DIS - Angle Closure Glaucoma II - Week 5

Question 1

List three mechanisms of angle closure.

Answer 1

Plateau iris
Pupil block
Posterior pressure

Question 2

Describe plateau iris. What happens on dilation? Give the clinical definition of plateau iris.

Answer 2

Caused by the anterior insertion of the iris into the ciliary body
Produces iris bunching in the angle on dilation
Closed angle on gonioscopy/OCT with a flat iris and normal AC depth

Question 3

What technique often fails with plateau iris?

Answer 3

Peripheral laser iridotomy

Question 4

Where does the ciliary body extend to in plateau iris and what does it support? What does it result in when indenting on gonioscopy?

Answer 4

The ciliary body extends under the iris, supports the far peripheral iris to give a double hump on indentation

Question 5

Describe the mechanism of AC crowding and how it differs to plateau iris. Describe what the choroid does.

Answer 5

Similar to plateau iris but the iris root is in a normal position
The cause of crowding is a ciliary body twist, rotating the iris about its scleral anchor
It twists further as the choroid pushes it further

Question 6

What is a major cause of angle closure in asian eyes?

Answer 6

AC crowding

Question 7

List a cause of AC crowding (not the mechanism).

Answer 7

Choroidal effusion causes the uvea to elongate anf the ciliary body to rotate forward with the scleral spur as the hinge
New location of the ciliary body is under the iris root

Question 8

Is choroidal effusion common in asian eyes with angle closure glaucoma or is it rare?

Answer 8

Common

Question 9

Describe pupil touch, why it happens (2), and its effect on IOP, if any. Note if this is normal or abnormal. Also note what happens in most cases.

Answer 9

Occurs whn the iris and lens make contact at the pupil margin
Happens due to lens growth with age, or due to forward lens placement (lens vault)
Pupil touch elevates IOP in the posterior chamber - normal ageing process
In most cases, increased posterior IOP will lift the iris off to re-establish flow under the iris

Question 10

Describe pupil block and what it is due to (2).

Answer 10

Requires iris touch and occurs due to muscle forces and age related loss of iris tissue tone

Question 11

Describe quigleys mechanism for how pupil block occurs (4). Explain what happens with miosis/mydriasis and if there is any angle block.

Answer 11

Iris muscles were slackest in mid dilation, when both iris muscles are fully relaxed
This gives greatest sphincter vector force onto the lens to block aqueous
Slack iris tissue would be more likely to form a forward bow
The dilator would pull this slack tissue into the angle, obstructing the TM
Miosis - sphincter tension keeps iris tight - no block
Mydriasis - dilator keeps iris tight - no block
Mid-dilation - block

Question 12

Describe what is meant by asian paradox for angle closure.

Answer 12

Asian eyes have similar anterior chamber depth to everyone else, but still get more primary angle closure than everyone else

Question 13

Do both pupil block and AC crowding collectively explain the asian paradox?

Answer 13

Yes

Question 14

Describe the corneal wedge for gonioscopy, including what you look for and setup.

Answer 14

Wedge defines the corneal limbus and the start of the angle
Offset the slit 30-45 and use a narrow beam
Look for reflections in the corneal epithelium and endothelium
Where they meet is schwalbes line

Question 15

What can you do when PTM is not visible on gonioscopy?

Answer 15

Indentation

Question 16

True or false

Angles open to PTM will not close

Answer 16

True

Question 17

Describe the management for a primary angle closure suspect including documentation/testing (5), review, and any referrals.

Answer 17

Educate the patient on self-monitoring as well as signs/symptoms of closure
Document:
Gonioscopy
IOP
AC depth
OCT (anterior and posterior)
VF yearly
Refer high risk cases

Question 18

Describe the management for a primary angle closure patient including documentation/testing (5), review (2), and any referrals.

