Chronic painless optic neuropathy with progressive visual field loss — leading cause of irreversible blindness worldwide.
Also known as: POAG, open-angle glaucoma, primary open-angle glaucoma, chronic glaucoma
Overview
Chronic, progressive, typically bilateral optic neuropathy characterized by retinal nerve fiber layer loss, characteristic optic disc cupping, and corresponding visual field defects, occurring in the presence of an open anterior chamber angle. Elevated intraocular pressure (IOP) is the most important modifiable risk factor, although normal-tension glaucoma occurs with IOP in the statistically normal range (<21 mmHg).
Epidemiology
Leading cause of irreversible blindness worldwide. Prevalence rises sharply with age — ~1% at age 40, ~10% by age 80. African ancestry: 3-4× risk and earlier onset; Hispanic ancestry also elevated. Approximately half of affected patients are undiagnosed.
Try two board-style Primary Open-Angle Glaucoma questions
Real questions from the FirstPassPA bank, with the full explanation. Pick an answer — no signup, no email.
Question 1EENTMedium
A 68-year-old man has painless, progressive loss of peripheral vision. Intraocular pressure is 28 mmHg, and funduscopy shows a cup-to-disc ratio of 0.8 with optic disc cupping. Which of the following is the most appropriate first-line treatment?
AAcetazolamide
BDorzolamide-timolol
CPilocarpine
DAnti-VEGF intravitreal injection
ELatanoprost
Reveal answer & full explanation
Correct answer: E — Latanoprost
AAcetazolamide
BDorzolamide-timolol
CPilocarpine
DAnti-VEGF intravitreal injection
ELatanoprost✓
Why Latanoprost is correct
Painless progressive peripheral (tunnel) vision loss with elevated intraocular pressure and an enlarged cup-to-disc ratio of 0.8 indicates primary open-angle glaucoma
A topical prostaglandin analog such as latanoprost is first-line: once-daily dosing and the greatest IOP-lowering effect by increasing uveoscleral outflow
Lowering intraocular pressure is the only proven way to slow optic-nerve damage and visual-field loss
Beta-blockers (timolol) and selective laser trabeculoplasty are alternatives, but among these options latanoprost is the appropriate first-line agent
Why the others are wrong
Acetazolamide — an oral carbonic anhydrase inhibitor that lowers IOP by reducing aqueous humor production, but systemic adverse effects (paresthesias, fatigue, hypokalemia, metabolic acidosis, kidney stones) limit it to short-term use such as acute angle-closure, not first-line chronic therapy for open-angle glaucoma; the systemic-drug-for-a-chronic-disease trap
Pilocarpine — a miotic that lowers pressure but is reserved for angle-closure and seldom used first-line in open-angle disease because of brow ache and miosis; the right-disease-wrong-drug trap
Anti-VEGF intravitreal injection — used for neovascular conditions such as wet macular degeneration and diabetic retinopathy, not glaucoma; buzzword-match on an intravitreal therapy
Dorzolamide-timolol — a fixed combination of a topical carbonic anhydrase inhibitor and a beta-blocker, tempting given the advanced cupping, but initial medical therapy is usually a single agent, most often a prostaglandin analog, with a second drug added if the target IOP is not reached; starting both at once adds timolol's systemic risks such as bradycardia and bronchospasm before monotherapy has been tried; the start-with-combination trap
Question 2EENTMedium
A 60-year-old female with longstanding open-angle glaucoma has progressive visual field loss despite treatment with latanoprost (prostaglandin analogue). Intraocular pressure is 22 mmHg (target below 18). She has no drug allergies. Which of the following medications is the most appropriate to add to better control her intraocular pressure (IOP)?
APilocarpine
BSystemic acetazolamide
CTopical timolol
DTopical atropine
ETopical bimatoprost
Reveal answer & full explanation
Correct answer: C — Topical timolol
APilocarpine
BSystemic acetazolamide
CTopical timolol✓
DTopical atropine
ETopical bimatoprost
Why Topical timolol is correct
Open-angle glaucoma therapy is stepwise, targeting IOP reduction generally 20-30% below baseline and individualized
Prostaglandin analogues (latanoprost, bimatoprost, travoprost, tafluprost) are first-line, reducing IOP 25-35% by increasing uveoscleral outflow
Adding topical timolol (beta-blocker) reduces aqueous production for an additional 20-25% IOP reduction; side effects include bradycardia, bronchospasm, and depression
Why the others are wrong
Pilocarpine — rarely used due to miosis and brow ache; not a preferred add-on (outdated-agent)
Systemic acetazolamide — reserved for short-term use due to systemic side effects; not first choice for chronic add-on therapy (right-class-wrong-setting)
Topical atropine — a mydriatic/cycloplegic that raises IOP and is contraindicated in glaucoma (wrong-direction)
Topical bimatoprost — a more potent prostaglandin analogue looks like a logical step up, but adding a second prostaglandin analogue to latanoprost gives no additive IOP lowering because both increase uveoscleral outflow by the same mechanism (same-mechanism duplication)
Additional high-yield points
Other second-line add-ons: dorzolamide (topical carbonic anhydrase inhibitor) for 15-20% reduction; brimonidine (alpha-2 agonist) for 20-25% reduction (caution in children due to apnea)
A second prostaglandin analogue offers no additive effect (same mechanism)
Selective laser trabeculoplasty (SLT) is non-inferior to medical therapy as first-line (LiGHT trial)
That's 2. Get 7,700+ more.
