Glaucoma

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Glaucoma is a group of progressive optic neuropathies characterised by damage to the optic nerve, often associated with raised intraocular pressure (IOP), leading to visual field loss.

Aetiology

  • Primary open-angle glaucoma (POAG): impaired aqueous humour drainage through the trabecular meshwork.
  • Primary angle-closure glaucoma (PACG): sudden blockage of aqueous humour outflow due to a narrow anterior chamber angle.
  • Secondary glaucoma: associated with trauma, steroid use, uveitis, or neovascularisation.
  • Congenital glaucoma: present at birth due to developmental anomalies.

Pathophysiology

  • Raised IOP leads to mechanical compression and reduced perfusion of the optic nerve head.
  • Progressive loss of retinal ganglion cells results in characteristic optic disc cupping.
  • Peripheral vision loss occurs initially, progressing to central vision loss in advanced disease.

Risk Factors

  • Increased age.
  • Family history of glaucoma.
  • Elevated IOP.
  • Myopia (POAG) or hyperopia (PACG).
  • Diabetes mellitus and hypertension.
  • Prolonged corticosteroid use.

Signs and Symptoms

  • Primary open-angle glaucoma: insidious onset, peripheral vision loss, often asymptomatic until advanced stages.
  • Acute angle-closure glaucoma: sudden painful red eye, headache, nausea, blurred vision, and halos around lights.
  • Optic disc cupping: increased cup-to-disc ratio on fundoscopy.
  • Elevated IOP: detected on tonometry.

Investigations

  • Tonometry: measures intraocular pressure (normal range: 10-21 mmHg).
  • Gonioscopy: assesses anterior chamber angle configuration.
  • Optic disc examination: evaluates cup-to-disc ratio.
  • Visual field testing: detects peripheral vision loss.

Management

This is often picked by optometrist. If the suspect open-angle glaucoma they will ref to ophtalmologist (non urgently). Immediate referral (emergency) to an ophthalmologist if acute angle closure glaucoma is suspected e.g. sudden onset severe eye pain, blurred vision, headache, red eye + fixed/mild dilated-pupil + raised intraocular pressure (IOP).

1. Medical Management (done by opthalmology):

  • Prostaglandin analogues: first line treatment (e.g., latanoprost) to increase aqueous outflow.
  • Beta-blockers: (e.g., topical timolol) reduce aqueous humour production.
  • Carbonic anhydrase inhibitors: (e.g., acetazolamide) decrease aqueous production.
  • Alpha-agonists: (e.g., brimonidine) dual action reducing production and increasing outflow.

2. Surgical Management:

  • Laser trabeculoplasty: enhances trabecular outflow in POAG.
  • Laser peripheral iridotomy: first line treatment for PACG.
  • Trabeculectomy: surgical intervention for refractory cases.

3. Lifestyle and Monitoring:

  • Regular IOP monitoring and visual field testing.
  • Patient education on medication adherence.
  • Avoidance of activities that increase IOP (e.g., prolonged head-down positions).

4. Referral:

  • Ophthalmology: all suspected cases require urgent referral.
  • Genetics: if familial glaucoma is suspected.
Eye DiseasesmypanotesGlaucoma