Open-angle glaucoma is the most common form of glaucoma, a condition where pressure builds inside the eye and gradually damages the optic nerve. Normal eye pressure falls between 10 and 20 mmHg, and in open-angle glaucoma, that pressure rises because fluid can’t drain efficiently, even though the drainage channel appears structurally open. It’s often called the “silent thief of sight” because most people don’t notice symptoms until they’ve already lost significant vision.
Why Pressure Builds in the Eye
Your eye constantly produces a clear fluid that nourishes its internal structures and then drains out through a mesh-like tissue near the base of the iris. In open-angle glaucoma, this drainage tissue develops microscopic problems: cells die off, excess structural material accumulates, and the internal scaffolding stiffens. The result is like a clogged filter. Fluid keeps flowing in at the normal rate, but it can’t get out fast enough, so pressure climbs.
The term “open angle” distinguishes this from narrow-angle glaucoma, where the drainage channel is physically blocked or too narrow. In open-angle glaucoma, the channel looks fine on examination. The resistance is hidden deeper within the tissue itself, which is part of why the condition is so easy to miss without proper testing.
How Vision Loss Happens
Elevated pressure slowly destroys nerve fibers at the back of the eye where the optic nerve connects. Vision loss starts at the outer edges of your visual field, your peripheral vision, and gradually closes inward toward the center. Because it happens so slowly and affects side vision first, your brain compensates remarkably well. You might not realize anything is wrong until a substantial portion of your visual field is gone. This damage is permanent. Lost nerve fibers don’t regenerate, which makes early detection critical.
Who Is Most at Risk
Age is the single biggest risk factor. Everyone over 60 faces elevated risk, but certain groups need to pay attention much earlier. African Americans are six to eight times more likely to develop glaucoma than white people and tend to develop it about 10 years sooner than other ethnic groups. After cataracts, glaucoma is the leading cause of blindness among African Americans, which is why comprehensive eye exams are recommended starting at age 35 for this group. Hispanic and Asian populations also carry higher risk.
Family history matters significantly. Having a parent or sibling with glaucoma increases your odds. Diabetes is another independent risk factor. Certain subtypes affect specific populations: one form is more common in people of northern European descent, and another can affect young, otherwise healthy people who are nearsighted.
How It’s Diagnosed
A standard vision test won’t catch glaucoma. Diagnosis requires a set of specialized measurements that together paint a picture of your eye’s internal health.
- Tonometry measures the pressure inside your eye. This is the “puff of air” test many people associate with eye exams, though newer methods use a gentle probe instead.
- Pachymetry measures corneal thickness, which matters because a thicker cornea can make pressure readings appear artificially high, while a thinner cornea can mask genuinely elevated pressure. Typical corneal thickness in the U.S. runs between 540 and 550 micrometers. Your provider uses your corneal thickness to interpret your pressure reading more accurately.
- Optical coherence tomography (OCT) creates a detailed cross-sectional image of your optic nerve and the nerve fiber layer at the back of your eye. This can detect thinning before you notice any change in your vision.
- Visual field testing maps your peripheral vision to identify blind spots you may not be aware of.
No single test confirms glaucoma. Your eye care provider looks at the full picture, including how your results change over time. That’s why routine comprehensive eye exams (not just vision checks for glasses) are the main line of defense.
Treatment Options
All current treatments focus on lowering eye pressure, since that’s the only modifiable factor proven to slow nerve damage. The goal is to preserve the vision you still have.
Eye Drops
Prescription eye drops are the most common first-line treatment. Different types work in different ways. Some increase the rate at which fluid drains from the eye. Others reduce the amount of fluid your eye produces in the first place. Some do both. Your provider will typically start with one type and adjust based on how well your pressure responds and whether side effects are manageable. Most people use drops once or twice daily, indefinitely.
Laser Treatment
A procedure called selective laser trabeculoplasty uses targeted light pulses to improve drainage through the meshwork tissue. It’s done in an office setting and takes only a few minutes. Studies show it reduces eye pressure by an average of about 27% in the weeks following treatment. For many people this is enough to replace or reduce daily eye drops, at least for a period of time. The effect can wear off over months or years, but the procedure can often be repeated.
Surgery
When drops and laser treatment aren’t enough, surgical options create new drainage pathways or implant tiny devices to keep fluid moving out of the eye. Recovery varies depending on the approach, but most people return to normal activities within a few weeks. Surgery doesn’t restore lost vision. It aims to stabilize pressure and prevent further damage.
Lifestyle Factors That Affect Eye Pressure
Regular aerobic exercise tends to lower eye pressure modestly, which is one reason staying physically active is encouraged. However, caffeine can work against this benefit. Research shows that caffeine causes a short-term spike in eye pressure in both healthy people and those with glaucoma. In one study, drinking caffeine before low-intensity exercise completely canceled out the pressure-lowering effect of the workout. If you have glaucoma or are at high risk, limiting caffeine intake is a reasonable precaution.
Sleep position also plays a role. Lying flat or face-down can raise eye pressure compared to sleeping with your head slightly elevated. Some providers recommend using a wedge pillow, particularly for people whose glaucoma is more advanced in one eye, since the eye closest to the pillow (the “down” eye) tends to experience higher pressure overnight.
Long-Term Outlook With Treatment
The prognosis for open-angle glaucoma has improved dramatically. Between the 1960s and the early 2000s, the likelihood of losing sight in one eye dropped from 28% to 13.5%, largely due to better diagnostic imaging and more treatment options, including the development of laser procedures. Left completely untreated, glaucoma will erode peripheral vision over years and can eventually cause blindness. With consistent treatment and monitoring, most people retain functional vision for life.
The key variable is timing. Because the disease is painless and vision loss is irreversible, the people who do best are those who catch it early through routine eye exams, before they ever notice a problem. Treatment can’t undo damage already done, but it’s highly effective at slowing or stopping further loss once it begins.