A recent analysis suggests the high-dose semaglutide product Wegovy may be associated with an elevated reporting rate of ischemic optic neuropathy (ION), a rare but serious cause of sudden vision loss sometimes called an “eye stroke.” The signal was strongest for Wegovy and appeared notably more pronounced in men compared with other semaglutide formulations.
Study and methods
Researchers reviewed more than 30 million records from the U.S. FDA’s public adverse-event reporting system covering late 2017 through 2024. That database contains voluntary reports from patients, clinicians and manufacturers about suspected medication side effects. The team isolated reports in which a GLP-1 receptor agonist was suspected in cases of ischemic optic neuropathy and analyzed each semaglutide formulation separately. They also examined tirzepatide and common diabetes drugs such as metformin and insulin for comparison, adjusting statistical analyses for age and sex to detect disproportionate reporting.
Key findings
– About 31,000 reports in the dataset mentioned semaglutide.
– Wegovy, the higher-dose weekly injection approved for obesity, showed the strongest association with reported ION events, even though it had fewer total reports than Ozempic (a lower-dose weekly injection for type 2 diabetes).
– Oral semaglutide (Rybelsus) had no reported ION cases in this review; its slower and lower absorption was highlighted as a possible reason.
– Tirzepatide did not show a significant association with ION, and neither metformin nor insulin showed increased reporting of optic nerve ischemia.
Interpretation and possible mechanisms
Investigators propose that higher systemic exposure and the faster, larger weight loss seen with Wegovy could affect blood flow to the optic nerve. Hypothesized mechanisms include reduced optic nerve perfusion related to rapid fluid loss, drops in blood pressure (particularly nocturnal hypotension), and vascular changes tied to abrupt weight loss. The exact biological pathway linking these drugs to ION is not confirmed.
Limitations
Because the FDA system is based on voluntary reports, it cannot provide true incidence or prove causation. Reporting biases, variable clinical detail, and inability to verify every case limit definitive conclusions. The observed pattern nonetheless raises concern and warrants further study.
Clinical context and recommendations
Outside experts emphasize context: untreated obesity, diabetes and vascular disease remain far more common threats to vision than this potential drug-associated risk. Still, clinicians and patients should be mindful of precautions when prescribing or using high-dose semaglutide:
– Monitor patients for visual symptoms and consider baseline and regular eye exams, especially in people with diabetes or vascular risk factors.
– Start at lower doses and titrate slowly in patients with multiple health issues rather than escalating rapidly.
– Avoid extremely rapid early weight loss by moderating calorie reduction and focusing on gradual, sustained change.
– Maintain hydration and be attentive to symptoms of low blood pressure, particularly nocturnal hypotension.
– Use these medications under the supervision of experienced clinicians, following approved dosing instructions rather than self-titrating.
Next steps
The authors call for controlled studies to confirm whether the association is causal, to quantify absolute risk, and to identify which patients are most vulnerable and how best to prevent harm. The study was published March 10 in the British Journal of Ophthalmology and highlights the need to balance the substantial benefits of semaglutide for weight loss and diabetes against rare but serious potential adverse events.