Acute angle-closure

Cards (12)

  • Acute angle-closure glaucoma:
    • Acute rise in intraocular pressure
    • Narrowing of the anterior chamber angle or the eye (between the iris and cornea)
    • Causes optic nerve damage and sight loss
  • Pathophysiology:
    • Occurs in anatomically pre-disposed individuals with shorter eye lengths and shallower anterior chambers
    • Reduced drainage of aqueous humour due to anterior chamber angle narrowing
    • Mediated by a pupillary block contact between the iris and the lens when the iris is in a mid-dilated position
    • causes the peripheral iris to bow forward blocking the drainage angle, with subsequent rapid rise in IOP.
  • Risk factors for AACG include:
    • Increasing age: particularly 6th to 7th decade of life
    • Female sex: women have a three times greater risk than men
    • East Asian ethnicity
    • Family history
    • Anatomical predisposition: including short eyeball length and hypermetropia (longsightedness)
  • Pupil mid-dilation can cause AACG by precipitating pupillary block in those at risk
    • Being in a dark room
    • Anticholinergics e.g. oxybutynin
    • SSRIs and TCAs
    • Pupil dilating drops e.g. tropicamide - associated with bilateral AACG
  • History:
    • Symptoms tend to develop over hours to days
    • Since pupil mid-dilation can trigger AACG, the patient may have been in a dark room when symptoms began or be taking medications that cause pupil dilation
  • Typical symptoms of AACG include:
    • Unilateral severe eye pain or headache that may cause nausea and vomiting.
    • Profound reduction in visual acuity or visual loss
    • Rainbow coloured haloes around bright lights
  • Clinical exam:
    • Eye is red and hard - due to a rapid rise in IOP
    • Diffusely hazy cornea limiting view of the iris and pupil
    • A fixed, non-reactive, mid-dilated pupil
    • Very high IOP >30
  • High IOP can be confirmed by asking the patient to close their eye and gently palpating using the tips of both index fingers. An eye with very high IOP will feel ‘hard’ on palpation.
  • Investigations:
    • Gonioscopy - assessing the angle between the angle between the iris and cornea
    • Tonometry (Goldmann applanation) - measure IOP
  • Management to initiate before specialist assessment:
    • Oral analgesics
    • Anti-emetics
    • Patient can be laid flat - opens anterior chamber angle
  • Specialist acute management of AACG includes:
    • Systemic pressure-reducing agents: acetazolamide (Diuretic) (IV/oral)
    • Topical pressure-reducing agents (e.g. beta-blockers)
    • Topical steroids to reduce inflammation
    • Peripheral iridotomy (a laser hole through the iris) to allow a separate route for aqueous drainage other than through the pupil
  • Complications of AACG include:
    • Sight loss
    • Central or branch retinal vein occlusion
    • Repeated episodes of AACG