DIS - Glaucoma Detection Tutorial - Week 3 Flashcards
Does glaucoma commonly lead to blindness?
No, rarely
Describe the following stages of glaucoma therapy:
Detection
Assessment
Treatment (3)
Monitoring
Detection
-normal vs glaucoma suspect
Assessment
-glaucoma suspect vs glaucoma patient
Treatment
-severity grading
-setting target IOP
-drug selection and surgery referral
Monitoring
-stability vs progression
Is glaucoma an acquired disease?
Yes with rare exceptions
Is glaucoma generally symptomatic? Describe (2).
Except for acute angle closure glaucoma, the vast majority of glaucoma is asymptomatic
Do screenings detect glaucoma? Explain the role of an optometrist.
No, only routine eye exams do
Only optometrists perform routine eye exams
Can routine eye exams detect glaucoma? Explain the requirement.
Routine eye exams cannot detect glaucoma, only glaucoma suspects
Glaucoma evaluation/assessment is required to diagnose glaucoma
What is the lifetime risk of glaucoma in first degree relatives of those with glaucoma vs without family history?
22% compared to 2.3% without
What percentage of glaucoma is thought to be undiagnosed?
50%
Consider family ocular history. What are two ways to gauge the presence of glaucoma in this component?
Asking patients about their family ocular history
-very unreliable
Examining the 1st degree relatives of existing glaucoma patients
-much more beneficial
Is diabetes a factor for or against glaucoma? What is the current thought overall?
It is a controversial risk factor
-some studies show greater risk
-some show it is protective against glaucoma
-one showed no association at all
DM is thought to be a mild factor for glaucoma
Between hypertension and hypotension, which is a risk factor for glaucoma? Explain (3).
Both are:
Higher systolic BP
-drives more blood to the eye
-raises IOP, causing atherosclerosis
Low systolic BP
-reduces blood flow and oxygen to the eye
What IOP is thought to indicate strong steroid IOP response?
> 10-15mmHg
What percentage of the normal population has a strong steroid IOP response? What about the glaucoma population?
Normal - 5%
Glaucoma - 95%
Is IOP steroid response a strong or weak predictor of glaucoma?
Strong predictor
What two risks associated with glaucoma can antidepressants (note which) and anticholinergic drugs have?
SSRI
Increased risk of narrow angle glaucoma
Mild pipillary dilation and pupil block
What risk associated with glaucoma can topirimate?
Angle closure due to ciliary body swelling
Describe the type of glaucoma (or risk factor for glaucoma) the following races are a risk factor for:
Asian
African
Caucasian (2)
Asian - narrow angle glaucoma
African - early onset primary open angle glaucoma
Caucasian - pseudoexfoliation, pigment dispersion
Describe the type of glaucoma (or risk factor for glaucoma) the following refractive errors are a risk factor for:
Myopia (2)
Hyperopia
Myopia - pigment dispersion, primary open angle glaucoma
Hyperopia - narrow angle glaucoma
Describe the type of glaucoma (or risk factor for glaucoma) the following genders are a risk factor for:
Male (3)
Female (2)
Male - primary open angle glaucoma, ocular hypertension, traumatic glaucoma
Female - normal tension glaucoma, narrow angle glaucoma
Keeping the risk factors posed by certain demographics in mind, do demographics without clinical signs make a glaucoma suspect (2)? Explain with an example.
Demographics without clinical signs do not make a glaucoma suspect
Particular combinations should make you search more carefully
-caucasian, male, myope (pigment dispersion)
True or false
Glaucoma can occur at any IOP
True
Is there a significant IOP overlap between normal and glaucoma populations? Explain.
Yes
Except for IOP >32, both have the same shaped distribution
Compare mean IOP in glaucoma patients who progress compared to those who are stable.
They are almost identical
Can progressive glaucoma occur at normal/low IOP?
Yes
What does elevated IOP detect? Relate to glaucoma suspects. Keeping this in mind, what is the real clinical value of IOP?
Only detects ocular hypertension, not glaucoma
The real clinical value of IOP is to advise the practitioner the pressure at which glaucomatous damage occurred and can be used to set target IOP
What is the safe C/D ratio where you can’t have glaucoma? Explain (2).
You can have glaucoma at any C/D ratio, including 0
C/D ratios of 0.8 can be physiologic/healthy
Describe the Five R strategy for assessing the optic nerve. Describe each component.
Ring
-disc size, C/D out of proportion to disc size, tilt/rotation
Rim
-vertical C/D ratio, C/D asymmetry, ISNT rule, notching, pallor
Retinal vessels
-disc haemorrhages, vessel beyoneting, vessel baring
Regions of PPA
-beta peripapillary atrophy
RNFL
-B/D/B pattern, wedge defects
Is the number of retinal ganglion cells tied to globe size? Explain.
All eyes have around 1.5m RGCs, regardless of globe size
What determines disc size?
Scleral foramen
What is the spacing like of axons leaving via a small scleral opening, and how does this affect cupping? What about larger openings? What does this tell us about C/D ratios and optic nerve size?
Axons leaving via a small scleral opening will be more crowded
-no ONH cupping
Axons leaving via a larger scleral opening have more space
-larger ONH cupping
Therefore, C/D ratio intrinsically linked to optic nerve size
Does C/D ratio have clinical value without disc size? Explain in terms of disc sizes (30.
Its meaningless
-small discs should have almost no cup
-regular discs should have regular cups
-large discs should have large cups
Are glaucomatous changes easy to detect on small discs (4)?
Difficult to detect
-moderate axonal loss occurs without cupping
-dramatic axon loss with mild cupping
-visual field loss out of proportion to C/D ratio
What tends to happen to patients with large and small discs in terms of glaucoma suspicion?
Large discs with large cups tend to be unnecessarily over-investigated as glaucoma suspects
Small discs with small cups tend to be under-investigated
When using slit beam height to match vertical disc diameter using a 90D fundus lens, how should the lens minification effect be taken into account?
x1.3 for 90D
Describe how disc size can be estimated with an ophthalmoscope.
Using the medium aperture, a small disc will fit into the light spot
A regular disc will match the light spot
A large disc will be larger than the light spot
What anterior chamber angle (VH) should cause suspicion?
<0.3
In what five populations is there increased prevalence of narrow VH angles?
Hyperopia
Older age (thicker lens)
Asian race
Females
Anticholinergic drugs
Describe what pseudoexfoliation is, how it forms, and where it deposits.
White fibrillar deposit in anterior eye
PXF on lens capsule rubbed off by pupil motion
Fibres deposit in trabecular meshwork and impair outflow
What does pseudoexfolation also damage and what is a consequence of this?
PXF also damages lens zonules
-lens moves anteriorly
-secondary narrow angle glaucoma
What percentage of PXF patients go on to develop PXF glaucoma?
30-50%
What is the most common secondary cause of primary open angle glaucoma?
Pseudoexfolation
What age and gender demographic does pigment dispersion tend to affect? What is the onset?
Predominantly younger male myopes onset age 30-40 years old
What is the anterior chamber like in pigment dispersion syndrome, what happens to the iris, and what is a consequence of this?
Very deep anterior chamber and backward bowing iris
Lens zonules rub pigment off posterior iris
Considering that glaucoma is very easy to miss, what is one strategy you could use with every full eye exam?
Assume every patient has glaucoma at each exam
At the end of the consult, consciously exclude glaucoma
If you cant with certainty, then they are a glaucoma suspect
