Millions of Americans have been told at an eye exam that their intraocular pressure is high, that this is a risk factor for glaucoma, and that the plan is to keep an eye on it. Watchful waiting is the standard, and it is unsatisfying, because there is nothing in it for the patient to actually do.
A study published this month in JAMA Ophthalmology examined whether a common form of vitamin B3 changes that picture. Among 2,920 people with ocular hypertension who had not developed glaucoma, those with a record of taking nicotinamide were diagnosed with primary open-angle glaucoma at a rate of 3.5 percent over a mean 3.7 years, compared with 9.0 percent among matched people who were not. That works out to a 66 percent lower relative risk and a 5.5 percentage point absolute difference.
Before anyone reaches for a bottle, two things need saying. This describes an association in medical records, not a proven effect. And the population it describes is narrow.
Who This Actually Applies To
Ocular hypertension and glaucoma are not the same diagnosis, and the difference determines whether this study has anything to do with you.
Ocular hypertension means the pressure inside the eye is higher than normal, but the optic nerve looks healthy and the visual field is intact. It is a risk factor, not a disease. Estimates place the number of Americans in this category at roughly 3 to 6 million.
Primary open-angle glaucoma means the optic nerve has sustained damage, usually detected as thinning of the nerve fiber layer or as loss in the peripheral visual field. That damage is permanent. Glaucoma affects an estimated 95 million people worldwide and is a leading cause of irreversible blindness.
This study looked only at the first group, and asked whether nicotinamide delayed or prevented the transition to the second. If you already carry a glaucoma diagnosis, this particular finding was not about you. If you have never been told your eye pressure is elevated, it was not about you either.
Most people with ocular hypertension never develop glaucoma. That is worth holding onto, and it is also why a preventive option in this group is attractive: the intervention would be applied to many people, most of whom were never going to progress.
What the Researchers Did and Found
The team analyzed deidentified electronic medical records from a federated research network covering 67 U.S. health care organizations, spanning March 2006 to March 2026.
They identified 1,460 patients with ocular hypertension and at least one recorded instance of nicotinamide use, with a mean age of 54.4 years and 57.9 percent women. Each was matched one-to-one by propensity score against a control with no recorded history of nicotinamide or niacin use, mean age 54.9 years and 59.5 percent women.
Beyond the difference in glaucoma diagnoses, the nicotinamide group also saw a 43 percent lower rate of being prescribed topical pressure-lowering therapy and fewer laser procedures.
The researchers ran a sensitivity analysis restricted to patients whose first nicotinamide record came after the ocular hypertension diagnosis, which reduces the chance that the supplement use was somehow a marker of something that preceded it. Among those 947 matched pairs, followed a mean of 4.2 years, the association held with a hazard ratio of 0.42.
The authors framed their own conclusion cautiously, writing that nicotinamide represents "a potential adjunctive strategy complementary to standard therapy" that warrants further prospective investigation. JAMA Ophthalmology published an accompanying editorial by Simon K. Law examining what can and cannot be concluded from large commercially available datasets of this kind.
Why This Is Not Proof
The design is the limitation, and it is a substantial one.
This is a retrospective observational study. It can show that two things occurred together. It cannot show that one caused the other, and propensity score matching balances the variables researchers thought to include, not the ones nobody recorded.
Healthy-user bias is the specific worry here. People who take supplements tend to differ from people who do not in ways that medical records capture poorly. They often see doctors more regularly, follow instructions more consistently, and have more resources. Some of those same traits also affect whether and when a glaucoma diagnosis gets made.
The exposure measure is coarse. A record of nicotinamide use does not tell you the dose, how long it was taken, or whether the person actually took it. Nicotinamide is sold over the counter, so people taking it without a record would be misclassified as controls.
And detection matters in a disease diagnosed by examination. Glaucoma is found when someone looks for it. Differences in follow-up frequency between the groups could influence how quickly a diagnosis appears.
None of this means the finding is wrong. Nicotinamide has a plausible mechanism, supporting the NAD-dependent metabolism of the retinal ganglion cells that glaucoma destroys, and earlier work has examined it in people who already have the disease. It means the finding is a strong reason to run the trial, not a substitute for having run it.
The Dose Question Nobody Should Skip
The doses studied in glaucoma research are not the doses in a typical multivitamin.
The Glaucoma Nicotinamide Trial, a randomized, placebo-controlled, double-masked phase 3 study that has been enrolling since May 2022, randomizes patients with established glaucoma to 3 grams of nicotinamide daily following a six-week run-in at 1.5 grams, against matching placebo, with visual field progression measured over two years. It comprises the Swedish Glaucoma Nicotinamide Trial and the Vitamin B3 in Glaucoma Study, and is projected to complete in December 2026.
Three grams a day is a pharmacologic dose, far above the roughly 14 to 16 milligrams of niacin equivalents an adult needs from diet. Sustained high-dose nicotinamide has been associated with liver injury, and the American Glaucoma Society has cautioned about that risk at trial-level doses. Liver enzyme monitoring is part of how these doses are handled in a study setting.
Nicotinamide is also not interchangeable with niacin, another form of B3, which causes flushing and has its own liver considerations at high doses. Supplement labels are not always clear about which is inside.
Anyone taking a medication metabolized by the liver, anyone with existing liver disease, and anyone pregnant should treat this as a conversation with a clinician rather than a purchase decision.
What to Do With This
If you have ocular hypertension, the useful action is not buying a supplement. It is keeping your monitoring appointments, because the entire value of that diagnosis is catching optic nerve change early, and because intraocular pressure reduction remains the only intervention with proven benefit.
It is reasonable to bring this study to your ophthalmologist or optometrist and ask what they make of it, whether anything in your history would make high-dose nicotinamide inadvisable, and when the trial results are expected. That is a different conversation from starting something on your own.
Nobody should stop or reduce prescribed pressure-lowering eye drops based on this research. The study examined nicotinamide alongside standard care, not instead of it.
What Happens Next
The randomized trial is the event that matters, and it is projected to finish before the end of this year. Because it enrolls people who already have glaucoma rather than ocular hypertension, it will answer a related but not identical question, and a prevention trial in the ocular hypertension population would still be needed to test what this study observed.
The confirmed finding is an association between recorded nicotinamide use and lower rates of glaucoma diagnosis among people with elevated eye pressure. The people it concerns are the several million Americans in that specific category. The most reasonable action is keeping monitoring appointments and raising the question at the next one. The central uncertainty is whether the association survives a randomized test.
Frequently Asked Questions
What did the study find? Among 2,920 people with ocular hypertension, those with recorded nicotinamide use were diagnosed with primary open-angle glaucoma at 3.5 percent over a mean 3.7 years versus 9.0 percent in matched controls, a 66 percent lower relative risk.
Who does this apply to? People with ocular hypertension, meaning elevated eye pressure without optic nerve damage. It does not address people already diagnosed with glaucoma or people with normal eye pressure.
Does this prove vitamin B3 prevents glaucoma? No. It is a retrospective observational study using medical records. It shows an association and cannot establish cause.
Should I start taking nicotinamide? Not on the basis of this study. Talk with your eye doctor. Trial doses are far higher than typical supplements and carry liver risks.
How much is used in research? The ongoing randomized trial uses 3 grams daily after a run-in at 1.5 grams, which is a pharmacologic dose requiring monitoring, not a dietary amount.
Is nicotinamide the same as niacin? No. Both are forms of vitamin B3 with different effects and different safety considerations at high doses.
When will we know more? The Glaucoma Nicotinamide Trial is projected to complete in December 2026, though it enrolls people who already have glaucoma rather than ocular hypertension.
