Chronic Open-Angle Glaucoma

Chronic, progressive optic neuropathy characterized by irreversible loss of retinal ganglion cells

Aetiology

Primary Open-Angle Glaucoma (POAG)

  • Idiopathic dysfunction of aqueous humor outflow through the trabecular meshwork

Secondary Open-Angle Glaucoma

  • Pseudoexfoliation syndrome
  • Pigment dispersion syndrome
  • Steroid-induced glaucoma
  • Uveitic glaucoma
  • Traumatic glaucoma

Risk Factors

  • Increasing age
  • Family history of glaucoma
  • Elevated intraocular pressure
  • African or Asian ancestry
  • Thin central corneal thickness
  • Myopia
  • Systemic vascular disease (e.g., hypertension, diabetes mellitus)

Clinical presentation

Symptoms

  • Typically asymptomatic in early stages
  • Gradual, painless loss of peripheral vision
  • Central vision affected only in advanced disease

Signs

  • Elevated or normal IOP
  • Open anterior chamber angle on gonioscopy
  • Increased cup-to-disc ratio and asymmetry
  • Neuroretinal rim thinning (inferior and superior first)
  • Retinal nerve fiber layer defects

Investigations

Clinical Examination

  • Measurement of intraocular pressure (tonometry)
  • Slit-lamp examination
  • Gonioscopy (after acute attack resolution)
  • Funduscopy (often limited during acute phase)
    • Nasalization
    • Bayonetting
    • C/D ratio > 0.5
    • Exposed lamina cribrosa
notion image

Management

Medical Therapy (First-Line)

  • Beta-adrenergic blockers (first line DOC)
    • Timolol maleate 0.25-0.5% ED 1-2x/day
    • Betaxolol HCl 0.25% ED 2x/day
    • Levobunolol 0.25-0.5% ED 1-2x/day
    • Carteolol 1% ED 1-2x/day
  • Prostaglandin analogues
    • Latanoprost 0.005% ED 1x/day
    • Bimatoprost 0.03% ED 1x/day
  • Alpha-adrenergic agonists
  • Carbonic anhydrase inhibitors
    • Acetazolamide 250mg PO 3-4x/day
    • Dorzolamide 2% ED 3x/day
  • Combination therapy when required

Laser Therapy

  • Selective laser trabeculoplasty (SLT)
  • Argon laser trabeculoplasty (ALT)

Surgical Therapy

  • Trabeculectomy
  • Glaucoma drainage devices
  • Minimally invasive glaucoma surgery (MIGS)