Does Ozempic Cause NAION? Exploring the Link and Potential Risks

According to the European Medicines Agency, non-arteritic anterior ischemic optic neuropathy (NAION) is a "very rare" side effect of semaglutide medicines, including Ozempic. While this association has been noted, particularly following recent studies, the absolute risk for individuals remains extremely low.

Quick Summary

Studies suggest a potential link between Ozempic and the rare eye condition NAION, causing sudden vision loss, but a direct causal link is unproven and the overall risk is very low.

Key Points

• Recent Findings: Studies suggest a potential link between Ozempic and an increased risk of NAION, but the absolute risk is very low.

• NAION Defined: NAION is a condition caused by blocked blood flow to the optic nerve, leading to sudden, often permanent vision loss.

• Association vs. Causation: While an association has been observed, a direct causal link between Ozempic and NAION has not been definitively proven.

• Exacerbating Factors: Patients on Ozempic often have pre-existing risk factors for NAION, such as diabetes, hypertension, and sleep apnea.

• Other Visual Effects: Temporary blurry vision can occur due to rapid blood sugar changes, and worsening diabetic retinopathy is another possible side effect.

• Emergency Action: Patients experiencing sudden vision changes should seek immediate medical attention.

What is NAION?

Non-arteritic anterior ischemic optic neuropathy (NAION) is a serious eye condition that can lead to sudden, irreversible vision loss. Sometimes called an "eye stroke," it occurs when blood flow to the optic nerve is reduced or blocked. The optic nerve is the critical cable that transmits visual information from the eye to the brain. When its blood supply is compromised, the nerve can be damaged permanently, resulting in vision impairment.

Symptoms of NAION typically include:

• Sudden, painless vision loss, usually in one eye
• A dark or gray area in the field of vision, often affecting the upper or lower half
• Changes in color perception (dyschromatopsia)
• Loss of peripheral (side) vision
• Blurry or hazy vision

The Evidence Linking Ozempic to NAION

Several recent studies have investigated a potential association between Ozempic (semaglutide) and NAION, especially given the widespread use of GLP-1 agonists for diabetes and weight loss.

Observational Studies

In 2024, a study published in JAMA Ophthalmology drew significant attention to the potential link. Researchers found that among patients with diabetes, semaglutide users had a higher incidence of NAION compared to those not on the medication. Similar findings were noted for patients using the drug for weight loss. Separately, two large cohort studies in Denmark and Norway reinforced the association, suggesting Ozempic users faced a higher risk of developing NAION compared to those on other diabetes treatments.

Regulatory and Expert Consensus

Despite these findings, both regulatory bodies and ophthalmologists emphasize that the absolute risk of NAION is very low. In 2025, the European Medicines Agency (EMA) concluded that NAION is a very rare side effect and recommended that the product information for semaglutide medicines be updated. The World Health Organization (WHO) also issued a safety alert due to the serious nature of NAION and the medication's global use. Experts caution against interpreting the observed association as definitive causation and note that large-scale, randomized controlled trials are needed to confirm a direct causal link.

Possible Mechanisms Behind the Association

Researchers are still investigating exactly how GLP-1 agonists might contribute to NAION. Several theories have been proposed, none of which are yet proven:

• Rapid Metabolic Changes: A common theory suggests that rapid improvements in blood sugar control, especially when beginning treatment, can temporarily affect the eye's blood vessels and lead to vision changes. A similar phenomenon is observed in some diabetic patients achieving rapid glucose control.
• Vascular Effects: GLP-1 receptors are found throughout the body, including the eyes. It's theorized that semaglutide may influence vascular health and potentially impact blood flow to the optic nerve in susceptible individuals.
• Existing Risk Factors: It is important to remember that patients taking Ozempic often have pre-existing risk factors for NAION, such as diabetes and hypertension. These conditions on their own increase the risk of eye complications.

