NAION Occurs in about 1 in a thousand

lessthanhalf

lessthanhalf

Explorer
Joined
Jun 27, 2025
Messages
1,124
Reaction score
972
Location
melbourne
About 1 out of every 1,000 semaglutide users develops nonarteritic anterior ischemic optic neuropathy (NAION).

Sadly, only the abstract is available

Glucagon-like Peptide-1 Receptor Agonists and Risk of Nonarteritic Anterior Ischemic Optic Neuropathy

Systematic Review and Meta-Analysis https://www.neurology.org/doi/10.1212/WNL.0000000000214864

I had somehow assumed this was considerably rarer. Yet 118 cases per 100,000 among semaglutide users isn't all that uncommon. This research only addresses incidence for semaglutide and older drugs, not newer ones, though semaglutide will have stronger data given its longer presence on the market. Based on other reports I've come across, tirz or reta might carry a lower risk, but not by a huge margin.

If someone is taking GLP's for lifelong severe obesity, a 1/1000 risk of vision loss in one eye is likely a reasonable trade-off, but what about bodybuilders? I previously figured this was a concern at something closer to 1 in ten thousand or 100 thousand, but at these odds it genuinely warrants consideration.
 
An abstract alone gives you very little to work with, yet my reading is that the elevated risk sits with diabetic users of GLP-1RAs. Is that how you took it?
 
After seeing this result, I couldn't quite accept it — even with the enormous figures cited — so I checked what I could find on google scholar and went over it with chatgpt.

The odds varied considerably from one study to another, according to that review, which implies the figures may not be as alarming as they look. On top of that, most of the many studies on google scholar had only single digit citation counts, so judging which findings are considered trustworthy is difficult. Reported results ranged all the way from no increase up to roughly one in a 1000.

Older age, diabetes, sleep apnoea, high blood pressure and vascular disease all make NAION more likely. That leaves plenty of scope for confounding variables, since a lot of those conditions are tied to obesity or diabetes — which raises the chance of being prescibed GLP's, and also the chance of getting NAION — so pinning down causation becomes harder.

One thing it does imply is that for younger people who are less overweight and using GLP drugs, the risks are smaller than for those with diabetes, more severe obesity, or obesity plus health complications who use GLP drugs. Still, it gives little sense of what those risks actually amount to in the less overweight group.

For someone who is only a bit overweight, what counts as an acceptable risk of blindness in an eye?
 
From what I gather, the relative risk rises quite a bit, yet the absolute risk remains tiny. Everybody carries some chance of getting it, though that chance is very low. Even if that chance were doubled (as has been proposed), it would still be very low. So for someone already at higher risk, it might move from 1% to 2%. For someone at low risk, it could look more like .1% to .2% (just an example, I haven't come across anything about what the risk is in healthy people). That means a person who is very healthy may not be adding much risk for the benefit.
 
Broadly speaking, I believe AION—NAION included—shows up at a rate of roughly 10 per 100,000, which lines up with the 1 in 10,000 figure you mentioned.

This paper looks at overweight patients with and without diabetes who were given semaglutide


https://jamanetwork.com/journals/jamaophthalmology/fullarticle/2820255


When it comes to what level of risk is acceptable, that's difficult to pin down. Still, I hope sharing this information allows people to make well-informed choices
 
I’d like to know more about when NAION shows up relative to beginning a GLP. Back when I first read about this, one idea was that blood sugar dropping quickly might play a role, and I’d figure that kind of risk would cluster early on, maybe even dipping under the pre-treatment baseline.

Last month I ran into my eye doctor outside of work and asked whether I had any risk factors that raise the odds of NAION.

From what I can tell, it mostly comes down to luck.
 
Back
Top