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An estimated 3 million or more Americans have glaucoma, and about half of them do not know it. Recent population studies suggest the true number may be higher than the long-quoted 3 million figure, but the more important point is stable across every estimate: the disease damages the optic nerve, often without symptoms, until peripheral vision is permanently lost. That silent course is what makes routine screening — not just symptom-driven visits — so important after age 40, and even more so after 60.
This guide covers the major types of glaucoma, who is at highest risk, how it is diagnosed using more than just eye pressure, and the full ladder of treatments from drops to selective laser trabeculoplasty (SLT) to minimally invasive surgery (MIGS). For related senior eye topics, our medical conditions library includes companion guides on cataracts and age-related macular degeneration. This article is educational and is not a substitute for care from a qualified eye doctor.
What Glaucoma Is
Glaucoma is a group of optic neuropathies in which retinal ganglion cell axons die at the optic disc, producing characteristic cupping and matching visual field defects. Elevated intraocular pressure (IOP) is the principal modifiable risk factor, but a meaningful share of patients develop nerve damage at “normal” pressures (normal-tension glaucoma), and many people with high pressure never develop disease (ocular hypertension). The American Academy of Ophthalmology emphasizes that glaucoma is fundamentally a nerve disease, not just a pressure problem. Lowering pressure is currently the only proven way to slow it, which is why so much of diagnosis and treatment revolves around IOP even though pressure is not the whole story.
The Major Types
Primary open-angle glaucoma (POAG) is the most common form in the US, accounting for roughly 90% of adult cases. The drainage angle remains anatomically open, but aqueous humor outflow through the trabecular meshwork slows, raising IOP. Damage progresses over years, usually painlessly.
Angle-closure glaucoma occurs when the iris physically blocks the drainage angle. It can be chronic or acute. Acute angle closure is a vision-threatening emergency: the cornea suddenly clouds, IOP spikes above 40 mmHg, and the eye becomes red and rock-hard. Other forms include normal-tension glaucoma (optic nerve damage with IOPs in the typical range), pigmentary, pseudoexfoliative, neovascular, uveitic, and traumatic glaucomas. There is also congenital and childhood glaucoma, which is rare but requires urgent specialist care.
When to seek emergency care: Call 911 or go to the nearest emergency room right away for severe eye pain with nausea, vomiting, blurred vision, headache, and halos around lights. These are classic symptoms of acute angle-closure glaucoma — vision loss can become permanent within hours without urgent IOP-lowering treatment. Do not wait to see whether the symptoms pass on their own.
Risk Factors
Age over 60, Black or Hispanic ancestry (with earlier onset and faster progression in Black Americans), family history of glaucoma, high myopia, thin central corneal thickness, low ocular perfusion pressure, sleep apnea, prior eye injury, and long-term steroid use (drops, pills, or inhalers) all raise risk. The National Eye Institute recommends comprehensive dilated exams every one to two years for higher-risk groups — Black Americans over 40, Hispanic/Latino adults over 60, and anyone with a family history — and notes that anyone can develop glaucoma, so it is worth asking your eye doctor what interval is right for you. Having a risk factor does not mean you will develop the disease, and having none does not guarantee you will not.
Symptoms — Or the Lack of Them
Open-angle glaucoma is famously asymptomatic until late. Peripheral vision narrows so gradually that patients adapt without noticing. By the time someone reports bumping into doorframes or missing cars in adjacent lanes, substantial nerve damage is already done. This is why routine screening is the only reliable way to catch early disease, and why glaucoma is sometimes called “the silent thief of sight.”
Acute angle closure is the opposite — abrupt severe pain, nausea, vomiting, halos, and rapidly blurring vision. Patients sometimes mistake it for migraine or stomach flu and lose hours that matter. Chronic angle closure can mimic open-angle disease with no symptoms at all, which is one reason a dilated exam that checks the drainage angle matters even when your eyes feel fine.
How Glaucoma Is Diagnosed
Tonometry measures IOP. Gonioscopy assesses whether the drainage angle is open or narrow. Optical coherence tomography (OCT) of the retinal nerve fiber layer and ganglion cell complex provides quantitative imaging that detects structural loss before visual field changes appear. Standard automated perimetry (visual field testing) maps functional defects. Pachymetry corrects IOP readings for corneal thickness — a thin cornea inflates risk. Photographs or scans of the optic disc give a baseline to compare against over time.
No single test diagnoses glaucoma. The pattern across structure (OCT, optic disc photography), function (visual field), and pressure over multiple visits guides the diagnosis. Many patients are followed as “glaucoma suspects” for months or years before a formal diagnosis is made, and that watchful monitoring is itself good care rather than a delay.
Treatment: Lowering Pressure
Every approved glaucoma therapy works by lowering IOP. The Ocular Hypertension Treatment Study and the Early Manifest Glaucoma Trial both showed that each 1 mmHg of pressure reduction reduces progression risk by roughly 10%. Your ophthalmologist sets a “target pressure” for each eye based on how much damage is present and how fast it is changing, then adjusts treatment to reach it.
Prostaglandin analogs (latanoprost, bimatoprost, travoprost, tafluprost) are typical first-line drops. They lower IOP about 25 to 33% with once-daily dosing and are generally well tolerated, though they can darken the iris, lengthen lashes, and cause periocular skin changes. Beta blockers (timolol), alpha agonists (brimonidine), carbonic anhydrase inhibitors (dorzolamide, brinzolamide), and Rho kinase inhibitors (netarsudil) serve as add-ons or alternatives. Adherence to drops is poor — often below 50% at one year — and is the most common reason for “treatment failure.” These are prescriber-directed medicines: do not start, stop, or change a glaucoma drop on your own, because pressure can climb silently the moment a drop is discontinued.
