Primary Angle Closure Glaucoma

Question 1

Aetiology

Answer 1

Narrowing or closure of anterior chamber due to pupil block mechanisms (when aqueous cannot flow between lens and posterior iris). Non-pupil block mechanisms such as plateau iris / lens-induced can cause angle closure too.

3 stages:
PACS - FIRST STAGE, reversible contact of the iris and TBM, no ONH damage, IOP normal, no anterior synechiae (adhesions of iris to angle)

PAC - SECOND STAGE - IOP is raised and AS is present.

PACG - FINAL STAGE - glaucomatous optic neuropathy has developed.

Acute angle closure - acute closure of AC causing spike in IOP along with pain, haloes around lights, vomiting, blurred vision

Question 2

Predisposing factors

Answer 2

Age - lens thickness increases, causing shallow AC
Shallow AC + short axial length - hypermetropia
Females
East asians
FHx

Drugs - mydriatics, anticholinergics (SSRI, tricyclic antidepressants), adrenergic agents (phenylephrine), topiramate (ciliary body oedema)

Surgery induced - may occur after vitreo retinal surgery with gas

Question 3

Symptoms

Answer 3

Usually none
Chronic PACG in more advance cases may have ocular/periocular pain with headaches.

AAC:
- Severe pain
- Redness
- Blurred vision
- Sickness and vomiting
- Haloes around lights

May have had intermittent attacks in the past e.g. short episodes of blurred vision with haloes around lights, eye pain and headaches

Question 4

Signs

Answer 4

Gonioscopy confirms ITC contact but VH and anterior segment OCT are still useful

PACS - eye looks normal but AC is narrow
PAC - IOP elevated and AS present
PACG - glaucomatous optic neuropathy

AAC
- Red eye - dilated conjunctival and limbal blood vessels causing ciliary flush
- Shallow AC with VH, cells and flare.
- High IOP (40-80mmHg)
- Corneal oedema
- Glaukomflecken - white grey lenticular opacities which is indicative of previous attacks
- Reduced vision
- Optic disc oedema and hyperaemia
- Pupil is fixed, semi-dilated, vertically ellipitcal

Question 5

Non-pharmacological management

Answer 5

PACS - Assess for risk factors for referral - otherwise no referral required. If the Px has PACS and:
- only one good eye
- vulnerable and unable to tell if any change in vision
- unable to access emergency eye care quickly as living in remote location
- high hypermetropia
- family history
- diabetes, or requiring regular pupil dilation
- antidepressant or anticholinergic drug use
… then refer these patients routinely.

IF not referring, review patients yearly.

PAC / PACG - urgent within 1 week, LPI or lens extraction can be performed. Pharmacological therapies to keep IOP low.

Question 6

Pharmacological management

Answer 6

For AAC:

Prior to referral, give pilocarpine (do not give if ciliary body oedema, lens-induced, non-pupil block mechanism)

Anti sickness and pain relief.
If Px is not vomiting, give single dose of Acetazolamide 500mg of Diamox (dangerous for those with kidney failure, contraindicated for sulphonamide allergy or sickle cell trait).

Refer as emergency - advise to take carer/friend with them

Question 7

Management at hospital?

Answer 7

AAC - aimed at breaking pupil block and reducing IOP
- Systemic treatment such as ACETAZOLAMIDE
- Hypotensive such as TIMOLOL, DORZOLAMIDE, BRINZOLAMIDE, BRIMONIDINE

Urgent - LPI but if corneal oedema present, then argon laser peripheral iridoplasty. Laser ablation cyclodiode where they have failed to respond to other treatments

Non-urgent - lens extraction.

PAC/PACG - LPI, topical hypotensives, lens extraction