Acute angle-closure glaucoma

Glaucoma is a group of disorders characterised by optic neuropathy due, in the majority of patients, to raised intraocular pressure (IOP). It is now recognised that a minority of patients with raised IOP do not have glaucoma and vice versa.

In acute angle-closure glaucoma (AACG) there is a rise in IOP secondary to an impairment of aqueous outflow. Factors predisposing to AACG include:

hypermetropia (long-sightedness)
pupillary dilatation
lens growth associated with age

Features

severe pain: may be ocular or headache
decreased visual acuity
symptoms worse with mydriasis (e.g. watching TV in a dark room)
hard, red-eye
haloes around lights
semi-dilated non-reacting pupil
corneal oedema results in dull or hazy cornea
systemic upset may be seen, such as nausea and vomiting and even abdominal pain

Acute angle closure glaucoma of the right eye - note the semi-dilated pupil and erythema

Photograph showing acute angle-closure glaucoma

Investigations

tonometry to assess for elevated IOP
gonioscopy (literally looking, oscopy, at the angle, gonio): a special lens for the slit lamp that allows visualisation of the angle

Management

The management of AACG is an emergency and should prompt urgent referral to an ophthalmologist. Emergency medical treatment is required to lower the IOP with more definitive surgical treatment given once the acute attack has settled.

There are no guidelines for the initial medical treatment emergency treatment. An example regime would be:

combination of eye drops, for example:
- a direct parasympathomimetic (e.g. pilocarpine, causes contraction of the ciliary muscle → opening the trabecular meshwork → increased outflow of the aqueous humour)
- a beta-blocker (e.g. timolol, decreases aqueous humour production)
- an alpha-2 agonist (e.g. apraclonidine, dual mechanism, decreasing aqueous humour production and increasing uveoscleral outflow)
intravenous acetazolamide
- reduces aqueous secretions
some guidelines also recommend the use of topical steroids to reduce inflammation

Definitive management

laser peripheral iridotomy
- creates a tiny hole in the peripheral iris → aqueous humour flowing to the angle

+PassMedicine Notes

In acute angle-closure glaucoma (AACG) there is a rise in IOP secondary to an impairment of aqueous outflow. Factors predisposing to AACG include:

hypermetropia (long-sightedness)
pupillary dilatation
lens growth associated with age

Features

severe pain: may be ocular or headache
decreased visual acuity
symptoms worse with mydriasis (e.g. watching TV in a dark room)
hard, red-eye
haloes around lights
semi-dilated non-reacting pupil
corneal oedema results in dull or hazy cornea
systemic upset may be seen, such as nausea and vomiting and even abdominal pain

Investigations

tonometry to assess for elevated IOP
gonioscopy (literally looking, oscopy, at the angle, gonio): a special lens for the slit lamp that allows visualisation of the angle

Management

There are no guidelines for the initial medical treatment emergency treatment. An example regime would be:

combination of eye drops, for example:

a direct parasympathomimetic (e.g. pilocarpine, causes contraction of the ciliary muscle --> opening the trabecular meshwork --> increased outflow of the aqueous humour)
a beta-blocker (e.g. timolol, decreases aqueous humour production)
an alpha-2 agonist (e.g. apraclonidine, dual mechanism, decreasing aqueous humour production and increasing uveoscleral outflow)