A federal judge in Philadelphia is overseeing a rapidly expanding mass tort litigation that could affect millions of Americans who use popular GLP-1 weight loss and diabetes drugs. MDL 3163 — the standalone federal docket for Ozempic vision loss lawsuit claims — has grown from 21 cases at its December 2025 creation to 200 cases as of September 2026, with no signs of slowing. At the center of this litigation is a condition called non-arteritic anterior ischemic optic neuropathy (NAION), a sudden and often permanent form of vision loss that plaintiffs allege was caused by semaglutide and tirzepatide drugs — and that drug manufacturers knew, or should have known, carried this risk long before warning patients or their doctors.
What Is MDL 3163 and Why Was It Created Separately?
On December 15, 2025, the U.S. Judicial Panel on Multidistrict Litigation (JPML) formally created IN RE: Glucagon-like Peptide-1 Receptor Agonists (GLP-1 RAs) Non-Arteritic Anterior Ischemic Optic Neuropathy Products Liability Litigation, designated MDL 3163. The panel centralized all federal NAION-related GLP-1 lawsuits before Judge Karen Spencer Marston in the Eastern District of Pennsylvania — the same judge presiding over the parallel GI injury MDL 3094, which now carries more than 3,626 cases.
Critically, the JPML rejected Eli Lilly’s request to fold NAION claims into the existing gastrointestinal injury MDL. Instead, regulators created a standalone docket, recognizing that vision loss claims raise distinct scientific, medical, and legal questions from gastroparesis and bowel obstruction claims. This separation matters: it signals that the court views NAION as a serious, independently cognizable injury category deserving its own litigation track.
Defendants named in MDL 3163 include Novo Nordisk (makers of Ozempic, Wegovy, and Rybelsus, all semaglutide-based) and Eli Lilly (makers of Mounjaro and Zepbound, which contain tirzepatide, a dual GIP/GLP-1 receptor agonist). If you have used any of these medications and experienced sudden vision changes, your claim may fall within this docket. You can use our medical malpractice calculator to begin estimating the potential value of a defective drug injury claim.
Beyond the federal MDL, over 100 additional GLP-1 NAION cases have been filed in New Jersey state court, centralized in Bergen County under MCL No. 644, creating a parallel state-level litigation track that further underscores the breadth of this emerging mass tort.
The Science Behind the Ozempic Vision Loss Lawsuit
What Is NAION?
Non-arteritic anterior ischemic optic neuropathy — NAION — is sometimes described as an “eye stroke.” It occurs when blood flow to the optic nerve is suddenly interrupted, causing rapid, painless, and in most cases irreversible vision loss in one or both eyes. Unlike many medical conditions, NAION typically strikes without warning and offers no reliable treatment to restore lost sight. For patients who were using Ozempic or Wegovy for weight management or blood sugar control, the onset of this condition has been devastating and life-altering.
What the Research Shows
The causal science linking GLP-1 receptor agonists to NAION has developed rapidly. A landmark July 2024 study published in JAMA Ophthalmology by researchers at Harvard Medical School found that semaglutide users faced a dramatically elevated risk of NAION compared to patients using other diabetes or weight-loss medications. The study examined thousands of patient records and found that those taking semaglutide for type 2 diabetes were more than four times as likely to develop NAION, while those taking it for weight loss were more than seven times as likely. These findings sent shockwaves through both the medical community and the legal landscape, providing plaintiffs’ attorneys with powerful epidemiological evidence to support failure-to-warn claims.
More recently, in June 2025, the European Medicines Agency (EMA) conducted its own review and found that the risk of NAION with semaglutide was more than doubled compared to other diabetes medications — with an estimated occurrence of up to 1 in 10,000 patients. As a result, the EMA recommended updating the semaglutide label to list NAION as a “very rare” side effect, marking one of the first formal regulatory acknowledgments of this risk anywhere in the world. That regulatory action has since become a focal point of litigation in 2026, with plaintiffs arguing it reinforces what manufacturers should have disclosed to U.S. patients far sooner.
What the FDA Has — and Has Not — Done
As of September 2026, the U.S. Food and Drug Administration has not required Novo Nordisk or Eli Lilly to add a NAION warning to their U.S. drug labels. This regulatory gap is central to every Ozempic vision loss lawsuit currently pending in MDL 3163. Plaintiffs argue that the FDA’s silence does not mean the risk is absent — it means the manufacturers have not been compelled to act, and that in the meantime, patients continue to be prescribed these drugs without any knowledge of the potential for sudden, irreversible vision loss.
The FDA did issue a drug safety communication in 2024 acknowledging the Harvard study’s findings and stating it was evaluating the signal. However, no label change, black box warning, or Dear Healthcare Provider letter has followed. The contrast between the EMA’s June 2025 label update recommendation and the FDA’s continued inaction has become a significant talking point in the litigation, with plaintiffs’ experts expected to highlight the regulatory divergence as evidence that the U.S. warning standard has not been met.
