Wegovy linked to rare 'eye stroke' that can cause sudden blindness: new case series published

A new case series conducted by researchers at Harvard Medical School and published in the American Medical Association's JAMA Ophthalmology has identified cases of Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION) — colloquially called 'eye stroke', a rare blockage in the blood supply to the optic nerve — among patients taking the GLP-1 receptor agonist weight-loss drug Wegovy (semaglutide). According to Science Daily's coverage, the study found NAION incidence among Wegovy users roughly four times higher than in a comparable non-using control group.

NAION is a medical condition in which blood flow to the front portion of the optic nerve is suddenly interrupted, resulting in partial — or in rare cases total — vision loss. It is not transient but permanent; patients' sight may not return. In medical literature, NAION incidence in the general population over 50 years of age is reported at 2 to 10 cases per 10,000 people annually. The Harvard study calculated this rate at 9 to 30 per 10,000 among Wegovy users, after adjustments for the age and general health status of the user cohort.

The lead author of the study, Professor Joseph Rizzo, chair of ophthalmology at Massachusetts Eye and Ear, Harvard's ophthalmology department, told Science Daily that 'the absolute risk is small — roughly 9 to 30 in 10,000 patients — but with the medication's global use at around 20 million people, the annual additional cases could be between 18,000 and 60,000.' Rizzo emphasised that the findings are 'not a signal to halt current Wegovy prescriptions but a new element in the risk-factor assessment.'

The mechanism linking NAION to Wegovy is not yet definitive. The Harvard team proposes three hypotheses: (1) semaglutide's specific effects on vascular endothelium may restrict blood flow, (2) rapid weight loss may generate sudden body-fluid-balance shifts that produce transient low pressure in the optic nerve vessels, and (3) the Wegovy user population already has higher rates of diabetes or cardiovascular disease history, which may combine with other contributing NAION factors in a biased selection effect. Rizzo said that 'distinguishing which of these three is dominant requires a prospective controlled study.'

The FDA, in its statement following the JAMA Ophthalmology publication, said it has 'begun systematic evaluation of ocular adverse events for Wegovy and other GLP-1 receptor agonists.' Decisions on boxed warnings or prescribing-information updates will be clarified at the end of the FDA's 90-day review period. The adverse-event reporting system MedWatch has decided to accelerate the manual flagging of ocular complaints originating from GLP-1 users.

Stephen Gough, vice-president of medical affairs at Wegovy's manufacturer Novo Nordisk, told Science Daily: 'we are taking observational data seriously; however, establishing a causal link between NAION and semaglutide requires continued analysis of long-term follow-up data from our Phase 3 trials.' An analytic review of optic neuropathy cases, including NAION, in the company's last three clinical trials (SELECT, STEP-Series, FLOW) is expected to be completed in July.

Ophthalmologists have begun debating what monitoring protocol should be applied to Wegovy patients. Dr Aaron Lee, vice-president of the American Academy of Ophthalmology, told Science Daily that 'an annual fundus examination and visual-field test may be reasonable for patients beginning Wegovy, particularly those over 50 with a history of diabetes or hypertension.' Lee added: 'the ophthalmology community is also weighing the medication's benefits — particularly the 20-per-cent drop in cardiovascular mortality risk observed with Wegovy, which is a significant counterbalance.'

Wegovy and the GLP-1 receptor agonist market in general have grown rapidly over the past three years. Market-research firm Evaluate projects the global GLP-1 market will reach 65 billion dollars in 2026 and exceed 150 billion dollars by 2030. Wegovy is now a product generating roughly 18 to 20 billion dollars in annual sales; in the US market, it maintains its lead in the competition with Eli Lilly's Zepbound (tirzepatide). How the adverse-event reporting will be perceived on the investor side is under monitoring for the next three months.

Limits on the observational study's methodology are also highlighted in the Science Daily piece. Because NAION is a rare condition, even a 12,000-case series produces results with wide confidence intervals. The Harvard study was conducted as a retrospective analysis of electronic health records and does not reach the data quality of a randomised controlled trial for causal inference. JAMA Ophthalmology's accompanying editorial suggests that the results should be treated as 'a hypothesis-generating but yet-to-be-confirmed finding.'

This article is not medical advice. Personal decisions on the use, continuation or discontinuation of Wegovy and other GLP-1 receptor agonists should involve consultation with an endocrinologist or internal-medicine specialist. Patients experiencing a visual disturbance, a sudden loss in the visual field or similar ophthalmological symptoms are advised to consult an eye-care professional urgently.