DIS - Angle Closure Glaucoma I - Week 5

Question 1

Define primary angle closure.

Answer 1

Caused by narrow angles having intermittent periods of closure

Question 2

What is sudden total angle closure called?

Answer 2

Acute angle closure glaucoma

Question 3

Describe what is meant by a primary angle closure suspect. What should be done with these individuals (including review schedule)?

Answer 3

PTM is not visible in 2 mirrors
Consider risk factors and work up for primary angle closure glaucoma
Review closely 6/12 if high risk

Question 4

Describe what is meant by primary angle closure (clinically, not mechanisms). What is thought to be happening with the angle?

Answer 4

Same criteria as with a suspect - PTM not visible in 2 mirrors, with the addition of ischaemic iris changes
Thought the angle is slowly zipping up

Question 5

Do ischaemic iris changes need surgical intervention or does it make no difference?

Answer 5

Needs surgery

Question 6

What percentage of primary angle closures convert to primary angle closure glaucoma in chinese people? Does this change with peripheral laser iridotomy?

Answer 6

25% converts to primary angle closure glaucoma despite peripheral laser iridotomy

Question 7

Clinically, what is meant by primary angle closure glaucoma (6)?

Answer 7

Same criteria as with primary angle closure, with the addition of:
High IOP
RNFL loss or
NRR loss or
ON loss or
VF loss

Question 8

What is the presumptive diagnosis of acute angle closure glaucoma based on?

Answer 8

the presence of multiple signs and symptoms

Question 9

List 6 features of ischaemic iris changes, including one for the lens (6 total).

Answer 9

Peripheral anterior synechiae
Increased pigment in the PTM (G2+)
High IOP (>24mmHg)
Whorling (distortion of radial fibres)
Iris atrophy
Glaucomflecken

Question 10

At what age range does risk for primary angle closure become significant?

Answer 10

50-70

Question 11

Which gender is at a higher risk of rimary angle closure and by how much?

Answer 11

Females - 2x males, especially in younger populations

Question 12

Does family history of primary angle closure increase individual risk?

Answer 12

Yes

Question 13

Is there greater risk of acquiring primary angle closure in a fellow eye after getting it in one eye or is the risk independent?

Answer 13

Yes

Question 14

What race is at a greater risk of primary angle closure?

Answer 14

Asians - especially east asians

Question 15

List three ocular risk factors for primary angle closure.

Answer 15

Narrow angle
Shallow anterior chamber
Exfoliation

Question 16

What race is at a higher risk of exfoliation?

Answer 16

Caucasian

Question 17

What is a narrow anterior chamber opening on an OCT?

Answer 17

<11.7mm

Question 18

What lens vault measurement on an OCT scan is a risk for primary angle closure?

Answer 18

≥0.60mm

Question 19

What is considered a shallow anterior chamber depth?

Answer 19

<2.1mm

Question 20

List two provocative tests for primary angle closure and an IOP measurement cutoff.

Answer 20

Dark room - IOP after 30 minutes in a dark room
Water drinking test - 1L in 5 minutes, IOP at 15m, 30m, 45m
IOP >24mmHg

Question 21

What does a vHSS test consider?

Answer 21

Angle proximity to the iris

Question 22

What does the shadow test estimate and what is it due to?

Answer 22

Estimates AC depth - shadow caused by iris bow

Question 23

How is the shadow test expressed?

Answer 23

Limbus to pupil margin distance for shadow
Greater bowing indicates a more anterior iris

Question 24

What constitutes a fail on the shadow test?

Answer 24

If more than 33% is shadow

Question 25

Does the shadow test correlate well with anterior chamber depth?

Answer 25

Yes

Question 26

List two anatomical risk factors for primary angle closure for the iris and note which of the shadow test and vHSS assesses which.

Answer 26

Risk -anterior chamber depth -proximity of TM to cornea Shadow test assesses depth vHSS assesses proximity

Question 27

What single test identifies primary angle closure accurately?

Answer 27

None

Question 28

What test is the most useful in isolation in regards to primary angle closure?

Answer 28

Shadow test

Question 29

What two tests together identify high risk for primary angle closure best?

Answer 29

Shadow test and vHSS

Question 30

Describe how to do smiths test for measuring the anterior chamber. Include the beam setup.

Answer 30

Slit at 60 in the centre of the anterior chamber with a horizontal beam Focus on the corneal mire, lengthen the slit intil the lens mire (blurry mire) and cornea mire just touch

Question 31

Describe the conversion factor for smiths test.

Answer 31

Multiply the length of the slit by 1.4 to get anterior chamber depth

Question 32

Describe how to do a modified smiths test for screening. Include the beam setup.

Answer 32

Use a fixed 2mm slit or 2mm spot Slit at 60 at the centre of the anterior chamber If the two mires touch, it is a shallow anterior chamber

Question 33

What anterior chamber width is a risk factor for primary angle closure?

Answer 33

<11.7mm

Question 34

Should gonioscopy/OCT scanning for assessing primary angle closure be done in a lit or dark room? Why?

Answer 34

Done in the dark because AC crowding is worst on dilation

Question 35

What is the normal anterior chamber depth (give range for 98% of the population)?

Answer 35

2.1-3.8mm

Question 36

Is there any difference in anterior chamber depth between races?

Answer 36

No