An eye pressure reading of 23 mmHg sits just above the range most eye doctors consider statistically normal, which tops out around 21 mmHg. In a large population study, the average intraocular pressure (IOP) was about 14.5 mmHg, and the 97.5th percentile across age groups landed between 19 and 21 mmHg.1PubMed Central. Intraocular pressure and its normal range adjusted for ocular and systemic parameters: The Beijing Eye Study 2011 That said, a reading of 23 does not mean you have glaucoma, and it does not mean you definitely need treatment. What it does mean is that your eye doctor will want to look more closely at several other factors before deciding what comes next.
What Is Happening Inside Your Eye at 23 mmHg
Your eye constantly produces a clear fluid called aqueous humor, which nourishes the front structures of the eye and then drains out through a tiny mesh-like tissue near the base of your iris. The balance between how fast this fluid is made and how quickly it leaves determines your eye pressure. About three-quarters of the drainage resistance sits in that meshwork tissue.2PubMed Central. Aqueous humor dynamics: a review When the outflow slows down even slightly, pressure creeps up. At 23, the system is not drastically out of balance, but the fluid is backing up a little more than average.
The concern with sustained higher pressure is its effect on the optic nerve at the back of the eye. The optic nerve is made up of over a million nerve fibers that carry visual information to your brain. Elevated pressure can gradually compress and damage those fibers, leading to blind spots you may not notice until significant harm has already occurred. That slow, painless progression is what makes glaucoma so tricky to catch on your own.
How Your Eye Pressure Was Measured Matters
Not every eye pressure measurement is created equal, and the device used to take your reading can shift the number by a few points in either direction. The gold-standard instrument is Goldmann applanation tonometry, which gently flattens a tiny area of your cornea after numbing drops are applied. Many offices, though, use a non-contact air-puff tonometer because it is faster and does not require numbing drops. Studies consistently show that the air-puff method tends to read higher than Goldmann, often by about 1 to 3 mmHg on average.3PubMed Central. Comparative evaluation of intraocular pressure with an air-puff tonometer versus a Goldmann applanation tonometer That gap tends to widen at higher pressures. One study comparing the two methods in normal eyes found the air-puff tonometer consistently produced higher readings, especially in people whose pressures were already at 20 mmHg or above.4PubMed Central. A Comparative Study Between the Goldmann Applanation Tonometer and the Non-Contact Air-Puff Tonometer (Huvitz HNT 7000) in Normal Eyes
Handheld devices like the Tono-Pen also tend to run a few points higher than Goldmann, with similar patterns in both healthy eyes and those with glaucoma.5PubMed Central. Comparison of Goldmann Applanation, Noncontact Air Puff, and Tono-Pen XL Tonometry in Normal Controls versus Glaucoma Patients at a University Hospital in Riyadh, Saudi Arabia So if your 23 came from an air-puff test at a screening or a routine visit, the “true” Goldmann-equivalent pressure could be closer to 20 or 21. That does not make the reading meaningless, but it is worth asking your eye doctor which device was used and whether a confirmatory measurement with Goldmann tonometry would be helpful.
Corneal Thickness Changes the Math
Your cornea’s thickness also influences the reading. Thicker corneas resist being flattened, which makes the tonometer record a higher pressure than what is actually inside the eye. Thinner corneas do the opposite, underestimating the true pressure. Research has confirmed a meaningful correlation between corneal thickness differences between eyes and the IOP gap measured between those same eyes.6PubMed. Effect of central corneal thickness on dynamic contour tonometry and Goldmann applanation tonometry in primary open-angle glaucoma A pachymetry test, which takes seconds and is painless, measures your corneal thickness and helps your doctor interpret whether 23 truly means 23 or is an artifact of corneal anatomy. This measurement is particularly important because thin corneas are also an independent risk factor for developing glaucoma, separate from their effect on the pressure reading itself.
Why a Single Reading Does Not Tell the Whole Story
Eye pressure is not a fixed number. It fluctuates throughout the day and night in a rhythmic pattern. In healthy people, pressure tends to be lower during the afternoon and higher during the nighttime hours while you sleep.7PubMed. 24-h monitoring devices and nyctohemeral rhythms of intraocular pressure The single snapshot your doctor takes during a daytime visit might catch a peak, a trough, or something in between. A reading of 23 at 2 p.m. might represent your pressure’s highest point of the day, or it might be your baseline before it climbs further while you sleep.
Standard office tonometry simply cannot capture the nocturnal spike that many people experience. Researchers have been working on wearable contact-lens sensors that could track pressure around the clock, including during sleep, to give a far more complete picture.8PubMed. Soft wearable contact lens sensor for continuous intraocular pressure monitoring Until such devices become routine, doctors rely on multiple office visits at different times of day to get a sense of your pressure’s range. If your first reading is 23, expect to be asked back for at least one or two follow-up measurements before any treatment decisions are made.
