Roughly 3 million Americans have glaucoma, and about half of them do not know it. 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 AMD.
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.
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.
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.
When to seek emergency care: Call 911 or go to the nearest emergency room 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 be permanent within hours without urgent IOP-lowering treatment.
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, and long-term steroid use all raise risk. The National Eye Institute recommends comprehensive dilated exams every one to two years for all adults 60 and older, and earlier if first-degree relatives have glaucoma.
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.
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.
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.
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” before formal diagnosis.
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 about 10%.
Prostaglandin analogs (latanoprost, bimatoprost, travoprost, tafluprost) are typical first-line drops. They lower IOP 25 to 33% with once-daily dosing and are 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.”
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. SLT is a 5-minute office laser procedure, repeatable, and covered by Medicare.
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 like 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 2 to 4 mmHg in glaucoma patients, which is one reason ophthalmologists are sometimes proactive about cataract surgery in this group.
For acute angle closure, the standard is laser peripheral iridotomy plus IOP-lowering medications. Eyes at anatomical risk for angle closure may receive prophylactic iridotomy.
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.
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 the one knob doctors can turn.
Is marijuana an effective glaucoma treatment?
It lowers IOP for about three to four hours, requiring near-continuous use to be therapeutic. 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 recommended for everyone.
The Bottom Line
Glaucoma steals vision quietly. The defenses against it are routine dilated exams, OCT and visual field monitoring, faithful adherence to 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 half the optic nerve fibers are gone.