GLP-1s and Vision Loss: The NAION Signal Explained

⚠️ Emerging Safety Signal

In July 2024, a study in JAMA Ophthalmology found a significant association between semaglutide use and nonarteritic anterior ischemic optic neuropathy (NAION)—a rare condition sometimes described as a "stroke of the optic nerve." This research is being actively investigated by health authorities. Causality has not been established.

What Is NAION?

Nonarteritic anterior ischemic optic neuropathy (NAION) occurs when blood flow to the optic nerve is suddenly reduced or blocked. The result is damage to the nerve that can cause permanent vision loss.

Key characteristics:

Sudden, painless vision loss—usually in one eye
Typically affects central and peripheral vision
Usually occurs without warning
No proven treatment once it occurs
Second most common cause of optic nerve-related blindness in adults

NAION is rare in the general population—approximately 2-10 cases per 100,000 people annually. However, it's more common in people with diabetes, high blood pressure, and sleep apnea.

The JAMA Study: Key Findings

Hathaway et al., JAMA Ophthalmology (July 2024)

16,827 patients • 6-year follow-up • Single academic institution (Mass Eye and Ear)

Type 2 diabetes patients on semaglutide: 4.28× higher risk of NAION compared to non-GLP-1 medications

Overweight/obese patients on semaglutide for weight loss: 7.64× higher risk of NAION

This was the first study to identify a potential link between semaglutide specifically and NAION. The findings prompted immediate attention from the ophthalmology community.

4.28×

Risk in T2D patients

7.64×

Risk in obesity patients

~0.2%

Absolute rate in study

Follow-Up Research

Since the initial JAMA study, additional research has examined this signal:

Danish Nationwide Studies (December 2024)

424,152 Danish patients with T2D • Two independent research teams

Confirmed elevated risk: patients on semaglutide had 2.19× to 2.81× higher risk of NAION compared to other diabetes treatments.

Denmark saw first-time NAION cases nearly double from 67.6 to 148 annually since Ozempic's introduction in 2018.

Absolute risk increase: 1.4 to 2.5 excess NAION events per 10,000 patient-years.

FDA FAERS Analysis (April 2025)

11,558 semaglutide-related reports analyzed

Semaglutide showed significantly higher reporting of vision impairment compared to:

Other GLP-1 receptor agonists (rOR 1.95)
DPP-4 inhibitors (rOR 2.46)
SGLT2 inhibitors (rOR 3.89)
Metformin (rOR 2.23)

417 cases of visual impairment, retinopathy, or ischemic optic neuropathy were identified.

The Causality Question

All researchers studying this signal emphasize: association does not prove causation.

Possible alternative explanations include:

Confounding: People prescribed semaglutide often have diabetes, obesity, and hypertension—all independent NAION risk factors
Rapid blood sugar/pressure changes: Could the metabolic improvements from GLP-1s (rather than the drug itself) trigger NAION in susceptible individuals?
Detection bias: Patients on new medications may be more closely monitored, catching events that would otherwise go unreported

American Academy of Ophthalmology Statement

"This is not the type of study that can show the treatment caused NAION. But, the careful analysis conducted by the Harvard neuro-ophthalmology research team did identify a potential link between semaglutide treatment and NAION. This intriguing finding should inspire more research that will help clarify if semaglutide does cause NAION."

Current recommendation: "At this time, we do not recommend that people stop taking semaglutide."

Who Is Most at Risk?

NAION has known risk factors that may compound any potential drug-related risk:

Known NAION Risk Factors

Diabetes (especially poorly controlled)

High blood pressure

High cholesterol

Sleep apnea

History of heart attack or stroke

"Disc at risk" anatomy (crowded optic disc)

Smoking

Age over 50

If you have multiple risk factors, the potential additional risk from semaglutide may be more clinically significant for you.

What You Should Know

🚨 Seek Immediate Care If:

You experience sudden vision loss in one or both eyes while taking a GLP-1 medication. NAION typically presents as painless, sudden vision loss. Do not wait—this is a medical emergency. See an ophthalmologist immediately.

Current Guidance

Do not stop your medication based solely on this research. Discuss risks and benefits with your doctor.
Report any vision changes to your healthcare provider promptly.
Get regular eye exams if you have diabetes—this is recommended regardless of GLP-1 use.
If you develop NAION while on semaglutide, discuss with your doctors (ophthalmologist, endocrinologist, PCP) whether to continue the medication.

The Bigger Picture

Context matters when evaluating this risk:

Absolute risk remains low: Even with elevated relative risk, the Danish data suggests only 1.4-2.5 excess cases per 10,000 patient-years
Tens of millions use these medications: With such widespread use, even rare events will generate many reports
GLP-1s have proven benefits: Cardiovascular protection, weight loss, diabetes control—these benefits are well-established
Research is ongoing: Health authorities are actively investigating this signal

Sources

JAMA Ophthalmology. "Risk of Nonarteritic Anterior Ischemic Optic Neuropathy in Patients Prescribed Semaglutide" (July 2024). University of Southern Denmark studies (December 2024). BMC Medicine/FDA FAERS analysis (April 2025). American Academy of Ophthalmology statement (July 2024).

The Bottom Line

Emerging research has identified a potential association between semaglutide and NAION, a rare eye condition that causes sudden vision loss. The July 2024 JAMA study found 4-7× higher risk in semaglutide users, and subsequent studies have supported an elevated risk (though smaller in magnitude). However, causality is not established, and the absolute risk increase appears small—roughly 1-2.5 extra cases per 10,000 patient-years. Major ophthalmology organizations do not currently recommend stopping semaglutide based on this data. If you experience sudden vision loss while on a GLP-1 medication, seek immediate ophthalmologic evaluation. Discuss your individual risk factors with your healthcare providers.