I Take Zepbound. Should the New FDA Eye Warning Worry Me?

I have been on Zepbound for years, and my eyesight has gotten worse due to age. So when the FDA announced on Monday, November 9, that it was requiring a vision-loss warning on every GLP-1 drug, I mostly avoided reading about it. I have been shying away from this story. Silly, but true.

Disclosure: I take Zepbound, and I own Eli Lilly stock, the only pharmaceutical stock I hold.

Here is the answer I went looking for. Slow, gradual change is not how this condition typically shows up. The warning covers a rare kind of sudden vision loss in one eye. The extra risk is small, and most of the evidence is about semaglutide (Ozempic, Wegovy) rather than tirzepatide (Zepbound, Mounjaro).

What the FDA found on GLP-1 vision loss

The condition is non-arteritic anterior ischemic optic neuropathy, NAION for short. Blood flow to the front of the optic nerve drops, vision in one eye goes, and the loss can be permanent. It affects men and women about equally, and the average age at onset is 66.

The FDA pooled 126 randomized trials of GLP-1 drugs, about 134,000 patients, and found 15 probable cases: 10 in people on a GLP-1 drug and 5 on placebo.

Group	NAION cases per 100,000 person-years
GLP-1 users in FDA’s 126 trials	6.4
Comparison patients in the same trials	3.8
General population over 50 (published estimates)	2.3 to 10.2
People with type 2 diabetes starting a diabetes drug (FDA claims study)	26 to 32

The gap between the first two rows works out to about one extra case for every 38,000 years of treatment (my arithmetic). With only 15 cases, treat that as rough. The FDA calls this a “potential increased risk”: enough to require a warning, not proof that the drugs cause NAION. Its review of animal data found no mechanism. Europe’s drug regulator, working mostly from diabetes registries, put it higher for semaglutide: about one extra case per 10,000 person-years, which it still classes as “very rare.”

The last row is a different kind of study in a different population, so it isn’t directly comparable. In FDA’s insurance-claims study, people with type 2 diabetes developed NAION at 26 to 32 cases per 100,000 a year whichever of three drug types they started, well above the general over-50 range; how much of that is diabetes itself, I can’t tell. There, GLP-1 starters had a higher risk than DPP-4 inhibitor starters, but no statistically significant difference from SGLT2 inhibitor starters.

Sudden in one eye vs slowly worse with age

NAION “typically presents as an acute, monocular, painless loss of vision,” per the American Academy of Ophthalmology’s clinical guide: one eye, all at once, no pain. The change most of us notice after 40 is presbyopia, which the academy describes as eyes that “gradually lose the ability to see things clearly up close.” Mine has been the slow kind.

I can’t sort out anyone’s eyes from a blog post. Gradual blurring has causes besides presbyopia, so if your vision is drifting slowly, book an ordinary eye exam and tell the eye doctor which drug you take. The ophthalmologists’ own groups don’t recommend an exam just to screen for NAION before starting a GLP-1, but people with diabetes should keep their regular diabetic eye exams.

Zepbound is on the list, and the data on it is thin

Mounjaro and Zepbound are named in the FDA notice along with every other GLP-1 drug. The 2024 study that prompted the FDA’s review (Hathaway et al., JAMA Ophthalmology) looked only at semaglutide. A 2025 JAMA Network Open study of US health records grouped semaglutide and tirzepatide together, and under 5% of its patients on those drugs took tirzepatide alone. When it compared the two drugs head to head, there were two cases on semaglutide and one on tirzepatide, too few to mean anything.

Lilly told Reuters the FDA notice “does not reference any findings specific to Lilly medicines.” That is true, and it mostly reflects how little tirzepatide data exists. The FDA also says NAION cases have been reported for every GLP-1 drug currently on the market. The academy and the neuro-ophthalmologists’ society wrote this year that “one should not assume that this risk is specific to semaglutide.” I found no evidence that switching from semaglutide to tirzepatide lowers this risk. The obesity doctor Michael Albert wrote up the prescriber’s side this week.

Sudden vision loss is an emergency

The FDA’s list:

• sudden, painless vision loss in one eye, which you may notice when you wake up
• blurred or missing parts of your vision, such as a blind spot or tunnel vision
• colors that look distorted
• blurry or hazy spots in the center of what you see

The FDA says to contact your doctor right away. The neuro-ophthalmologists put it more plainly: “If you notice sudden, painless vision loss, see an ophthalmologist promptly.” I would treat it as an emergency: if you can’t see an eye doctor the same day, go to an emergency room. No treatment has been shown to improve vision after NAION, but a blocked artery in the retina also causes sudden, painless vision loss, and the academy’s EyeWiki reference calls that “an ophthalmic emergency that requires immediate evaluation and transfer to a stroke center.” Over 50, doctors also check for giant cell arteritis, an inflamed-artery condition treated with steroids, so mention any headache, scalp tenderness or jaw pain when you chew.

Don’t stop the drug on your own. If NAION is actually diagnosed, the FDA tells doctors to consider stopping the GLP-1 “unless the benefits of treatment clearly outweigh the risk,” and the ophthalmologists point out that for people with severe obesity, hard-to-control diabetes or heart disease, stopping abruptly “can be riskier than a rare eye event.”

The risk factors you can do something about

Honestly, I couldn’t find evidence that fixing NAION’s risk factors prevents it, and the academy’s clinical guide says that even after a first episode, controlling them hasn’t been shown to protect the other eye. Most are worth fixing for your heart and brain anyway.

Smoking, diabetes, high blood pressure, sleep apnea, anemia and kidney disease are on the FDA’s list. The academy’s guide adds erectile dysfunction pills like sildenafil (Viagra) and tadalafil (Cialis), which have been “associated with an increased risk of NAION,” so if you take one, tell the eye doctor.

Sleep apnea is the one I would act on first. Untreated, it is on both lists, so if you have symptoms or risk factors, ask your doctor whether you should be tested. (Zepbound is approved to treat moderate to severe sleep apnea in adults with obesity.)

An academy spokesperson also named overnight low blood pressure, which “can sometimes be treated by taking blood pressure medications in the morning.” If you take a blood pressure pill at night, ask your doctor whether the timing matters for you; don’t move it on your own.

Without diabetes and without a past NAION, I read this warning as a reason to know what sudden vision loss in one eye looks like, not a reason to stop the drug.