Pressure inside your eyes is created by a clear fluid that continuously fills and drains from the front of each eye. When production and drainage are in balance, pressure stays in the normal range of 10 to 20 mmHg. When something slows drainage or increases production, pressure climbs. The causes range from temporary lifestyle triggers to chronic medical conditions, and understanding them can help you protect your vision long-term.
How Eye Pressure Works
Your eye constantly produces a clear fluid called aqueous humor. This isn’t the same as tears; it flows inside the eye, nourishing the lens and cornea and helping the eye hold its shape. The fluid is made by a ring of tissue behind the iris called the ciliary body, which filters components from your blood into the eye in a process closely tied to your overall blood flow.
Once produced, the fluid flows through the pupil into the front chamber of the eye and drains out through two main routes. The primary path runs through a mesh-like filter where the iris meets the cornea, then into a tiny canal and eventually into your bloodstream. A secondary path drains fluid through deeper tissues in the eye wall. Think of it like a sink: the faucet is always running at a slow, steady rate. As long as the drain keeps up, the water level stays stable. Eye pressure rises when the drain gets partially clogged or when the faucet runs faster than usual.
Glaucoma and Drainage Problems
The most well-known cause of elevated eye pressure is glaucoma, a group of conditions that damage the optic nerve. In the most common form, open-angle glaucoma, the drainage mesh gradually becomes less efficient over years. Pressure rises so slowly that most people feel nothing until significant vision loss has already occurred.
Angle-closure glaucoma works differently. The iris bulges forward and physically blocks the drainage angle, sometimes partially and sometimes completely. When the blockage happens suddenly, pressure can spike dramatically, causing severe eye pain, headache, nausea, and blurred vision. This is an emergency that requires immediate treatment to prevent permanent damage.
In pigmentary glaucoma, tiny granules of pigment flake off the back of the iris and clog the drainage filter. Physical activity like jogging can shake loose more of these granules, causing temporary pressure spikes on top of a gradually worsening baseline. Pseudoexfoliation syndrome follows a similar pattern: flaky material produced by the lens and other structures accumulates in the drainage pathway.
Medications That Raise Eye Pressure
Corticosteroids are the most common medication-related cause of elevated eye pressure. About one-third of the general population are “steroid responders,” meaning their eye pressure rises after using corticosteroids for two weeks or more. For people who already have open-angle glaucoma, that number jumps to over 90%. This applies to steroid eye drops, nasal sprays, inhalers, and oral or injected steroids. The effect is typically reversible once the medication is stopped, but prolonged use can cause lasting damage to the drainage system.
Eye Injuries and Inflammation
A blow to the eye, even one that seems minor, can raise pressure through several mechanisms. The impact can tear or distort the drainage mesh, cause bleeding into the front chamber of the eye (called a hyphema), or trigger inflammation that disrupts the normal fluid barrier between blood vessels and the eye’s interior. Some of these effects show up immediately, while others develop months or years later. Angle recession, where trauma permanently widens and scars the drainage angle, can cause delayed pressure increases that appear long after the original injury has healed.
Systemic Health Conditions
What happens in the rest of your body affects your eyes more than most people realize. High blood pressure changes blood flow through the ciliary body, which can alter how much fluid the eye produces. Research using genetic analysis has confirmed that hypertension is an independent risk factor for eye-related complications, and that when high blood pressure and elevated eye pressure occur together, the combined risk is greater than either one alone.
Diabetes is another established risk factor. Insulin resistance and fluctuating blood sugar levels affect the small blood vessels throughout the eye, and diabetes appears on the list of recognized risk factors for open-angle glaucoma alongside elevated pressure itself, older age, and family history.
Yoga, Exercise, and Body Position
Any position that puts your head below your heart temporarily raises eye pressure. A study measuring pressure during four common yoga poses found that downward-facing dog increased eye pressure by roughly 70 to 80 percent, pushing average readings from about 17 mmHg to nearly 29 mmHg within two minutes. A standing forward bend raised pressure by about 50 to 60 percent. Even a relatively gentle legs-up-the-wall pose produced a 23 to 25 percent increase.
These spikes occurred in both healthy participants and those with glaucoma, and the size of the increase was similar in both groups. Pressure returned to normal after the pose ended. For most people, these brief fluctuations are harmless. But if you already have elevated baseline pressure or glaucoma, repeated large spikes may contribute to optic nerve damage over time. Headstands and prolonged inverted positions carry the highest risk.
Corneal Thickness and Misleading Readings
Sometimes the issue isn’t actual pressure but how it’s measured. The standard pressure test (tonometry) pushes against the surface of your cornea, and the thickness of that cornea affects the reading. A thicker-than-average cornea makes pressure appear higher than it really is, while a thinner cornea makes it appear lower. The difference is not trivial: a cornea that’s 100 microns thicker than average can inflate your reading by about 4 to 5 mmHg, potentially turning a normal result into one that looks concerning. A thin cornea can mask genuinely elevated pressure.
This is why many eye doctors measure corneal thickness as part of a comprehensive exam, especially when a pressure reading comes back borderline. If your corneas are unusually thick or thin, your doctor can apply a correction factor to get a more accurate picture of your true pressure.
Who Is at Higher Risk
Several factors increase the likelihood of developing elevated eye pressure or glaucoma. African Americans are six to eight times more likely to develop glaucoma than white people and tend to develop it about 10 years earlier than other ethnic groups. Hispanic and Asian populations also face elevated risk. After age 60, the risk rises significantly for everyone regardless of ethnicity. A family history of glaucoma is another strong predictor, as are nearsightedness, a thinner cornea, and diabetes.
Ocular hypertension, the term for elevated eye pressure without any detectable nerve damage, affects a significant number of people and doesn’t always progress to glaucoma. But it does require monitoring, because the higher the pressure and the more risk factors present, the greater the chance of eventual optic nerve damage and vision loss. Regular comprehensive eye exams that include pressure measurement, optic nerve evaluation, and visual field testing are the most reliable way to catch problems early, before you notice any symptoms yourself.