Neuro-ophthalmologists at Mass Eye and Ear noticed an unusual cluster of NAION cases in patients taking semaglutide and decided to study it.

Published in JAMA Ophthalmology (2024), the study found roughly 4× higher odds in people with diabetes and about 7× higher odds in people with overweight or obesity.

Important context: it came from a single specialty center, looked backward at existing records, and involved a relatively small number of cases — so it could raise a question but not answer it.

The findings spread quickly through the news, and the alarm was understandable — these are very widely used medications.

But a single study generating a "signal" is the beginning of a scientific conversation, not the end of one. The key was to see whether the pattern held up in much larger groups of people.

Researchers turned to enormous databases. One analysis of more than 100 million patient records found no meaningful increase in NAION among people on these medications.

A separate 37-million-patient study found about 14–15 cases per 100,000 users per year — a rate that was not clearly different from other diabetes drugs.

Across these large analyses, the overall risk stayed below 1 in 1,000 even after five years.

When researchers pooled the available studies together in a 2025 meta-analysis, the result showed no statistically significant increase in risk.

Data drawn from randomized controlled trials — the most rigorous study design — also did not detect a clear link.

Early reports focused almost entirely on semaglutide. But a 2025 analysis found that tirzepatide carried a similar, modest signal in people with type 2 diabetes.

If there is a real effect, this points toward a class-level association rather than a problem unique to one drug. The absolute risk remained low for both.

The picture today: a possible link exists, the evidence is mixed, and the absolute risk is small — especially for people without diabetes or prior eye disease.

Research is ongoing, and recommendations may continue to evolve as more data arrive.

Contact your doctor or seek prompt eye care if you notice any of the following:

• Sudden loss or dimming of vision in one eye

• A blurred, gray, or dark area in your field of vision

• Vision changes that come on quickly and do not go away

Sudden vision loss should always be treated as urgent, regardless of the cause — and regardless of whether you take a GLP-1 medication.

Don't wait to see if it improves on its own. Seek care promptly so the cause can be identified quickly.

• Given my health history, am I in a higher-risk group?

• Does my eye history or any vascular condition change the picture for me?

• Would choosing one medication over another make any difference for me?

• What symptoms should prompt me to call right away?

Manage the conditions that affect your blood vessels — blood pressure, blood sugar, and sleep apnea.

Report any vision changes early, and keep up with routine eye care if you have risk factors for optic-nerve disease.