Why This Matters for Failure-to-Warn Claims
Under U.S. products liability law, pharmaceutical manufacturers have a duty to warn prescribing physicians — and through them, patients — of known or reasonably knowable risks associated with their drugs. This duty does not require a government mandate. It requires only that the manufacturer knew or should have known of a risk and failed to adequately disclose it. Plaintiffs in MDL 3163 argue that by the time many of them were prescribed semaglutide or tirzepatide, sufficient scientific evidence existed to support a NAION warning — and that Novo Nordisk and Eli Lilly made a calculated decision not to update their labels, prioritizing market dominance over patient safety.
The EMA’s June 2025 recommendation strengthens this argument considerably. If European regulators found the evidence compelling enough to require a label update, plaintiffs’ attorneys will argue, U.S. manufacturers had no legitimate basis for withholding the same information from American patients and their doctors.
MDL 3163 Case Growth and Docket Timeline
The growth of MDL 3163 has been striking by any measure. When the JPML created the docket in December 2025, just 21 cases were transferred in. By September 2026, that number had climbed to 200 pending lawsuits — nearly a tenfold increase in less than a year. Pretrial fact discovery has a deadline set for October 2026, meaning the litigation is entering a critical phase in which both sides must exchange documents, produce witnesses for deposition, and build the evidentiary record that will shape any future trials or settlement negotiations.
As of September 2026, no global settlement has been announced, and no cases have gone to trial. This is consistent with the typical lifecycle of pharmaceutical mass torts, which often take several years to progress from MDL formation to bellwether trials and then to broader resolution. The GI injury MDL 3094, which was created earlier and involves a much larger case count, similarly has not yet produced a global settlement, suggesting that Novo Nordisk and Eli Lilly are prepared for extended litigation across both dockets.
The parallel New Jersey state court litigation under MCL No. 644 continues to develop alongside the federal MDL, and attorneys are watching both tracks closely for signs of which forum may produce the first meaningful rulings on general causation — a threshold question that will determine whether these cases can proceed to juries at all.
June 2, 2026 Science Day: A Pivotal Moment for the Litigation
One of the most consequential early developments in MDL 3163 was the Science Day held on June 2, 2026, before Judge Marston. Science Days are informal, non-evidentiary proceedings in which both sides present their scientific theories directly to the presiding judge. They are designed to help the court develop a working understanding of the medical and biological issues before formal expert discovery begins.
At the June 2026 Science Day, plaintiffs’ experts presented their theory that GLP-1 receptor agonists alter blood flow dynamics and vascular pressure in ways that make the optic nerve vulnerable to ischemic injury — essentially, that the mechanism by which these drugs work creates a physiological predisposition to NAION in susceptible patients. Defense experts pushed back, arguing that the studies to date are observational, that correlation does not equal causation, and that the baseline risk of NAION in the diabetic and obese populations who use these drugs complicates any causal inference.
The scientific debate is far from over. But Science Day served an important function: it put both the court and the defendants on notice that plaintiffs have a credible, expert-supported scientific theory — one that has only been reinforced by subsequent regulatory action in Europe and the growing body of peer-reviewed literature examining GLP-1 drugs and ocular risk.
The Regulatory Gap at the Heart of Every Ozempic Vision Loss Lawsuit
Perhaps the most powerful legal narrative running through MDL 3163 is the gap between what regulators in other jurisdictions have done and what the FDA has required of U.S. manufacturers. The EMA’s June 2025 finding — that semaglutide more than doubles the risk of NAION compared to other diabetes medications and that the condition should be listed as a very rare side effect — stands in sharp contrast to the continued absence of any NAION warning on U.S. drug labels as of September 2026.
For plaintiffs’ attorneys, this regulatory divergence is a gift. It allows them to argue that the science was sufficient to trigger a warning obligation, that at least one major regulatory body agreed, and that U.S. patients were left without that protection through no fault of their own. It also undercuts any defense argument that the risk was simply unknowable or scientifically unsettled — if European regulators found the evidence compelling, the manufacturers cannot credibly claim they lacked adequate basis to act.
The Medicare GLP-1 cost cap that took effect July 1, 2026 — which limits certain GLP-1 prescription costs to $50 per month for eligible beneficiaries — is also worth noting in this context. By making these drugs more accessible and affordable to a broader population of older Americans, the policy change is likely to expand the universe of potential plaintiffs and increase the long-term visibility of any adverse effects, including NAION, in the Medicare population. Attorneys monitoring the litigation expect new case filings to continue accelerating through the remainder of 2026 and into 2027.
