acute angle glaucoma

Question 1

what is the pathophysiology of acute angle closure glaucoma?

Answer 1

iris bulges forward and seals off the trabecular meshwork from the anterior chamber preventing aqueous humour from being able to drain away.

This leads to a continual build-up of pressure in the eye. The pressure builds up particularly in the posterior chamber, which causes pressure behind the iris and worsens the closure of the angle.

Question 2

what are the risk factors for acute angle closure glaucoma?

Answer 2

increasing age
Females are affected around 4 times more often than males
Family history
Chinese and East Asian ethnic origin. Unlike open-angle glaucoma, it is rare in people of black ethnic origin.
Shallow anterior chamber

Question 3

which medications can precipitate acute angle closure glaucoma?

Answer 3

Adrenergic medications such as noradrenalin

Anticholinergic medications such as oxybutynin and solifenacin

Tricyclic antidepressants such as amitriptyline, which have anticholinergic effects

Question 4

how will someone with acute angle closure glaucoma present?

Answer 4

Severely painful red eye
Blurred vision
Halos around lights
Associated headache, nausea and vomiting

Question 5

how will the eye appear on examination?

Answer 5

Red-eye
Teary
Hazy cornea
Decreased visual acuity
Dilatation of the affected pupil
Fixed pupil size
Firm eyeball on palpation

Question 6

what is the initial management for an acute angle closure glaucoma?

Answer 6

• -it is potentially lie threatening, they need a same day review by an opthalmologist. call an ambulance if in GP
• lie patient flat without pillow
• give pilocarpine eye drops-
  2% for blue eyes and 4% for brown
• 500mg acetozolamide
• analgesia and anti emetic

Question 7

what is the mechanism of action of pilocarpine?

Answer 7

acts on the muscarinic receptors in the sphincter muscles in the iris and causes constriction of the pupil.

Therefore it is a miotic agent. It also causes ciliary muscle contraction.

These two effects cause the pathway for the flow of aqueous humour from the ciliary body, around the iris and into the trabecular meshwork to open up.

Question 8

what is the mechanism of action of acetozolamide?

Answer 8

a carbonic anhydrase inhibitor. This reduces the production of aqueous humour.

Question 9

what is the definitive management of an acute angle closure glaucoma?

Answer 9

Laser iridotomy is usually required as a definitive treatment.

This involves using a laser to make a hole in the iris to allow the aqueous humour to flow from the posterior chamber into the anterior chamber.