Answer 18

A suspect with ischaemic iris changes
Refer for prophylactic peripheral laser iridotomy in both eyes
-review annually after surgery
Educate as with suspects

Document:
Gonioscopy
IOP
AC depth
OCT (anterior and posterior)
VF yearly

Annual review, 6/12 for high risk

Question 19

What do primary angle closure patients often develop after peripheral laser iridotomy?

Answer 19

Synaechiae - 25%

Question 20

Describe the management for a primary angle closure patient including documentation/testing (5), review, and any referrals.

Answer 20

Manage IOP as needed with meds and refer for surgery in both eyes

Document:
Gonioscopy
IOP
AC depth
OCT (anterior and posterior)
VF yearly

Review 6/12

Question 21

What is a very effective means of reducing IOP in patients with primary angle closure and primary angle closure glaucoma?

Answer 21

Lens extraction

Question 22

Is acute angle closure glaucoma an ocular emergency?

Answer 22

Yes, must be treated immediately

Question 23

Define acute angle closure glaucoma.

Answer 23

An aute and total outflow shutdown subsequent to long term angle compromise by the iris

Question 24

What must a patient have in order to diagnose acute angle closure glaucoma (2)?

Answer 24

Must have high IOP (>24mmHg)

Must have 4+ signs/symptoms for a presumptive diagnosis (2+ signs, 2+ symptoms)

Question 25

List three signs of acute angle closure glaucoma.

Answer 25

Pain
Nausea/vomiting
Blurry visiond

Question 26

List four signs of acute angle closure glaucoma.

Answer 26

Red eye
Corneal oedema or its symptoms
Pupil mid-dilated and unreactive
Shallow anterior chamber (vHSS/ST)

Question 27

Describe the OBA protocol for managing acute angle closure glaucoma. Is this a cure for the angle closure (5)? Explain. Include oral medications (2), noting what should be done if it takes a long time to get to hospital.

Answer 27

Instill the following 2 minutes apart:
1 drop beta blocker (timolol)
1 drop alpha agonist (alphagan)
1 drop carbonic anhydrase inhibitor (trusopt)
-the above is first aid, not a cure
1 drop pilocarpine 2%
Add 1 drop steroid if eye is inflamed
Oral diamox 2x250mg and 500mg K+
-if >1h to hospital, get diamox from pharmacy
-otherwise IV diamox by emergency doctor
Acute angle closure glaucoma requires urgent referral for surgery

Question 28

When managing acute angle closure glaucoma according to protocol, when should you not use pilocarpine?

Answer 28

If it is a retrolental cause (phakic/pseudophakic)

Question 29

What is the definitive treatment for primary angle closure glaucoma? Is it done in both eyes? Explain.

Answer 29

Surgery for both eyes, except in malignant glaucoma

Question 30

List three surgeries for primary angle closure glaucoma. Note which is old fastioned. Explain each briefly.

Answer 30

Peripheral laser iridotomy
-laser hole at the limbal margin
Iridoplasty
-laser of iris surface to tighten/reshape iris
Iridectomy (old fashioned)
-surgical triangle cut out of the iris
-rremoves TM, creates direct flow to scleral spur

Question 31

Does peripheral laser iridotomy prevent peripherla anterior synaechiae?

Answer 31

No, it is not prevented in 30% of patients

Question 32

Define malignant glaucoma and when it may occur.

Answer 32

When retrolental pressure pushes the lens forward and blocks the angle
May occur as a complication after eye surgery/CRVO/cataract/panretinal photocoagulation

Question 33

How is malignant glaucoma managed?

Answer 33

Aqueous suppressants as with angle closure glaucoma (diamox PO)

Question 34

What can be used to facilitate flow in malignant glaucoma?

Answer 34

Aggressive mydriasis (atropine)
Do not use pilocarpine

Question 35

Can pilocarpine be used to treat malignant glaucoma?

Answer 35

No, do not use pilocarpine on malignant glaucoma

Question 36

What are two mechanisms of malignant glaucoma?

Answer 36

Rapid and gross choroidal effusion in response to surgery or

Vitreous movement due to misdirected aqueous