Is 'Going Blind While Losing Weight' an Exaggeration? The Truth Behind Wegovy GLP-1 Eye Side Effects Simultaneously Warned by Chonnam National University & UK MHRA

One-line hook: In February 2026, simultaneous warnings emerged from both Korea and the UK that Wegovy — hailed as a 'game changer' in weight loss — can, though rarely, cause blindness. Here's why you need to know this right now.

TL;DR

• Chonnam National University College of Pharmacy research team (2026.02.25): Patients newly starting GLP-1 class treatments face a 2.6x higher risk of NAION compared to the control group
• UK MHRA (2026.02.07): Mandatory addition of blindness risk warning language when prescribing Wegovy and Ozempic
• Actual incidence is rare (approximately 18 per 100,000 population), but when it occurs, permanent blindness is possible
• Novo Nordisk maintains that causality has not been confirmed, but a 2027 clinical trial is planned
• Experts say pre-screening and monitoring of high-risk groups — not stopping treatment — is the key

The Facts: What Happened

On February 25, 2026, Professor Noh Yun-ha's research team at Chonnam National University College of Pharmacy released results from a joint analysis of large-scale UK medical big data conducted with McGill University in Canada. The core figures were striking.

• 106,000 patients newly prescribed GLP-1 class treatments vs. 416,000 patients using DPP-4 inhibitors
• Risk of NAION within 1 year of starting treatment: GLP-1 group had a hazard ratio of 2.56 compared to the control group (95% CI 1.44–4.86)
• Actual incidence rate: 18 per 100,000 in the GLP-1 group vs. 7 per 100,000 in the control group
• The increased risk was concentrated within the first 6 months, with a tendency for the gap between the two groups to narrow during long-term follow-up

Also on February 7 of the same month, the UK Medicines and Healthcare products Regulatory Agency (MHRA) officially acknowledged the existence of NAION complications when prescribing semaglutide (Wegovy, Ozempic, Rybelsus) and strengthened safety warnings. It recommended that patients experiencing vision changes immediately visit an emergency ophthalmologist, and made it mandatory to include blindness risk warning language in future prescriptions.

What Is NAION?

Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION)

NAION is sometimes called a 'stroke of the eye.' It is a condition in which blood flow to the optic nerve is suddenly blocked, causing the optic nerve to die.

• Symptoms: Sudden blurring of vision in one eye without pain, or part of the visual field appearing dark. Often discovered upon waking in the morning
• Outcome: Permanent blindness possible if it progresses. The second most common cause of blindness after glaucoma
• Proposed mechanism: GLP-1 drugs may cause a rapid drop in blood sugar, preventing retinal and optic nerve microvasculature from adapting. Alternatively, blood flow changes may directly compress optic nerve blood vessels

Why It's Trending Now

1. Korean big data research release: Discussion previously centered in the West has expanded through Korean research, generating credible evidence for domestic patients
2. Official UK regulatory tightening: The MHRA's announcement making warning labels mandatory elevated this from 'rumor' to 'official risk'
3. Surge in domestic Wegovy prescriptions: Since its domestic launch in October 2023, prescriptions for obesity treatment have exploded
4. Chosun Ilbo Feb. 27 feature: An interview with Dr. Woo Chang-yoon, director of WIM Clinic (formerly an endocrinologist at Asan Medical Center), sparked mass public attention — "There are cases of irreversible damage to eyes and kidneys"
5. Growing US lawsuits: As NAION-related Wegovy class action lawsuits increase in the US, awareness among domestic patients is rising

Background: The Dual Nature of GLP-1

Semaglutide (Wegovy, Ozempic) has been an innovative drug that shook the global pharmaceutical market from 2023 to 2026. Its excellence in controlling diabetes, reducing cardiovascular risk, and achieving weight loss led Time magazine to name it 'Drug of the Year.'

However, side effect controversies have continued:

The European Medicines Agency (EMA) had already warned of the association between GLP-1 drugs and NAION at its June 2025 EMA PRAC meeting and recommended updating prescribing safety information. It also presented an estimate of approximately 1 in 10,000 possible cases.

Outlook: How Long Will This Last?

Regulatory Direction

• Korea's Ministry of Food and Drug Safety is likely to update prescribing guidelines adopting warnings from the UK MHRA and EMA
• Novo Nordisk's 2027 clinical trial results will be the biggest inflection point

Market Impact

• Low likelihood of short-term prescription slowdown: The effects on obesity and diabetes treatment remain overwhelmingly positive, so most experts recommend 'pre-screening' rather than stopping treatment
• Discussion of mandatory ophthalmological examinations before prescribing for high-risk groups (glaucoma, optic nerve disease, obese patients with diabetes) may emerge

Consumer Behavior

• Search volume for 'Wegovy side effects' expected to surge → Increased demand for medical YouTube and blog content
• Potential for substitution demand shifting to Mounjaro (tirzepatide, Zepbound) in the obesity treatment market

Checklist: If You Are Currently Taking Wegovy

Reference Links

• Chonnam National University & McGill University GLP-1 NAION Big Data Research Announcement (OhmyNews, 2026.02.25)
• "Wegovy May Cause Blindness"... UK MHRA Strengthens Warning (Donga Ilbo, 2026.02.07)
• GLP-1 Under Fire Again…Ophthalmic Complications on the Table (Medical Times)
• Wegovy NAION Lawsuit – US Class Action Status (DrugWatch, 2026.02)
• 9% Blindness Rate from Wegovy? That's False…But These People Should Absolutely Not Take It (JoongAng Ilbo)
• Can Ozempic Affect Eye Health? (American Academy of Ophthalmology)

Image Source

• Wegovy semaglutide photo: Wikimedia Commons, CC BY 4.0 (link)