Does Ozempic Cause Vision Loss? What the NAION Research Actually Shows

“Blindness cases have doubled on GLP-1s” is the kind of clip that travels fast. If you take Ozempic, Wegovy, Mounjaro or Zepbound, it is reasonable to want the full context before you decide anything. I sat down with registered dietitian Ana Reisdorf on the GLP-1 Hub podcast to walk through what the research on GLP-1 medications and vision loss actually shows. This article is the written version of that conversation, with the sources.

Educational only, not personal medical advice. Sudden loss of vision in one or both eyes is an emergency: seek same-day care.

What is NAION?

NAION stands for non-arteritic anterior ischemic optic neuropathy. The simplest way to think about it is a stroke of the optic nerve in one eye. Blood flow to the front of the optic nerve drops, the nerve is starved of oxygen, and vision is lost in that eye. The classic story is someone who wakes up and cannot see well out of one eye.

“Non-arteritic” means the artery itself is not inflamed (that is a different condition, giant cell arteritis). The problem is perfusion: not enough blood and oxygen reaching the nerve. Vision loss can be partial or complete. Some people regain part of their vision over months; some do not. There is no proven treatment once it has happened, which is why understanding risk and prevention matters.

How rare is NAION?

NAION existed long before GLP-1 medications. It is uncommon: roughly 2 to 10 cases per 100,000 people per year, mostly in adults over 50. At the high end, that is about 1 in 10,000 people per year.

Who is at risk for NAION?

The risk factors overlap heavily with cardiovascular risk, because NAION is a blood-flow problem:

• Diabetes
• High blood pressure, high cholesterol and established cardiovascular disease
• Obstructive sleep apnea
• Nocturnal hypotension: blood pressure that dips too low overnight
• PDE5 inhibitors such as sildenafil (Viagra) and tadalafil (Cialis), likely because they can lower blood pressure
• A “crowded” optic disc (a small cup-to-disc ratio), plus prior eye surgery or existing eye disease

Notice the overlap: diabetes, obesity, high blood pressure, sleep apnea and heart disease are also the reasons people are prescribed GLP-1s. That overlap is a real source of confounding in the studies below.

What does the research on semaglutide and NAION show?

The 2024 study that started the headlines

A 2024 study in JAMA Ophthalmology from a single neuro-ophthalmology referral center reported a markedly higher risk of NAION in patients prescribed semaglutide: roughly 4 times higher in people with type 2 diabetes and about 7 times higher in people with overweight or obesity.¹ It put the issue on the radar, but it was small, retrospective, and drawn from the exact clinic where unusual optic nerve cases get referred. That selection bias inflates the estimate.

What the larger body of evidence shows

Since then, registry, insurance-claims and pooled analyses have produced mixed results. Some found no association. Some, including studies in veteran populations with many cardiovascular risk factors stacked together, found much higher numbers. Pooled together, the estimates land at roughly twice the background risk, mostly in people with type 2 diabetes taking semaglutide.

Two major reviews agree on that order of magnitude:

• The European Medicines Agency’s safety committee concluded in 2025 that NAION is a very rare side effect of semaglutide, affecting up to 1 in 10,000 people taking it. In adults with type 2 diabetes, it estimated about a two-fold risk, which works out to roughly one additional case per 10,000 person-years of treatment.²
• A 2026 consensus statement from the North American Neuro-Ophthalmology Society and the American Academy of Ophthalmology reviewed the full body of evidence. It described a possible small increase, averaging about two-fold for semaglutide, with causation unproven. It recommended shared decision-making about starting, continuing or stopping treatment.³

All of this is observational data. It can show an association; it cannot prove the drug causes NAION.

Relative risk vs absolute risk: what “double” really means

“Twice the risk” is a relative number. It is accurate, but on its own it misleads. Double a very small number and you still have a small number:

• Background risk: about 1 in 10,000 per year, at the high end
• Doubled: about 2 in 10,000 per year
• Chance of not developing NAION in a given year: still about 99.98%

That does not make the risk zero, and it does not mean nobody should worry. It means the headline number needs its denominator.

Does tirzepatide (Mounjaro, Zepbound) carry the same risk?

We do not know yet. Almost all of the data is on semaglutide, because it has been on the market longest and is the most widely used. My read is that this is more likely a class effect than something unique to semaglutide. If it is driven by what these drugs do to blood pressure, fluid status and blood sugar, the same principles would apply to tirzepatide and newer agents. Expect clearer data on tirzepatide over the next couple of years. The clinical differences between semaglutide and tirzepatide are covered separately.

Why might GLP-1s raise NAION risk?

