NAD+ and Glaucoma: What Emerging Research Means for Your Eyes

If you or someone you love has been diagnosed with glaucoma, you know the standard conversation: eye drops, intraocular pressure, and regular visual field tests. Those are critical. But they are also incomplete.

A growing body of scientific research is revealing something that many glaucoma patients sense instinctively: lowering eye pressure is not always enough. Some patients lose vision even when their pressure is well-controlled. Others with elevated pressure never develop glaucoma at all. Something else is going on inside the cells of the optic nerve, and researchers are increasingly pointing to one molecule as a key player: NAD+.

This article breaks down what NAD+ is, why it matters for glaucoma, what the latest clinical research shows, and what you can do about it. We will stick to what the science actually supports and be transparent about what is still being studied.

What Is NAD+ and Why Do Your Eyes Need It?

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme present in every cell of your body. It is essential for two things your retinal cells cannot survive without: energy production and cellular repair.

Inside your mitochondria, NAD+ acts as an electron carrier in the process that generates ATP, the energy currency your cells run on. Without adequate NAD+, mitochondria produce less ATP and generate more harmful byproducts called reactive oxygen species (ROS). NAD+ also activates a family of enzymes called sirtuins, which regulate DNA repair, inflammation, and cell survival.

Here is the problem: NAD+ levels decline with age. Animal studies have documented significant reductions across multiple tissues over the lifespan, and emerging human data confirms the trend, though exact percentages vary by tissue and measurement method. Your retina, being one of the most metabolically active tissues in your body, is likely to feel this decline acutely.

The NAD+ Depletion Theory of Glaucoma

Glaucoma damages retinal ganglion cells (RGCs), the neurons that carry visual information from your retina through the optic nerve to your brain. These cells have exceptionally long axons and high energy demands. They are among the most vulnerable cells in the central nervous system when mitochondrial function declines.

In 2017, a landmark study published in Science by Williams et al. demonstrated that age-related NAD+ depletion rendered retinal ganglion cells vulnerable to neurodegeneration in a mouse model of glaucoma. The researchers found that as NAD+ dropped, mitochondrial function deteriorated, and RGCs became susceptible to damage even at relatively modest levels of intraocular pressure.

Critically, when the researchers restored NAD+ levels using nicotinamide (a form of vitamin B3), the retinal ganglion cells were protected. The study showed robust neuroprotection even without lowering eye pressure. This suggested that NAD+ depletion is not merely correlated with glaucoma but may be a causal factor in determining whether RGCs survive or die under stress.

This research was published in one of the most rigorous scientific journals in the world and has since been cited hundreds of times. It fundamentally changed the conversation about glaucoma from "pressure management only" to "pressure management plus neuroprotection."

Nicotinamide Riboside: A More Efficient Path to NAD+

There are several precursors your body can use to make NAD+. Nicotinamide (also called niacinamide) is one. Nicotinic acid (niacin) is another. But nicotinamide riboside (NR) has attracted particular attention because of how efficiently it enters the NAD+ biosynthesis pathway.

NR is converted to NAD+ through the nicotinamide riboside kinase (NRK) pathway. Unlike nicotinamide, which can inhibit sirtuins at high doses, NR appears to boost NAD+ without this negative feedback loop. This makes it an attractive candidate for sustained NAD+ elevation.

A series of studies published in 2024 have strengthened the case for NR in eye health specifically:

Retinal ganglion cell protection. Zhang et al. (2024) published in Experimental Eye Research showing that NR protected cultured retinal ganglion cells from glutamate excitotoxicity, one of the primary mechanisms of RGC death in glaucoma. The protection was mediated through the SIRT1/PGC1-alpha pathway, which enhances mitochondrial biogenesis and suppresses apoptosis.

Glucocorticoid-induced glaucoma model. A separate 2024 study in Investigative Ophthalmology & Visual Science found that NR prevented extracellular matrix deposition in the trabecular meshwork, partially prevented intraocular pressure elevation, and protected retinal ganglion cells in a steroid-induced glaucoma model. The mechanism involved preserving mitochondrial integrity and reducing oxidative damage.

DBA/2J mouse model. Another 2024 study showed that oral NR supplementation at high doses increased retinal NAD+ levels by over 270% and robustly protected RGCs and optic nerve axons in the DBA/2J mouse, one of the most widely used animal models of chronic glaucoma.

The Clinical Trial: Testing NR in Human Glaucoma Patients

The preclinical evidence for NR in glaucoma is now substantial enough that researchers have moved to human clinical trials. A randomized, double-blind, placebo-controlled trial led by Leung et al. (protocol published 2022 in Trials) is testing 300 mg of nicotinamide riboside daily in 125 patients with primary open-angle or normal-tension glaucoma over 24 months.

The primary outcome is change in retinal nerve fiber layer (RNFL) thickness, measured by optical coherence tomography. Secondary outcomes include visual field sensitivity and pattern electroretinography (PERG), which measures retinal ganglion cell function directly.

This trial is significant for several reasons. First, the 300 mg dose being tested is a standard, commercially available supplementation dose, not a pharmaceutical mega-dose. Second, the 24-month duration is long enough to detect meaningful changes in glaucoma progression, which is notoriously slow. Third, the study design (randomized, double-blind, placebo-controlled) is the gold standard for clinical evidence.

What we know so far: The trial results have not yet been fully published. We cannot claim that NR is a proven treatment for glaucoma based on this trial. But the fact that a rigorously designed clinical trial is testing this specific molecule at this specific dose tells us that the scientific community considers the preclinical evidence compelling enough to warrant human testing.

