Acute glaucoma

Question 1

What is glaucoma?

Answer 1

group of disorders characterised by optic neuropathy due (in majority) to raised intraocular pressure (IOP)

Question 2

What is acute angle-closure glaucoma (AACG)?

Answer 2

rise in IOP secondary to impairment of adequous outflow

Question 3

What are 6 key factors predisposing to AACG?

Answer 3

1. Hypermetropia (long-sightedness)
2. Pupillary dilatation
3. Lens growth associated with age
4. Female
5. Asian
6. Use of certain medications e.g. antimuscarinics (amitriptyline)

Question 4

What are 8 presenting features of acute angle closure glaucoma?

Answer 4

1. Severe pain: ocular or headache
2. Decreased visual acuity
3. Nausea and vomiting (sometimes abdo pain)
4. Hard, red eye
5. Fixed, semi-dilated pupil
6. Haloes arond lights
7. Corneal oedema - dull or hazy cornea
8. Symptoms worse with mydriasis (e.g. watching TV in dark room, at evening)

Question 5

What referral is part of the immediate management of acute angle closure glaucoma?

Answer 5

urgent referral to ophthalmologist (it is an emergency)

Question 6

What is the approach to treatment of AACG?

Answer 6

• emergency - initial medical treatment to lower IOP
• More definitive surgical treatment once attack has settled

Question 7

What are 4 aspects of the medical management of AACG?

Answer 7

1. Direct parasympathomimetic eye drops e.g. pilocarpine
2. Topical beta-blocker eye drops e.g. timolol
3. Topical alpha 2 agonists e.g. brimonidine, apraclonidine
4. IV acetazolamide (carbonic anhydrase inhibitor)

Question 8

Of the treatment options available for medical lowering of IOP, what is the guidance for treatment of AACG?

Answer 8

no guidelines for initial emergency treatment so combination of eye drops + IV acetazolamide should be given

Question 9

What is the mechanism of action of direct parasympathomimectics such as pilocarpine to treat AACG?

Answer 9

• parasympathomimetic i.e. muscarinic agonist
• causes contraction of the ciliary muscle
• this opens the trabecular meshwork
• leads to increased outflow of aqueous humour

Question 10

What is the mechanism of action of beta blockers e.g. timolol to treat AACG?

Answer 10

reduce aqueous humour production

Question 11

What is the mechansim of action of alpha-2 agonists (e.g. apraclonidine, brimonidine) to treat AACG?

Answer 11

DUAL ACTION: increase uveoscleral outflow and decrease aqueous humour production

Question 12

What is the mechanism of action of IV acetazolamide to treat AACG?

Answer 12

carbonic anhydrase inhibitor

reduces aqueous secretions

Question 13

What are 2 examples of alpha-2 agonists used to treat AACG?

Answer 13

brimonidine, apraclonidine

Question 14

What is the acronym to remember the drugs used for medical management of AACG?

Answer 14

PABA: pilocarpine, alpha-2-agonists, beta blockers, acetazolamide

Question 15

What is the definitive management of AACG?

Answer 15

laser peripheral iridotomy

Question 16

What does laser peripheral iridotomy involve?

Answer 16

YAG (infrared, 1020nm) laser creates a tiny hole in the peripheral iris, allowing aqueous humour to flow to the angle

aqueous is secreted behind the iris but drains in front of it (drains in angle between cornea and iris)

Question 17

What are 4 possible findings on examination in AACG?

Answer 17

1. Red, hard eye
2. Cloudy cornea (due to corneal oedema)
3. Mid-dilated pupil
4. Reduced visual acuity

Question 18

What are 5 complications of AACG?

Answer 18

1. Temporary loss of vision
2. Malignant glaucoma
3. Iris sphincter atrophy
4. Permanently dilated pupil
5. Permanent blindness

Question 19

What is often performed alongside peripheral iridotomy in one eye for AACG?

Answer 19

prophylactic peripheral iridotomy in contralateral eye