Semaglutide's link to blinding disease (NAION)

We explore the link between blinding disease/vision loss and Semaglutide, as reported by medical research.

GLP1.Guide Staff

Oct 25, 2024 — 6 min read

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GLP1 Receptor Agonists (Ozempic, Mounjaro, Wegovy, Zepbound and others) are well researched and proven to be effective on type 2 diabetes and weight loss, for most people.

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Don't know what a GLP1 Receptor Agonist is, or how drugs like Ozempic, Mounjaro, Wegovy, or Zepbound work?

Check out our quick explainer

One of the great things about research is that it also examines the negative side effects that occur.

GLP1s are not miracle drugs and have negative side effects, and when this is the case, knowledge is important.

What is Blinding Disease/NAION?

"NAION" stands for Non-arteritic anterior ischemic optic neuropathy (NAION).

NAION is a condition characterized by vision loss due to lack of blood flow to the eyes.

While the root cause isn't quite known/exact, there are many paths and blood supply along with bodily reactions to drugs are prominent theories on causes – even Sleep Apnea is cited as a potential cause.

What link between GLP1s and NAION was discovered?

While the discovery has been in the news for months at this point, there is one paper being primarily published in JAMA, and viewable on PubMed:

This study concluded that although there was not enough data to suggest a causal link (there rarely is, for complex issues), they did find that people who were on Semaglutide were more likely to develop NAION:

NAION occurred in 17 patients in the semaglutide cohort vs 6 in the comparative cohort. The median (IQR) age was 57 (49-63) years for the semaglutide cohort and 58 (47-66) years for the nonsemaglutide cohort.

Given the benefits of Semaglutide, this is certainly a surprising downside, and worth considering for those who are interested in the progression and safety of the drugs.

Reaction from the Opthamology community

What hasn't been covered so much, is the follow up by the American Academy of Opthamology and North American Neuro-Opthamology Society (AAONANO?) – reductively you can think of this as "a society of eye specialists":

Boiling down the important points in their response:

Though NAION is new, changes in vision is a well known side effect of Semaglutide
Semaglutide can also cause worsening of diabetic retinopathy (this is highly counter-intuitive)
Changes in sugar levels in the body can cause changes in the size of the eye, which causes blurry vision.
They do not recomend stopping a prescription of Semaglutide because of this, except in the case of vision loss.

Their response showed impressive restraint and thoroughness, noting the parts of the study that were somewhat weak (e.g. cohort selection) and the clear results that were obtained.

To summarize, this group of Opthamology experts agreed with the researchers in that the best way to refute or add to the information is with larger follow up studies, but they did not sound the alarm with regards to Semaglutide.

A surprising irony in the comparison with Glaucoma

It turns out that NAION is the second most common cause of blindness due to optic nerve damage – the first being Glaucoma:

Our main finding is that prescribed semaglutide is associated with an increased risk of NAION. Despite extensive study, the pathogenesis of NAION has not been fully eludicated.¹²^,¹³ The incidence of NAION is 2 to 10 cases per 100 000 persons,²^,¹⁴ making it the second most common cause of blindness due to optic nerve damage (with glaucoma being the most common).

One of the leading causes of Glaucoma is Diabetic Retinopathy:

Essentially this is a loss of vision that is caused as a knock-on effect of diabetes, which is exactly the disease that GLP1s are most effective on and intended for.

So while it may seem like steering clear of GLP1s could reduce the risk of a vision loss to zero, avoiding diseases like diabetes may take priority.

This is of course mentioned by the researchers in the JAMA paper:

As with any drug, however, therapeutic benefits are inseparable from adverse effects. Related to vision, patients with diabetic retinopathy who received semaglutide incurred a higher risk of exacerbation of the retinopathy, especially with rapid reduction in hemoglobin A_1c levels,²² and a higher rate of progression of proliferative retinopathy and risk of new-onset macular edema.²³

As always, it's important for patients struggling with these issues to consult a medical professional (preferably their own personal doctor) and figure out what is right for them.