DIS - Angle Closure Glaucoma I - Week 5 Flashcards
Define primary angle closure.
Caused by narrow angles having intermittent periods of closure
What is sudden total angle closure called?
Acute angle closure glaucoma
Describe what is meant by a primary angle closure suspect. What should be done with these individuals (including review schedule)?
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
Describe what is meant by primary angle closure (clinically, not mechanisms). What is thought to be happening with the angle?
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
Do ischaemic iris changes need surgical intervention or does it make no difference?
Needs surgery
What percentage of primary angle closures convert to primary angle closure glaucoma in chinese people? Does this change with peripheral laser iridotomy?
25% converts to primary angle closure glaucoma despite peripheral laser iridotomy
Clinically, what is meant by primary angle closure glaucoma (6)?
Same criteria as with primary angle closure, with the addition of: High IOP RNFL loss or NRR loss or ON loss or VF loss
What is the presumptive diagnosis of acute angle closure glaucoma based on?
the presence of multiple signs and symptoms
List 6 features of ischaemic iris changes, including one for the lens (6 total).
Peripheral anterior synechiae Increased pigment in the PTM (G2+) High IOP (>24mmHg) Whorling (distortion of radial fibres) Iris atrophy Glaucomflecken
At what age range does risk for primary angle closure become significant?
50-70
Which gender is at a higher risk of rimary angle closure and by how much?
Females - 2x males, especially in younger populations
Does family history of primary angle closure increase individual risk?
Yes
Is there greater risk of acquiring primary angle closure in a fellow eye after getting it in one eye or is the risk independent?
Yes
What race is at a greater risk of primary angle closure?
Asians - especially east asians
List three ocular risk factors for primary angle closure.
Narrow angle
Shallow anterior chamber
Exfoliation
What race is at a higher risk of exfoliation?
Caucasian
What is a narrow anterior chamber opening on an OCT?
<11.7mm
What lens vault measurement on an OCT scan is a risk for primary angle closure?
≥0.60mm
What is considered a shallow anterior chamber depth?
<2.1mm
List two provocative tests for primary angle closure and an IOP measurement cutoff.
Dark room - IOP after 30 minutes in a dark room
Water drinking test - 1L in 5 minutes, IOP at 15m, 30m, 45m
IOP >24mmHg
What does a vHSS test consider?
Angle proximity to the iris
What does the shadow test estimate and what is it due to?
Estimates AC depth - shadow caused by iris bow
How is the shadow test expressed?
Limbus to pupil margin distance for shadow
Greater bowing indicates a more anterior iris
What constitutes a fail on the shadow test?
If more than 33% is shadow
Does the shadow test correlate well with anterior chamber depth?
Yes
List two anatomical risk factors for primary angle closure for the iris and note which of the shadow test and vHSS assesses which.
Risk -anterior chamber depth -proximity of TM to cornea Shadow test assesses depth vHSS assesses proximity
What single test identifies primary angle closure accurately?
None
What test is the most useful in isolation in regards to primary angle closure?
Shadow test
What two tests together identify high risk for primary angle closure best?
Shadow test and vHSS
Describe how to do smiths test for measuring the anterior chamber. Include the beam setup.
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
Describe the conversion factor for smiths test.
Multiply the length of the slit by 1.4 to get anterior chamber depth
Describe how to do a modified smiths test for screening. Include the beam setup.
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
What anterior chamber width is a risk factor for primary angle closure?
<11.7mm
Should gonioscopy/OCT scanning for assessing primary angle closure be done in a lit or dark room? Why?
Done in the dark because AC crowding is worst on dilation
What is the normal anterior chamber depth (give range for 98% of the population)?
2.1-3.8mm
Is there any difference in anterior chamber depth between races?
No
