Acute Angle Closure Glaucoma (AACG)

Diagnosis

Acute angle closure glaucoma develops when drainage of aqueous humour through the trabecular meshwork is blocked by folds of the iris occurring on dilation of the pupil. The intraocular pressure (normally up to 21 mmHg) rises acutely causing pressure related symptoms and signs.

AACG is more frequent in elderly hypermetropes (long sighted) due to a shallower anterior chamber and may be associated with recent changes in medication, particularly drugs with anticholinergic effects.

Patients often describe prodromal symptoms of haloes or rainbows around bright lights. These often occur in the evening when the pupil dilates, and ease on going to sleep. In the acute presentation however, systemic symptoms such as nausea, vomiting, headache and abdominal pain may predominate, confusing the unwary clinician [12].

On examination the eye is painful with reduced visual acuity, perilimbal conjunctival injection and a hazy cornea. The pupil is mid-dilated and unreactive to light.

Learning Bite

Acute angle closure glaucoma may cause significant systemic symptoms but a painful red eye, with reduced acuity and a fixed and mid-dilated pupil, are cardinal signs and need an emergency ophthalmic opinion.

Treatment

Treatment should be commenced e.g. opiate analgesia for pain, anti-emetic (if required) for nausea and IV acetylzolamide 500mg IV to reduce the intraocular pressure.

Treatment with a topical miotic, such as pilocarpine 1% or 2% every 5 minutes, should be started approximately 1 hour after commencing other measures as initially the pupil may be paralysed and unresponsive.