Unlock the full FirstPassPA bank: 7,700+ board-style questions, flashcards, and an AI tutor that explains every answer. Your 7-day free trial includes everything, and there's no credit card required.
You've read your 2 free diagnosis previews. Create your free account to unlock the full Primary Open-Angle Glaucoma (POAG) outline — plus all 514 diagnoses, 7,700+ board-style questions, flashcards, and an AI tutor. Your 7-day free trial includes everything, and there's no credit card required.
Family history of glaucoma in first-degree relative
Elevated IOP
Thin central corneal thickness
High myopia
Diabetes mellitus, hypertension, sleep apnea
Long-term topical or systemic corticosteroid use
Pathophysiology
Imbalance between aqueous humor production by the ciliary body and outflow through the trabecular meshwork/Schlemm canal increases IOP, which damages retinal ganglion cell axons at the lamina cribrosa. Ischemic and mechanical factors contribute. The optic disc develops progressive cupping (loss of neuroretinal rim) and the visual field loses peripheral and arcuate function before central vision. In normal-tension glaucoma, vascular dysregulation and lower CSF pressure may produce the same end-organ damage at lower IOP.
Clinical presentation
Symptoms
Asymptomatic in early disease — vision loss is painless and gradual
Patients rarely notice peripheral field defects until advanced
Trouble with night driving, missing steps, or bumping into things
Central vision preserved until late
Frequently detected on screening exam or as 'large cup' on routine fundoscopy
Signs / physical exam
Elevated IOP on tonometry (most have IOP >21, but normal-tension subgroup does not)
Open angle on gonioscopy
Optic disc cupping: cup-to-disc ratio >0.6, asymmetric C/D between eyes >0.2, notching of the rim, disc hemorrhages (Drance hemorrhages)
Loss of retinal nerve fiber layer on OCT
Visual field defects: nasal step, paracentral or arcuate scotoma, eventually tunnel vision
Pupils equal with no RAPD until advanced asymmetric disease
Classic findings
Progressive optic disc cupping with corresponding nerve fiber bundle visual field defects in a patient with elevated IOP.
Differential diagnosis
Normal-tension glaucoma — POAG phenotype with IOP <21; consider vascular dysregulation; treat to lower IOP and address risk factors
Secondary glaucomas (pigmentary, pseudoexfoliative, steroid-induced, neovascular, uveitic, traumatic) — Findings on slit lamp/gonioscopy; treat underlying cause
Non-glaucomatous optic neuropathy (ischemic, compressive, inflammatory) — Pale rather than cupped disc, RAPD, sudden vision change, neuroimaging
Optic disc drusen / physiologic cupping — Stable disc and field over time; B-scan or OCT shows drusen
Retinal disease causing field loss — Macular or peripheral retinal pathology; normal disc
Diagnostic workup
Diagnostic criteria
Characteristic optic disc and/or nerve fiber layer damage with corresponding visual field defect in an eye with open angle, after exclusion of secondary causes.
POAG is painless and asymptomatic until advanced — USPSTF (2022) finds insufficient evidence (I statement) for glaucoma screening of asymptomatic adults in primary care, but high-risk patients (African ancestry ≥40, family history, older age) should be referred for a comprehensive dilated eye exam per AAO.
Cup-to-disc ratio asymmetry >0.2 between eyes is suspicious for glaucoma even with normal IOP.
Disc (Drance) hemorrhages at the rim are a strong sign of progression.
Central corneal thickness influences applanation tonometry — thin corneas under-read IOP and confer independent risk (OHTS).
Prostaglandin analogs are the most powerful single-agent IOP lowerers and are once-daily — first-line pharmacotherapy.
Selective laser trabeculoplasty (SLT) is now considered a reasonable first-line option per the LiGHT trial — fewer drops, fewer side effects.
Normal-tension glaucoma still benefits from IOP lowering (CNTGS) — do not dismiss because IOP is 'normal.'
References
AAO 2026 — Gedde SJ, Bowden EC, Challa P, et al. Primary Open-Angle Glaucoma Preferred Practice Pattern. Ophthalmology 2026;133(4):P1-P103
OHTS — Kass MA et al. The Ocular Hypertension Treatment Study. Arch Ophthalmol 2002;120(6):701-713
EMGT — Heijl A et al. Reduction of intraocular pressure and glaucoma progression: Early Manifest Glaucoma Trial. Arch Ophthalmol 2002;120(10):1268-1279
LiGHT — Gazzard G et al. Selective laser trabeculoplasty versus eye drops for first-line treatment of ocular hypertension and glaucoma (LiGHT): a multicentre randomised controlled trial. Lancet 2019;393(10180):1505-1516
CNTGS — Collaborative Normal-Tension Glaucoma Study Group. Comparison of glaucomatous progression between untreated patients with normal-tension glaucoma and patients with therapeutically reduced intraocular pressures. Am J Ophthalmol 1998;126(4):487-497
USPSTF 2022 — US Preventive Services Task Force. Screening for Primary Open-Angle Glaucoma: US Preventive Services Task Force Recommendation Statement. JAMA 2022;327(20):1992-1997
Practice EENT questions on FirstPassPA
Turn this outline into retention. 7,700+ board-style questions with an AI tutor that explains every answer — free to start, no card required.
Educational use only. This outline is a study aid for PA students and is not medical advice or a substitute for clinical judgment. FirstPassPA is an independent study tool and is not affiliated with, endorsed by, or sponsored by NCCPA or PAEA. PANCE® and PANRE® are registered trademarks of the National Commission on Certification of Physician Assistants; End of Rotation™ is a program of the Physician Assistant Education Association.