply, through intravascular volume contraction, low blood pressure with nocturnal dips, and autonomic instability. But they are careful to note that no direct clinical link has been established.
The limitations are substantial
FAERS data have well-known weaknesses. Reports are voluntary, not verified, and do not include clinical details about co-existing conditions, disease severity, or other medications. The system cannot determine true incidence rates, only signal strength relative to other reported events. Media attention around Wegovy may have increased reporting for that product specifically, inflating its apparent signal.
The researchers could not assess whether ION reports clustered following specific regulatory actions or media coverage. They also lacked information about patient weight, body mass index, rate of weight loss, or other factors that might independently affect optic nerve blood supply.
These are serious limitations that prevent causal conclusions. What the study provides is the first evidence of a formulation-and dose-dependent pattern in ION risk among semaglutide products, a signal strong enough to warrant prospective studies designed to establish or rule out a causal relationship.
A growing user base raises the stakes
The authors of a linked commentary note that anti-obesity medications are increasingly being considered as first-line treatments for cardiovascular diseases and even dementia, which would further expand their use. The UK already has the highest obesity rate in Western Europe, with 29% of adults classified as obese. The growing use of these drugs in children over age 12 adds another dimension of concern, as potential ocular complications could accumulate over longer lifetimes of exposure.
Recent clinical studies have also suggested that GLP-1 agonists may benefit conditions like age-related macular degeneration and uveitis. The emerging picture is one where these drugs may help some eye conditions while potentially increasing the risk of others. For ophthalmologists and prescribers, the practical question is how to weigh a rare but serious risk against well-documented metabolic benefits.