The expanding use of GLP-1 receptor agonists like semaglutide has introduced an ophthalmologic safety question that practitioners may not yet be adequately screening for. A case reported in Survey of Ophthalmology documents a rare but clinically alarming presentation that warrants attention from anyone managing patients on this widely prescribed drug class.
A 38-year-old man with poorly controlled type 2 diabetes and hypertension — already on semaglutide — presented with sudden, painless vision loss in one eye. Examination revealed optic disc edema in the affected eye alongside optic disc pallor in the opposite eye, a combination classically associated with Foster Kennedy syndrome, which typically signals an intracranial mass. Full neuroimaging and systemic workup returned negative. The final diagnosis was pseudo-Foster Kennedy syndrome: a prior, unrecognized non-arteritic anterior ischemic optic neuropathy (NAION) in the pallored eye, and a new acute NAION event in the presenting eye. Both events were attributed in context to semaglutide use superimposed on an already high-risk vascular substrate.
NAION — ischemic injury to the optic nerve without arteritic inflammation — has historically been associated with cardiovascular risk factors, obstructive sleep apnea, and certain medications including phosphodiesterase inhibitors. Semaglutide's potential role has surfaced more recently, with a 2024 pharmacovigilance study raising flags about elevated NAION reporting rates in GLP-1 users with diabetes and obesity. The causal mechanism remains speculative but may involve rapid glycemic fluctuation affecting optic nerve perfusion, direct vascular effects, or changes in intraocular pressure dynamics. This case is significant precisely because it demonstrates bilateral sequential NAION — a devastating outcome — in a relatively young patient. The chief limitation is that it is a single case report; confounding from uncontrolled diabetes and hypertension cannot be excluded. Still, clinicians prescribing semaglutide, particularly to patients with pre-existing vascular risk, should consider baseline ophthalmic evaluation as a precautionary measure.