Semaglutide and bilateral NAION

A case report published in BMC Ophthalmology on 10 July 2026 describes a 37-year-old man who developed bilateral optic disc swelling and inferior macular ischaemia after 11 months of semaglutide use^[1]. His right eye lost most of its useful vision (acuity of 6/200) and his left eye was affected to a lesser degree (20/25). After semaglutide was stopped, both eyes recovered substantially within a month, though the authors describe the improvement as partial, not complete.

What happened clinically

The patient was obese with no previously known systemic disease. He had been taking semaglutide for 11 months when he presented to ophthalmology. Examination found optic disc swelling in both eyes and inferior macular ischaemia, along with a relative afferent pupillary defect of 0.9 log units in the right eye^[1]. The clinical picture was consistent with bilateral non-arteritic anterior ischemic optic neuropathy (NAION) and branch retinal artery occlusion. Both conditions reflect compromise of the blood supply to the optic nerve or retinal vessels.

Semaglutide was discontinued. One month later, right-eye visual acuity had improved from 6/200 to 20/30 and the left eye maintained 20/20^[1]. Disc swelling resolved markedly in both eyes. The authors characterise the recovery as partial and reversible: vision improved substantially but the case is not described as a full return to baseline.

How this fits the broader literature

This case is not the first to link semaglutide with NAION. A 2024 retrospective study at Massachusetts Eye and Ear identified hazard ratios of 4.28 in patients with type 2 diabetes and 7.64 in patients with overweight or obesity when comparing semaglutide users to non-GLP-1 receptor agonist users. A 2026 systematic review and meta-analysis of 12 large cohort studies (14.25 million participants) found pooled hazard ratios of 3.36 at one year and 2.37 at two and three years for NAION in semaglutide users with type 2 diabetes^[2]. The current BMC Ophthalmology case adds a detail that distinguishes it: bilateral simultaneous involvement and a concurrent branch retinal artery occlusion, which is a rarer and more severe presentation.

At the same time, a 2026 meta-analysis of 28 observational studies examining GLP-1 receptor agonists as a class against other antidiabetic medications found no statistically significant increase in NAION risk (RR 1.01; 95% CI 0.62 to 1.64)^[3]. The divergence between that finding and the semaglutide-specific analyses is not fully resolved. The class-level analysis includes drugs other than semaglutide and comparators that differ across studies, which may explain some of the discrepancy.

A 2026 scoping review of 13 randomised controlled trials (34,812 participants) similarly found that retinal vascular events, including optic ischaemic neuropathy, ran numerically higher in semaglutide arms (6 events in 11,757 semaglutide patients vs 1 in 11,105 placebo patients) but that the absolute incidence was low^[4]. The authors concluded that the pattern warranted further investigation through registry studies.

Risk factors already present

Before concluding that semaglutide caused this patient's optic events, it is worth setting out his baseline vascular risk. Obesity is an independent risk factor for NAION. A small optic disc anatomy (sometimes called a "disc at risk") increases susceptibility to anterior ischaemic injury. Conditions such as hypertension, obstructive sleep apnoea, and diabetes are also established risk factors, though the case report does not note these in this patient beyond obesity. The authors could not rule out that semaglutide-driven blood pressure changes contributed to the vascular event, or that the rapid weight-loss trajectory altered haemodynamics in a way that compromised optic nerve perfusion^[1].

What this is not

One case report cannot establish causation. The temporal association (11 months of use before onset, improvement after stopping) is suggestive, but NAION can resolve partially on its own regardless of drug use. The authors acknowledge this and describe the temporal association as the basis for their suspicion, not proof. No rechallenge was conducted, and no formal causality assessment was performed.

The proposed mechanism is vascular: semaglutide may alter optic nerve perfusion through effects on blood pressure and vascular autoregulation. Rapid weight loss can also cause transient haemodynamic changes. Both are plausible contributors but neither is proven in this patient or in the broader literature. The authors of the BMC Ophthalmology paper recommend baseline optic nerve assessment before initiating semaglutide^[1], but that recommendation reflects their interpretation of a single case, not a guideline or regulatory requirement.

Where this lands on the site

The semaglutide peptide page documents the known adverse-event profile from the SUSTAIN and STEP trial programmes, including the existing signal for worsening diabetic retinopathy in rapid HbA1c lowering. That signal involves a different mechanism (rapid HbA1c correction in established retinopathy) from the vascular pathway proposed for NAION. This case sits outside the established retinopathy mechanism and adds to a growing body of observational reports that regulators are watching.

Neither the EMA nor the FDA has issued a labelling change specific to NAION risk as of the editorial date of this article. The existing semaglutide prescribing information does not list NAION as a named adverse event. That regulatory status may change if the emerging literature produces a signal strong enough to warrant a label update. Any person using semaglutide who notices new or sudden changes in vision should contact their prescriber promptly. This article is for educational purposes and does not replace advice from a qualified healthcare professional.