Nobody has proven the mechanism. I think it is less about the drug doing something toxic to the eye and more about the knock-on effects of rapid change in people who were already at risk. Picture the optic nerve passing through a tight opening, the optic disc. In some people that opening is crowded, like a hose squeezed as it passes through a narrow gap. Anything that lowers the pressure pushing blood through it, or lowers the oxygen in that blood, can tip a borderline nerve into injury.

Plausible contributors on a GLP-1:

• Blood pressure that falls faster than the medications are adjusted. Weight loss lowers blood pressure. If someone stays on the same three or four blood pressure medications, they can end up dizzy, nearly fainting on standing, with even deeper drops overnight.
• Untreated sleep apnea. Repeated overnight drops in oxygen hit a nerve whose blood supply is already limited.
• Dehydration and under-eating. Appetite suppression can lead to too little fluid and food. Some people become dehydrated enough to be hospitalized, which drops perfusion pressure.
• Rapid A1C reduction in diabetes. Fast improvement in blood sugar is known to temporarily worsen diabetic retinopathy, and may similarly stress the small vessels feeding the optic nerve.

The general rule: rapid change is rarely good, even when the change is in the right direction. Gradual weight loss and gradual A1C reduction are safer than dramatic ones.

Questions to ask your doctor if you take a GLP-1

Don’t stop a GLP-1 just because of the headlines. Do bring these to your prescriber and your eye doctor:

1. What does my optic disc look like? An eye exam can show whether you have a small cup-to-disc ratio, a crowded “disc at risk.” If you have diabetes, you should already be seeing an eye doctor regularly.
2. Should my blood pressure medications come down as I lose weight? Track your blood pressure at home and taper with your doctor instead of staying on full doses while you lose weight.
3. Could my blood pressure be dropping at night? If you wake up dizzy or see low morning readings, ask whether to move blood pressure medications away from bedtime.
4. Is my sleep apnea treated and dialed in? GLP-1s can improve sleep apnea, but until it resolves, untreated apnea is a risk factor. Confirm your CPAP or oral appliance is working.
5. Am I eating and drinking enough? Adequate fluids, electrolytes and protein matter on a GLP-1 for this and for preserving muscle.
6. Should I change how I use sildenafil or tadalafil? Using them less, or earlier in the day rather than at bedtime, reduces overlapping blood pressure dips.

Routine eye screening for every GLP-1 user is probably not necessary. If you are worried, or you carry several risk factors, a baseline eye exam is a reasonable step.

Weighing NAION risk against the benefits of GLP-1s

The other side of the scale matters most. In the SELECT trial, adults with established cardiovascular disease and overweight or obesity (without diabetes) who took semaglutide had a 20% lower rate of heart attack, stroke or cardiovascular death.⁴ In absolute terms, that was about 150 fewer major cardiovascular events per 10,000 people over roughly three years of follow-up.

Compare that with roughly one additional NAION case per 10,000 people per year of treatment. For a high-risk patient, the cardiovascular benefit is far larger than the eye risk. For a lower-risk person using a GLP-1 mainly for weight, the balance is closer, and individual risk factors deserve a careful look. Either way, the decision belongs in a conversation with your physician, not in a 20-second clip.

If you develop sudden vision loss while taking a GLP-1, get seen urgently, tell the eye doctor which medication you take, and do not restart it until you have discussed it with your prescriber. European labeling advises stopping semaglutide if NAION is confirmed.²

Want your own risk reviewed?

At Sorrell MD, GLP-1 care includes the parts that matter for this question: home blood pressure tracking and medication tapering, sleep apnea screening, a gradual titration pace, and attention to hydration, protein and muscle. See the Hormone, Body Composition & Metabolic program, or book a free 30-minute call to talk through your situation.

References

1. Hathaway JT, Shah MP, Hathaway DB, et al. “Risk of nonarteritic anterior ischemic optic neuropathy in patients prescribed semaglutide.” JAMA Ophthalmology (2024). DOI: 10.1001/jamaophthalmol.2024.2296

2. European Medicines Agency, PRAC. “PRAC concludes eye condition NAION is a very rare side effect of semaglutide medicines Ozempic, Rybelsus and Wegovy.” June 2025. ema.europa.eu

3. North American Neuro-Ophthalmology Society and American Academy of Ophthalmology. “Glucagon-like peptide-1 receptor agonists and the risk of non-arteritic anterior ischemic optic neuropathy: a consensus statement.” 2026. aao.org

4. Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. “Semaglutide and cardiovascular outcomes in obesity without diabetes.” New England Journal of Medicine (2023). DOI: 10.1056/NEJMoa2307563