What About Nicotinamide vs. Nicotinamide Riboside?

You may have seen headlines about "vitamin B3 for glaucoma" referencing nicotinamide (niacinamide), not nicotinamide riboside. Both are NAD+ precursors, and both have research supporting their potential in glaucoma. The Glaucoma Foundation and several research groups have highlighted nicotinamide supplementation based on the Williams et al. (2020) Science paper.

So what is the difference? Nicotinamide is cheaper and more widely available, but at the high doses sometimes discussed (1,000-3,000 mg), it can inhibit sirtuin activity, potentially counteracting some of the benefits of NAD+ elevation. NR avoids this issue because it enters the NAD+ pathway through a different route (the NRK pathway) that does not trigger sirtuin inhibition.

Both approaches have merit, and the research is still sorting out which form is optimal. But for individuals seeking a targeted NAD+ strategy without the dose-dependent concerns of high-dose nicotinamide, NR represents a well-studied alternative.

The Bigger Picture: Why NAD+ Is Only Part of the Equation

NAD+ is not a cure for glaucoma, and anyone who tells you otherwise is not reading the research carefully. Glaucoma is a complex, multifactorial disease. Intraocular pressure management remains the cornerstone of treatment. Regular monitoring of visual fields and optic nerve health is essential.

What the NAD+ research offers is a complementary strategy that addresses a different aspect of the disease: the cellular vulnerability of retinal ganglion cells. Think of it this way. Lowering eye pressure reduces the external stress on RGCs. Supporting NAD+ levels strengthens the internal resilience of those same cells. Both matter.

Other ingredients can further support this approach. CoQ10 is a critical cofactor in the mitochondrial electron transport chain and has shown neuroprotective effects in retinal models. Ginkgo biloba has clinical evidence for improving ocular blood flow, which helps ensure retinal cells receive adequate oxygen and nutrients. Lutein, while primarily studied for macular degeneration, provides broad antioxidant protection throughout the retina.

Practical Takeaways

Do not stop your glaucoma medications. Nothing in this article replaces prescribed treatment. IOP management is essential and proven. For lifestyle-based approaches, see our guide to natural ways to support healthy eye pressure.

Talk to your ophthalmologist about NAD+ research. Many eye care professionals are aware of the Williams et al. findings and the ongoing clinical trials. Bring this article to your next appointment as a conversation starter.

If you are looking to incorporate an NAD+ precursor into your daily routine, look for a supplement that uses a specific, disclosed dose of NR rather than a proprietary blend. The clinical research on NR in eye health has used doses generally in the 300 mg range, which gives you a reference point for comparison.  Sight Guard by NADefense contains NR alongside CoQ10, ginkgo biloba extract, lutein, and calcium pyruvate, a formula designed to support cellular energy and antioxidant balance in aging eyes as part of a daily wellness routine. It is designed to complement your prescribed care, not replace it.*

Be patient and realistic. Neuroprotective effects are measured over months and years, not days. The clinical trial is 24 months long for a reason. If you start supplementing, commit to consistent daily use and track your outcomes with your eye care provider.

Stay informed. This is an active area of research. Clinical trial results are expected in the coming years. We will update this article as new findings are published.

The Bottom Line

The connection between NAD+ depletion and glaucoma is supported by robust preclinical research and is now being tested in a rigorous human clinical trial. While we cannot yet call NR a proven glaucoma treatment, the mechanistic evidence is compelling: NAD+ supports the mitochondrial energy production that retinal ganglion cells depend on for survival, and replenishing NAD+ in animal models consistently protects these cells from degeneration.

For the millions of people living with or at risk for glaucoma, this represents a genuinely new avenue, one that complements existing treatments rather than replacing them. The question is no longer whether NAD+ matters for retinal health. The evidence shows it does. The remaining question is how much benefit human patients will see, and the clinical trials underway will answer that.

References

1. Williams PA, Harder JM, Foxworth NE, et al. (2017). "Vitamin B3 modulates mitochondrial vulnerability and prevents glaucoma in aged mice." Science. DOI: 10.1126/science.aal0092

2. Zhang et al. (2024). "The role of nicotinamide riboside in the preservation of retinal ganglion cells using an in vitro glutamate-induced excitotoxicity model." Experimental Eye Research. DOI: 10.1016/j.exer.2024.110126

3. Zhang et al. (2024). "Protective Effect of Nicotinamide Riboside on Glucocorticoid-Induced Glaucoma." Investigative Ophthalmology & Visual Science. DOI: 10.1167/iovs.65.8.1

4. Zhang et al. (2024). "Oral supplementation with Nicotinamide Riboside treatment protects RGCs in DBA/2J mouse model." bioRxiv preprint. DOI: 10.1101/2024.12.03.626460

5. Leung et al. (2022). "Nicotinamide riboside as a neuroprotective therapy for glaucoma: study protocol for a randomized, double-blind, placebo-controlled trial." Trials. DOI: 10.1186/s13063-021-05968-1

6. Silva et al. (2023). "The use of Nicotinamide and Nicotinamide riboside as an adjunct therapy." European Journal of Ophthalmology. DOI: 10.1177/11206721231161101

7. Zhang et al. (2021). "Systemic Treatment with Nicotinamide Riboside Is Protective in Two Mouse Models." Pharmaceutics. DOI: 10.3390/pharmaceutics13060893