What GLP-1 Patients Who Suffered Sudden Vision Loss Should Do Right Now
If you or someone you love experienced sudden, painless vision loss in one or both eyes while taking Ozempic, Wegovy, Rybelsus, Mounjaro, or Zepbound, you may have a viable claim in MDL 3163. Here is what you should do immediately:
Seek medical attention and obtain a formal diagnosis. NAION must be diagnosed by an ophthalmologist or neuro-ophthalmologist. A formal diagnosis in your medical records is essential to any legal claim. If you have not yet seen a specialist, do so as soon as possible.
Preserve your prescription records. Document which drug you were taking, the dosage, the prescribing physician, the pharmacy, and the dates of use. This information will be critical to establishing your exposure history in litigation.
Consult an experienced mass tort attorney promptly. Statutes of limitations vary by state, and some states impose discovery rules that start the clock from the date you knew or should have known about the connection between your drug use and your injury. Waiting can cost you your right to file. With pretrial fact discovery in MDL 3163 set to close in October 2026, now is the time to act.
Do not discontinue your medication without speaking to your doctor. Legal consultation and medical management are separate processes. Never stop a prescribed medication abruptly without your physician’s guidance, even if you are pursuing a lawsuit.
Frequently Asked Questions About the Ozempic Vision Loss Lawsuit
What drugs are covered by the GLP-1 NAION MDL 3163?
MDL 3163 covers NAION claims arising from the use of GLP-1 receptor agonist medications, including semaglutide-based drugs marketed under the brand names Ozempic, Wegovy, and Rybelsus (manufactured by Novo Nordisk), and tirzepatide-based drugs marketed as Mounjaro and Zepbound (manufactured by Eli Lilly). If you suffered NAION while using any of these medications, your claim may be eligible for inclusion in the MDL or the parallel New Jersey state court litigation.
Is MDL 3163 the same as the Ozempic GI injury lawsuit?
No. MDL 3163 is a separate, standalone docket specifically for NAION vision loss claims. The GI injury litigation — which involves claims of gastroparesis, stomach paralysis, bowel obstruction, and related conditions — is handled under MDL 3094, also before Judge Marston in Philadelphia. The JPML specifically rejected consolidating the two dockets, recognizing that vision loss and gastrointestinal injury claims involve different injuries, different science, and different legal theories. If you have both types of injuries, you may have claims in both MDLs, but they are handled separately.
Why hasn’t the FDA added a NAION warning to Ozempic or Wegovy labels?
As of September 2026, the FDA has not required a NAION warning on U.S. GLP-1 drug labels. The agency stated in 2024 that it was evaluating the safety signal, but no formal regulatory action has followed. This is not uncommon in pharmaceutical regulation — the FDA’s process for requiring label changes can be slow, particularly when manufacturers dispute the causation evidence. By contrast, the European Medicines Agency recommended a label update in June 2025 after concluding that semaglutide more than doubled the risk of NAION compared to other diabetes medications. Plaintiffs in MDL 3163 are expected to use this regulatory divergence as evidence that U.S. manufacturers had sufficient basis to warn patients and chose not to.
What does the Harvard study actually prove about Ozempic and vision loss?
The July 2024 Harvard study published in JAMA Ophthalmology was an observational, retrospective cohort study — meaning researchers analyzed existing patient records rather than conducting a controlled clinical trial. It found that semaglutide users had a significantly elevated rate of NAION diagnoses compared to patients taking other medications for the same underlying conditions. For type 2 diabetes patients, the risk was more than four times higher; for weight-loss patients, more than seven times higher. Observational studies cannot, by themselves, prove causation in a legal or scientific sense — but they are powerful evidence of association, and they are the same type of evidence used to establish the link between smoking and lung cancer decades ago. Combined with the EMA’s regulatory findings and plaintiffs’ expert testimony on biological mechanism, this body of research forms the scientific core of MDL 3163.
How long do I have to file an Ozempic vision loss lawsuit?
The deadline to file an Ozempic vision loss lawsuit depends on the statute of limitations in your state, which typically ranges from two to four years from the date of injury or the date you discovered — or reasonably should have discovered — the connection between your drug use and your vision loss. Some states apply a discovery rule that delays the start of the limitations period, which can be favorable for patients who were not immediately aware that their NAION was linked to GLP-1 drug use. Because these deadlines vary and can expire without warning, it is critical to consult with a mass tort attorney as soon as possible. Missing the filing deadline means permanently losing your right to compensation, regardless of how strong your underlying claim may be.
Victoria Chambers is a mass tort and class action research analyst with extensive knowledge of multi-district litigation (MDL), defective product cases, dangerous drug lawsuits, and toxic exposure claims across the United States. Victoria is not an attorney and the information provided is for educational purposes only.