Short-term spikes also occur with common activities. During weightlifting, the average pressure in one study jumped to about 39 mmHg, an increase of roughly 27 mmHg above resting levels.9PubMed Central. Intraocular pressure fluctuation during resistance exercise Even holding your breath and bearing down, something you might do while straining on the toilet or blowing up a balloon, raised pressure by a couple of points in the majority of people tested.10PubMed. Intraocular pressure and ocular pulse amplitude variations during the Valsalva maneuver These transient spikes come back down quickly and are not the same as chronically elevated pressure, but they illustrate how dynamic the system is.
The Risk Factors That Actually Determine What 23 Means for You
The Ocular Hypertension Treatment Study, one of the most influential trials in this area, followed thousands of people with elevated eye pressures to see who eventually developed glaucoma and who did not. The factors that predicted progression included older age, higher IOP, thinner corneas, a larger cup-to-disc ratio (an anatomical feature your doctor can see when examining the optic nerve), and certain visual field findings.11PubMed. The Ocular Hypertension Treatment Study: baseline factors that predict the onset of primary open-angle glaucoma A follow-up validation study confirmed these same risk factors as reliable predictors.12JAMA Ophthalmology. Validation of a Predictive Model to Estimate the Risk of Conversion From Ocular Hypertension to Glaucoma
Here is the practical takeaway: a 35-year-old with thick corneas, a healthy-looking optic nerve, and a pressure of 23 faces a very different situation than a 68-year-old with thin corneas and an optic nerve that already looks a bit cupped. The number alone is almost never enough to make a treatment decision. Your doctor will weigh all of these factors together, sometimes plugging them into a risk calculator, to estimate your personal likelihood of developing glaucoma over the next five to ten years.
Ethnicity, Age, and Systemic Health
Background risk varies with ethnicity. Data from a large Canadian aging study found that Black individuals had mean IOP levels roughly 1.5 mmHg higher than white individuals after adjusting for other variables, and their odds of reporting glaucoma were about two and a half times greater.13PubMed Central. Exploring ethnic and racial differences in intraocular pressure and glaucoma: The Canadian Longitudinal Study on aging East Asian and Southeast Asian populations, by contrast, tended to have somewhat lower IOP on average. These differences mean that a pressure of 23 carries different weight depending on your demographic risk profile.
Systemic health conditions also play a role. The Barbados Eye Studies found that hypertension and higher blood pressure were associated with elevated IOP, and that the incidence of high eye pressure increased substantially with age, with rates roughly two and a half times higher in people aged 70 and older compared to those in their 40s.14PubMed. Factors related to the 4-year risk of high intraocular pressure: the Barbados Eye Studies If you have uncontrolled high blood pressure, managing it may indirectly help your eye pressure too, though the connection is complex and lowering blood pressure is not a replacement for glaucoma treatment when it is needed.
Could Something Specific Be Pushing Your Pressure Up?
Steroid medications are one of the most common culprits behind unexpectedly elevated IOP. The link between steroids and raised eye pressure has been documented since the 1950s, and it applies to steroids in any form: eye drops, nasal sprays, inhalers, skin creams, oral pills, and injected formulations.15PubMed Central. Steroid-induced Glaucoma: An Avoidable Irreversible Blindness If you are using a steroid for asthma, allergies, arthritis, or any other condition, that could be the entire explanation for a 23. Some people are genetically more susceptible to steroid-induced pressure rises than others. Researchers have found that certain anatomical features in the eye’s drainage tissue, measured by imaging, can help predict who is at higher risk of this reaction.16PubMed Central. Association of trabecular meshwork height with steroid-induced ocular hypertension
If steroids are driving your elevated reading, the pressure often comes back down once the medication is reduced or stopped. Tell your eye doctor about every medication you use, including over-the-counter nasal sprays and topical skin creams, because patients frequently forget to mention these, and doctors do not always ask.
When Low Pressure Still Causes Damage
One of the most counterintuitive facts about glaucoma is that it can develop in people whose eye pressure never exceeds the normal range. This condition, called normal-tension glaucoma, involves the same kind of optic nerve damage and visual field loss seen in the high-pressure version, but without clearly abnormal IOP readings.17PubMed Central. Normal-tension glaucoma (Low-tension glaucoma) This is part of the reason eye doctors insist that pressure is only one piece of the puzzle. The health of your optic nerve and your visual field are at least as important as the number on the tonometer.
Normal-tension glaucoma makes the case that whatever “safe” pressure means, it is different for every individual. Some optic nerves can tolerate pressures in the mid-20s without harm for decades. Others sustain damage at 16. Your doctor’s job is to find your personal threshold and keep you below it.
What Happens If Treatment Is Needed
If your doctor determines that your 23 warrants action, the first step is usually prescription eye drops. Several drug classes work by either reducing how much fluid the eye makes or by improving how quickly it drains. Drops are effective for most people, but they come with a practical challenge: sticking with them long-term. One cross-sectional study found that nearly 60% of glaucoma patients reported low adherence to their drop regimen.18PubMed Central. Impact of Sociodemographic and Psychological Factors on Adherence to Glaucoma Treatment – A Cross-Sectional Study Side effects like eye redness, stinging, and cost all contribute, as does the fact that elevated pressure causes no symptoms you can feel, which makes it easy to skip doses without immediate consequences.
