A newly formed multidistrict litigation (MDL 3163) is consolidating federal lawsuits alleging that GLP-1 receptor agonist drugs — including Novo Nordisk's Ozempic and Wegovy — cause non-arteritic anterior ischemic optic neuropathy (NAION), a condition that can result in sudden and permanent vision loss.
The Scientific Basis
The litigation was spurred by a July 2024 study published in JAMA Ophthalmology by researchers at Massachusetts Eye and Ear, a Harvard Medical School affiliate. The study found that patients taking semaglutide-based drugs had a significantly elevated risk of developing NAION compared to patients taking other diabetes or weight-loss medications.
NAION occurs when blood flow to the optic nerve is disrupted, causing sudden, painless vision loss — typically in one eye initially, with risk of the second eye being affected later. The condition has no proven treatment, and vision loss is often permanent.
Current Status of the MDL
MDL 3163 was established by the Judicial Panel on Multidistrict Litigation (JPML) and assigned to a federal court for coordinated pretrial proceedings. Early case management conferences are underway, with initial discovery deadlines being established.
Plaintiffs allege that Novo Nordisk knew or should have known about the NAION risk based on clinical trial data and post-market adverse event reports, but failed to adequately warn patients and prescribing physicians. The company's current drug labels do not list NAION as a potential side effect.
The Broader GLP-1 Litigation Landscape
This MDL is separate from other GLP-1-related lawsuits involving claims of gastroparesis (stomach paralysis), pancreatitis, and bowel obstruction. Together, the various GLP-1 litigations represent one of the fastest-growing areas of pharmaceutical mass tort law, reflecting the enormous popularity of these drugs — over 40 million prescriptions were written for semaglutide products in 2025 alone.
What Affected Patients Should Know
Individuals who experienced sudden vision changes while taking Ozempic, Wegovy, or other semaglutide-based medications should consult an ophthalmologist and consider speaking with a mass tort attorney about their legal options.