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Acute Angle-Closure Glaucoma

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Overview

Normally, intraocular pressure is maintained by the flow of aqueous humour. The ciliary body secretes fluid into the posterior chamber, which flows to the iris and through the pupil into the anterior chamber. The fluid then leaves through the trabecular meshwork or uveoscleral outflow routes. The angle is the part of the eye where the iris meets the cornea and sclera and the trabecular meshwork is found here.

Acute angle closure glaucoma (AACG) is where the angle closes acutely. This means that there is a blockage in aqueous drainage leading to increased intraocular pressure and its signs and symptoms. Angle-closure glaucoma can be more chronic, however, this chapter will discuss AACG.

AACG is a medical emergency. Diagnosis and treatment must be quick to save eyesight and prophylaxis is essential to prevent an episode in the other eye.

Epidemiology

  • Prevalence increases with age
  • More common in women than men
  • Occurs most frequently in the 60s-70s

Risk Factors

  • Hypermetropia
    • AACG is rare in people with myopia
  • Increasing age
  • Female sex
  • Asian ethnicity
  • Family history

Presentation

  • Severe pain – this may be around the orbit or similar to a generalised headache
    • Some people have surprisingly little pain
    • Activities that cause mydriasis can worsen the pain e.g. going into a dark room
  • Blurred vision
  • Coloured halos around lights
  • Malaise
  • Nausea and vomiting
  • Red eyes
  • Corneal oedema
  • Fixed and dilated pupil
  • Elevated intraocular pressure
  • Eye feels hard on palpation

Differential Diagnoses

Primary open-angle glaucoma

  • Onset is more chronic
  • Gonioscopy shows an open angle
  • Patients are not systemically unwell
  • Eye redness is absent

Scleritis

  • Usually no systemic upset e.g. nausea/vomiting
  • There may be a history of autoimmune diseases such as rheumatoid arthritis
  • Intraocular pressure normal
  • Gonioscopy shows an open angle

Investigations

  • Immediate referral (within 24 hours) to ophthalmology
  • Tonometry:
    • Confirms elevated intraocular pressure
  • Gonioscopy:
    • Definitive test for diagnosing AACG
    • Confirms angle closure and the trabecular meshwork is not visible
  • Slit-lamp examination:
    • Examines optic disc
    • Shows signs of glaucoma e.g. large optic cup
  • Visual field testing
    • To assess the extent of visual field damage

Management

Primary care

  • 1st-line: urgently refer to ophthalmology
  • If immediate admission is not possible:
    • Lie the person flat with the head not supported by pillows to relieve pressure
    • Give pilocarpine + acetazolamide eyedrops until admission is possible

Management in secondary care

  • 1st-line: Rapidly decrease the intraocular pressure – done by combination treatments using the following agents:
    • Beta-blocker eyedrops (e.g. timolol):
      • Decreases aqueous humour production
    • Cholinergic eyedrops (e.g. pilocarpine):
      • Causes ciliary muscle contraction which opens up drainage channels in the trabecular meshwork
    • Alpha-2 agonist eyedrops (e.g. brimonidine or apraclonidine):
      • Reduces aqueous secretion and increases outflow through the trabecular meshwork
    • IV carbonic anhydrase inhibitor (e.g. acetazolamide)
      • Reduces aqueous secretion by the ciliary body
  • If no response to the above then consider systemic hyperosmotics e.g. IV mannitol
  • Offer analgesia and antiemetics if indicated
  • Definitive treatment: peripheral iridectomy:
    • A laser is used to create a small hole in the peripheral iris promoting aqueous humour flow to the angle

Monitoring

  • After an acute episode, patients with optic neuropathy are generally followed up every 3-6 months to ensure their intraocular pressure is controlled and there are no further signs of glaucoma
  • Patients without optic neuropathy are usually followed up every 6-12 months

Patient Advice

  • Patients should attend follow-ups regularly and be safety-netted on the signs and symptoms of another attack. They should immediately seek help should the signs and symptoms arise.

Complications

  • Retinal artery or vein occlusion:
    • Due to raised intraocular pressure
  • Permanent reduction in visual acuity
  • Loss of vision
  • Attack in the other eye

Prognosis

  • The prognosis is very good if diagnosis and treatment are prompt
  • The other unaffected eye has a 40-80% chance of developing acute angle closure glaucoma over the next 5-10 years

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