At every comprehensive eye exam, before you read a single letter on the chart, someone measures the pressure inside your eyes. Most people have no idea why. Here is what that number means, why your doctor cares about it, and what the emerging research says about supporting the structures it affects.
What eye pressure is
Your eye maintains its shape the way a basketball does — with internal pressure. A clear fluid called aqueous humor is continuously produced inside the front of the eye, circulates, and drains away. The balance between production and drainage creates intraocular pressure (IOP), measured in millimeters of mercury (mmHg). For most adults, measured pressure falls roughly between 10 and 21 mmHg, though what is “right” varies from person to person — there is no single number that is healthy for everyone.
Why your doctor measures it
The optic nerve — the cable of more than a million fibers carrying everything you see to the brain — exits the back of the eye, and it is sensitive to pressure. Elevated IOP is the major modifiable risk factor for glaucoma, a group of conditions in which optic nerve fibers are gradually lost, typically starting with peripheral vision and typically without any symptoms you would notice. That combination — silent, gradual, irreversible — is why pressure checks and dilated exams are built into every routine visit. The National Eye Institute's glaucoma overview, linked below, is a clear introduction.
What affects it
Pressure fluctuates through the day and responds to many things: genetics and age, certain medications (notably steroids), eye anatomy, even body position. Regular aerobic exercise is associated with modest reductions. What a pressure reading is not is a grade you can feel — high pressure has no sensation, which is why measurement matters.
Where nutrition research is heading
The most closely watched nutrient in this area is nicotinamide, a form of vitamin B3 that supports cellular energy metabolism in retinal cells. In a placebo-controlled crossover trial published in 2020, glaucoma patients taking high-dose nicotinamide alongside their usual care showed measurable improvement in inner retinal function on electrophysiology testing. This research is early — it concerns visual function measures rather than long-term outcomes, used doses only under medical supervision, and does not make nicotinamide a treatment for any disease. But it is a genuinely interesting frontier, and it is why B3 appears in modern eye-health formulations, including the research we track on our Science page.
What to do with all this
- Know your numbers. Ask what your pressure is at each exam, the way you would ask about blood pressure.
- Keep the schedule your doctor sets. Pressure-related conditions are managed best when caught early — and they are usually caught at routine exams, not because of symptoms.
- Tell your doctor your family history. Glaucoma runs in families, and family history changes how closely you should be watched.
- Discuss supplements before starting them. Especially with an eye condition, your ophthalmologist should know everything you take.
— The Pristene Medical Team
Selected research
Independent, public sources for the science discussed above.
- National Eye Institute. Glaucoma: overview, eye pressure, and the optic nerve. Read at nei.nih.gov
- Hui F, Tang J, Williams PA, et al. Improvement in inner retinal function in glaucoma with nicotinamide (vitamin B3) supplementation: a crossover randomized clinical trial. Clinical & Experimental Ophthalmology. 2020;48(7):903–914. Read on PubMed
Important
This page is general educational information and is not medical advice. It is not a diagnosis and does not replace an examination by your own eye care professional.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
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