NAION Risk Factors: Beyond the Medication

NAION is not exclusively linked to GLP-1 medications. Many individuals with this condition have other pre-existing risk factors that damage blood vessels and impair blood flow. These include:

• Diabetes
• Hypertension (high blood pressure)
• Hyperlipidemia (high cholesterol)
• Obstructive sleep apnea (OSA)
• A specific, crowded optic nerve anatomy known as a "disc at risk"
• Smoking

Other Ozempic-Related Eye Problems

Besides NAION, Ozempic has been associated with other vision-related side effects:

• Temporary Blurred Vision: Changes in blood sugar can affect the shape of the eye's lens, leading to temporary blurred vision. This usually subsides within a few months.
• Diabetic Retinopathy: Some studies, including the SUSTAIN-6 trial, have shown a paradoxical worsening of diabetic retinopathy in patients with pre-existing conditions, likely due to rapid improvements in glucose control.
• Macular Complications: Macular edema, a build-up of fluid in the macula, has also been reported in a small number of patients.

Comparison of Visual Side Effects

Feature	NAION	Temporary Blurred Vision	Worsening Diabetic Retinopathy
Cause	Blocked blood flow to the optic nerve	Rapid fluctuation of blood sugar levels	Rapid blood sugar control in those with pre-existing condition
Onset	Sudden, often upon waking	Typically occurs during the first few months of treatment	Usually within months of starting or escalating dose
Severity	Potentially permanent, irreversible vision loss	Temporary and generally mild, resolves over time	Can lead to vision loss, requires ophthalmologist monitoring
Action	Immediate medical attention required	Often resolves on its own; monitor with a healthcare provider	Regular eye exams are crucial; consultation with an ophthalmologist

Navigating the Risks: What Patients Should Know

For most individuals, the benefits of Ozempic for managing type 2 diabetes and promoting weight loss are substantial and outweigh the very low risk of developing NAION. However, staying informed and proactive is key, especially for those with existing eye conditions or other risk factors.

Here are steps patients can take:

• Discuss with Your Doctor: Talk to your prescribing physician about all your health risks and needs before starting or stopping any medication.
• Inform Your Ophthalmologist: Let your eye doctor know you are taking Ozempic, especially if you have a history of diabetic retinopathy. Regular eye exams are highly recommended.
• Recognize Symptoms: Be aware of the symptoms of NAION and other vision changes.
• Seek Immediate Help: If you experience any sudden vision changes, including blurred vision, a dark spot, or visual field loss, contact your doctor or an ophthalmologist immediately. Early diagnosis and management of underlying risk factors are crucial.

Conclusion

While a potential link has been identified between Ozempic and the rare eye condition NAION, it's essential to put this risk in proper perspective. The absolute risk for any one individual remains very low, particularly when compared to the well-established benefits of semaglutide for diabetes and cardiovascular health. The connection appears to be an association rather than a proven causal link, and many patients on Ozempic have pre-existing risk factors that also increase their likelihood of developing NAION. Informed communication with healthcare professionals and diligent eye health monitoring are the most important steps for any patient concerned about their vision while using Ozempic.

Learn more about NAION from the American Academy of Ophthalmology at aao.org.

Frequently Asked Questions

What is NAION?

NAION is a rare eye condition caused by a reduction or blockage of blood flow to the optic nerve. It is often referred to as an "eye stroke" and typically results in sudden, painless vision loss in one eye.

Does Ozempic directly cause NAION?

Current research shows an association between Ozempic (semaglutide) and NAION, but a direct causal link has not been definitively proven. The absolute risk remains very low, and many patients have other NAION risk factors like diabetes and hypertension.

What are the symptoms of NAION?

Symptoms of NAION can include sudden, painless vision loss in one eye, blurred or dim central vision, loss of peripheral vision, and seeing a dark or gray area in your visual field.

Does vision improve if I stop taking Ozempic after developing NAION?

Vision loss caused by NAION is often permanent, and stopping Ozempic will not reverse the damage. Early medical intervention for the NAION itself is critical to manage the condition.

What other vision problems are linked to Ozempic?

Other vision issues linked to Ozempic include temporary blurry vision due to blood sugar changes and a temporary worsening of pre-existing diabetic retinopathy, especially in the early stages of treatment.

Should I be concerned about NAION if I am taking Ozempic?

The risk of developing NAION from Ozempic is considered very low. However, individuals with existing risk factors, such as diabetes, high blood pressure, or a history of diabetic eye disease, should discuss their concerns with a doctor.

What should I do if I experience sudden vision changes while on Ozempic?

If you experience any sudden vision changes, including blurriness, a dark spot, or loss of vision, you should contact your healthcare provider or an ophthalmologist immediately for evaluation.