- Acute angle‑closure glaucoma: sudden severe eye pain, headache, nausea, blurred vision, halos around lights – ocular emergency (check IOP >40 mmHg)
- Central retinal vein occlusion: associated with glaucoma – sudden vision loss
- Progression to blindness: advanced glaucoma with severe visual field constriction – refer urgently
Primary Open‑Angle Glaucoma
Must-Not-Miss / Red Flags
Patient Explanation
“You have a condition where pressure inside your eye is slowly damaging the nerve that connects your eye to your brain. It often has no symptoms early on, but eye drops can lower the pressure and protect your vision.”
Board Fact
“The only proven treatment for glaucoma is lowering intraocular pressure, either with medications, laser, or surgery.”
ICD-10
H40.11X0
Definition & Core Concept
Primary open‑angle glaucoma (POAG) is a chronic, progressive optic neuropathy characterized by cupping of the optic disc and visual field loss, associated with elevated intraocular pressure (IOP), although IOP may be normal in some cases (normal‑tension glaucoma).
Epidemiology & Risk Factors
- Leading cause of irreversible blindness worldwide
- Affects 3% of adults >40 years; prevalence increases with age
- Risk factors: elevated IOP, age, African ancestry (3‑5x higher risk), family history, thin central corneal thickness
Pathophysiology (Rule of 3)
- Impaired aqueous humor drainage through the trabecular meshwork → elevated IOP
- Mechanical compression and reduced blood flow at the optic nerve head → retinal ganglion cell apoptosis
- Progressive cupping of the optic disc and characteristic visual field defects (nasal step, arcuate scotoma, paracentral defects)
Clinical Presentation
- Asymptomatic in early stages (vision loss starts peripherally)
- Gradual loss of peripheral vision, tunnel vision in advanced disease
- On fundoscopy: increased cup‑to‑disc ratio (>0.5), vertical elongation of the cup, notching of the neuroretinal rim
Diagnostic Workup
Tonometry: IOP >21 mmHg (but may be normal). Ophthalmoscopy: optic disc cupping. Perimetry (visual field testing): characteristic arcuate or paracentral defects. Gonioscopy: open anterior chamber angle (differentiates from angle‑closure). Pachymetry: central corneal thickness (thin corneas underestimate true IOP). OCT: retinal nerve fiber layer thinning.
Management Protocol
- First‑line: Prostaglandin analogs (Latanoprost 0.005% one drop nightly) – reduce IOP by 25‑30%
- Second‑line: Beta‑blockers (Timolol 0.5% BID), Alpha‑2 agonists (Brimonidine), Carbonic anhydrase inhibitors (Dorzolamide) as add‑on or alternative
- Laser trabeculoplasty: if medications insufficient or non‑compliant
- Trabeculectomy: surgical filtering procedure for refractory glaucoma
- Monitor: IOP check every 3‑6 months, visual fields and OCT annually
Complications & Prognosis
- Irreversible blindness if untreated
- Side effects of medications: ocular irritation, hyperemia, systemic effects with beta‑blockers (bradycardia, bronchospasm)
- Cataract progression (may be accelerated by some medications or surgery)
ICU Criteria
ICU admission not required for POAG; only for acute angle‑closure glaucoma if surgery needed and medical comorbidities.
Clinical Vignette
A 65‑year‑old African American man presents for a routine eye exam. He has no visual complaints. IOP is 26 mmHg in both eyes. Fundoscopy reveals vertical cupping with cup‑to‑disc ratio 0.7 bilaterally. Visual field testing shows early arcuate defects. Gonioscopy confirms open angles. He is started on Latanoprost.
Pearls & Pitfalls
- Glaucoma is asymptomatic until advanced – screening is essential, especially in high‑risk populations (every 1‑2 years after age 40).
- Medication compliance is a major challenge; educate patients that glaucoma is a lifelong condition requiring daily treatment, even without symptoms.
Discharge & Follow-Up
IOP check every 3‑6 months. Annual dilated fundus exam, visual fields, and OCT. Educate on proper eye drop instillation technique.
Literature & Guidelines
AAO 2024 Preferred Practice Pattern on Primary Open‑Angle Glaucoma. PMID: 38691400.