Laser Treatment
Selective laser trabeculoplasty (SLT) has become an increasingly popular option, especially for people who struggle with daily drops. The procedure takes a few minutes, uses targeted laser energy on the drainage tissue to improve outflow, and is effective as a first-line treatment.19PubMed Central. Selective Laser Trabeculoplasty in the Treatment of Ocular Hypertension and Open-Angle Glaucoma: Clinical Review In one study of patients starting with a mean IOP of about 27 mmHg, SLT brought the average down to about 19 mmHg at 12 months, with roughly 63% achieving a reduction of 30% or more from their baseline.20Sultan Qaboos University Medical Journal. Efficacy and Safety of Selective Laser Trabeculoplasty as a Primary Procedure for Controlling Intraocular Pressure in Primary Open Angle Glaucoma and Ocular Hypertensive Patients In another study focusing on patients at high risk for progression, SLT significantly reduced mean IOP from about 22 mmHg to the mid-16 to 17 range, and medication use could be reduced alongside it.21PubMed Central. Clinical outcomes following selective laser trabeculoplasty in Afro-Caribbean patients with glaucoma at high risk for progression
SLT can be repeated if its effect wears off over time, and it does not involve cutting into the eye. For someone with a pressure of 23 who prefers not to use daily drops, it is a reasonable conversation to have with your ophthalmologist.
Surgical Options
When drops and laser are not enough, or when glaucoma is progressing despite those treatments, surgery becomes the next consideration. Minimally invasive glaucoma surgeries (MIGS) have expanded the options considerably in recent years. These procedures typically involve placing a tiny device inside the eye to create an additional drainage pathway, bypassing the clogged meshwork.22PubMed Central. The Role of Minimally Invasive Glaucoma Surgery Devices in the Management of Glaucoma They are often combined with cataract surgery, since both procedures address the front part of the eye and can be done in a single session.
Studies comparing cataract surgery alone to cataract surgery plus a MIGS device found that the combined approach produced a sustained pressure reduction of about 4 to 5 mmHg and allowed patients to drop one or more medications, with those benefits holding out to two years.23PubMed Central. Combined phacoemulsification and microinvasive glaucoma surgery in comparison to phacoemulsification alone for open angle glaucoma Complications from the devices were uncommon and resolved quickly. MIGS are best suited for mild to moderate glaucoma; advanced disease with very high pressures may still require traditional filtration surgery, which creates a larger new drainage route but involves more recovery time.
Research Into Protecting the Optic Nerve Directly
Lowering eye pressure is the only proven way to slow glaucoma right now, but researchers have recognized for a long time that it is not always enough. Some patients lose vision despite excellent pressure control, which strongly suggests that factors beyond pressure, including poor blood flow to the nerve, oxidative stress, and metabolic dysfunction, also drive the damage.24PubMed Central. Neuroprotection in glaucoma
This has fueled a growing field of neuroprotection research. Scientists are investigating whether certain compounds can shield the nerve cells directly, independent of what the pressure is doing. Naturally derived substances like nicotinamide (a form of vitamin B3) and citicoline have shown enough promise in early studies to warrant serious clinical investigation.25PubMed Central. Optic Nerve Neuroprotection in Glaucoma: A Narrative Review Several clinical trials testing metabolic-targeted therapies for glaucoma neuroprotection are now underway, and there is genuine hope in the field that the first treatment to protect the optic nerve through something other than pressure lowering could emerge from these efforts.26Molecular Aspects of Medicine. Neuroprotection in glaucoma: Mechanisms beyond intraocular pressure lowering For now, though, these remain experimental. No neuroprotective agent has been approved specifically for glaucoma, and no one should substitute a supplement for proven pressure-lowering treatment.
What to Expect at Your Next Appointment
If you have been told your eye pressure is 23, the most likely scenario is monitoring rather than immediate treatment. Your doctor will probably want to measure your corneal thickness if that has not been done, examine your optic nerve closely using a magnifying lens or imaging equipment, and test your peripheral vision with a visual field exam. These three pieces of information, combined with your pressure readings over multiple visits, paint the picture that determines whether you have ocular hypertension (elevated pressure with no nerve damage), early glaucoma, or simply an unremarkable reading from a high-normal eye.
If everything else looks healthy, you might be asked to return every six to twelve months for monitoring, with no treatment at all. Many people with pressures in the low 20s live their entire lives without developing glaucoma. On the other hand, if the exam reveals suspicious optic nerve findings or thin corneas, treatment could start sooner. The key is not to panic at the number but to follow through on the appointments that let your doctor figure out what the number actually means for your eyes specifically.