Selective laser trabeculoplasty (SLT) is increasingly used as first-line therapy. The 2019 LiGHT trial showed SLT was at least as effective as drops over six years, with fewer escalations to surgery and less reliance on daily medication. SLT is a roughly five-minute office laser procedure, repeatable, and covered by Medicare. Whether drops or laser is the better starting point is a decision to make with your ophthalmologist, weighing side effects, cost, and how reliably you can use daily drops.
Surgery and Minimally Invasive Options
When drops and laser do not control pressure adequately, surgical options include traditional trabeculectomy, glaucoma drainage devices (Ahmed, Baerveldt), and a growing class of MIGS — minimally invasive glaucoma surgeries. MIGS devices such as the iStent inject, Hydrus Microstent, and Xen Gel Stent are typically combined with cataract surgery in patients with mild-to-moderate disease and offer modest IOP reduction with a much better safety profile than trabeculectomy. Cataract surgery alone often lowers IOP by 2 to 4 mmHg in glaucoma patients, which is one reason ophthalmologists are sometimes proactive about cataract surgery in this group. The field is evolving quickly, and which procedure fits depends on your glaucoma type, severity, and eye anatomy — your ophthalmologist decides, not a checklist.
For acute angle closure, the standard is laser peripheral iridotomy plus IOP-lowering medications to break the attack. Eyes at anatomical risk for angle closure may receive a prophylactic iridotomy before an attack ever happens.
Glaucoma Treatment at a Glance
| Step | Commonly considered options |
|---|---|
| First-line | Prostaglandin analog drops or SLT laser (both lower pressure roughly 25-33%) |
| Add-on medicines | Beta blockers, alpha agonists, carbonic anhydrase inhibitors, Rho kinase inhibitors, combination drops |
| Procedural, milder disease | SLT (repeatable); MIGS such as iStent, Hydrus, or Xen, often at cataract surgery |
| Advanced or uncontrolled | Trabeculectomy or drainage-device (Ahmed, Baerveldt) surgery |
| Acute angle-closure emergency | Urgent IOP-lowering medication plus laser peripheral iridotomy |
This table is a general overview, not a treatment plan. The right choice depends on your glaucoma type, target pressure, and eye anatomy, and should be decided with your ophthalmologist.
Living With Glaucoma
Glaucoma is chronic. Adherence to drops, regular pressure checks every three to four months in moderate disease, and visual field testing once or twice a year are the routine. Driving safety hinges on visual field rather than central acuity — the DMV in most states requires a minimum field for unrestricted licensure. Falls and fractures are more common in glaucoma patients with peripheral visual field loss; our overview of social isolation in older adults touches on the cascade from sensory loss to disengagement. Simple habits help: set phone reminders for drops, keep a spare bottle, ask about preservative-free formulations if your eyes sting, and bring every eye medication to each visit so your team can check the full list.
Frequently Asked Questions
Can vision lost to glaucoma come back?
No. Damaged retinal ganglion cells do not regenerate. Treatment preserves remaining vision; it does not restore what has been lost. Early diagnosis is the only meaningful way to keep usable vision into late life.
Are eye pressure readings the only thing that matter?
No. About one-third of glaucoma patients have IOPs in the statistically “normal” range. The optic nerve appearance, OCT measurements, and visual field tell the story. Pressure is simply the one knob doctors can currently turn to slow the disease.
Is marijuana an effective glaucoma treatment?
It lowers IOP for only about three to four hours, requiring near-continuous use to be therapeutic, and it can lower blood pressure to the optic nerve. The AAO does not recommend cannabis for glaucoma because available eye drops, laser, and surgery are far more effective with fewer side effects.
How often should I be screened if I have a family history?
The AAO suggests baseline comprehensive eye exams beginning around age 40 for adults with first-degree relatives who have glaucoma, then every one to two years depending on findings. After 60, screening every one to two years is reasonable for most people. Ask your eye doctor to set an interval based on your specific risk.
Will I go blind from glaucoma?
Most people diagnosed and treated today keep functional vision for life. Blindness is far more likely when the disease is caught late or when drops are not used consistently. That is exactly why routine exams and faithful treatment matter so much — the outcome depends heavily on catching it early and staying in care.
Quick summary: Glaucoma is a group of optic-nerve diseases, usually painless in its early stages, that can cause permanent vision loss if untreated. Elevated eye pressure is the main treatable risk factor, but normal pressure does not rule it out. Treatment — prescriber-directed drops, SLT laser, or surgery/MIGS — lowers pressure to slow damage; do not start or stop drops on your own. Sudden severe eye pain, headache, nausea, and halos can signal an acute angle-closure emergency, so seek care immediately. Routine dilated eye exams are the best protection, and your ophthalmologist should tailor screening and treatment to you. This article is educational and not a substitute for professional medical care.
The Bottom Line
Glaucoma steals vision quietly. The defenses against it are routine dilated exams, OCT and visual field monitoring, faithful adherence to prescriber-directed drops or willingness to consider SLT, and treating angle-closure symptoms as the emergency they are. Black, Hispanic, and family-history populations need earlier and more frequent screening. With consistent IOP control, most patients diagnosed today will keep functional vision for the rest of their lives — but only if the disease is caught and treated before a large share of the optic nerve fibers are gone. Use this guide to prepare questions for your ophthalmologist rather than as a replacement for a personal exam.