DIS - Open Angle Glaucoma I - Week 3

Question 1

What is the prevalence of glaucoma in Australia? What about elsewhere?

Answer 1

Australia - 1.7-2.4%
Elsewhere - 2.5%

Question 2

Is glaucoma race or age dependent?

Answer 2

Yes to both

Question 3

What percentage of all blindness is due to glaucoma?

Answer 3

14%

Question 4

What was the old definition of glaucoma using IOP? Why is this no longer the definition and what is this called now in place of glaucoma?

Answer 4

Used to be IOP > 21mmHg, but many cases of glaucoma never have IOP >21 (LTG)
Now is called ocular hypertension (OHT)

Question 5

Is both an IOP of 21mmHg and CDR >0.5 a risk factor for open angle glaucoma?

Answer 5

Yes

Question 6

Is progression of glaucoma evident at the first visit? What does this mean for diagnosis and what four factors is this based on?

Answer 6

Progression isnt evident at first visit
Open angle glaucoma is often a presumptive diagnosis based on:
-risk factors
-appearance of the RNFL
-appearance of the NNR of the ON
-typical VF loss

Question 7

What defines the management of glaucoma?

Answer 7

The level of risk for glaucoma

Question 8

What six things are investigated to diagnose glaucoma?

Answer 8

IOP
Angle
Anterior chmaber
RNFL
ONH (NRR)
Visual field

Question 9

What is the outcome if there is an absence of all signs?

Answer 9

The patient is a glaucoma suspect (low-high risk)

Question 10

Define a diagnostic risk factor vs prognostic.

Answer 10

Diagnostic - attributes present in greater frequency in a disease
Prognostic - attributes that predict faster change once the disease is diagnosed

Question 11

What 5 eye conditions are considered high risk for glaucoma?

Answer 11

Myopia
Retinal vein occlusion
Eye injury
Iris degeneration
Papilloedema

Question 12

Which gender is at a lower risk of glaucoma?

Answer 12

Female

Question 13

Is diabetes considered a high risk for glaucoma? What about migraines and sleep apnoea?

Answer 13

All are low risk

Question 14

What defines ocular hypertension?

Answer 14

In a normal population, IOP gives a bell shaped curve, therefore ocular hypertension is a statistical concept, the cutoff of which is based on this normal distribution

Question 15

What is the average IOP including standard deviation? What IOP range would 95% of the population fall within?

Answer 15

15.6 ± 2.5 mmHg
95% is within 10-21mmHg

Question 16

Consider individuals with IOP above 21mmHg. Is this normal? What is this called? Explain (3).

Answer 16

Most people above 21mmHg are normal
ONH, RNFL and VF are normal
Called ocular hypertension

Question 17

What percentage of Australians have ocular hypertension?

Answer 17

3%

Question 18

Can open angle glaucoma be IOP independent? Explain (2).

Answer 18

Open angle glaucoma can be IOP independent below 18mmHg - low tension glaucoma

Question 19

Is high IOP a risk factor for glaucoma? Explain.

Answer 19

Above 18mmHg prevalence of glaucoma increases, so it is a risk factor

Question 20

What are IOP spikes a good indicator of?

Answer 20

Progression

Question 21

What is needed in all low tension glaucoma cases and for what purpose?

Answer 21

Need diurnal curve in all low tension glaucoma cases to dismiss spikes

Question 22

What thickness cornea is a higher risk for open angle glaucoma?

Answer 22

Thin cornea

Question 23

With tonometry, do thicc corneas tend to return higher or lower IOPs?

Answer 23

Higher

Question 24

If there are repeated measurements of IOP > 29mmHg, what must be done (2)?

Answer 24

Angle evaluated for closure (gonioscopy or OCT - or both)
CCT measured

Question 25

If there are repeated measurements of IOP < 5mmHg, what should be considered (2)?

Answer 25

Hypotony CCT measurement

Question 26

What aspect of high blood pressure can mean it is a risk for glaucoma?

Answer 26

Aggressive BP lowering

Question 27

Is steroid use a risk factor for glaucoma?

Answer 27

Yes

Question 28

What race is a risk factor for open angle glaucoma?

Answer 28

African-American

Question 29

What race is a risk factor for low tension glaucoma?

Answer 29

Japanese

Question 30

Above what age is a risk factor for low tension glaucoma?

Answer 30

>65 years old

Question 31

What is essential to diagnose primary angle closure glaucoma?

Answer 31

Gonioscopy

Question 32

For an angle to be considered open, on gonioscopy what structure must the angle be open to and over how many degrees? What else (3)?

Answer 32

Angle must be open to ATM for over 180° Angle must be unimpeded - no pigment, blood, congenital malformation

Question 33

What disc features are generally evaluated for glaucoma (4)?

Answer 33

Papillary crescents NNR thickness Other signs like haemorrhage CD ratio

Question 34

Compare a cupped disc to a saucer disc in terms of disc size and defect.

Answer 34

Cup = large disc + surface defect - steep profile for the edge Saucer = small disc + deep defect - shallow profile/tenting

Question 35

Is it more difficult to see the NRR in a cupped or saucer disc?

Answer 35

Saucer

Question 36

If surface fibres are affected, what distance in the visual field is defected?

Answer 36

Surface fibres = proximal VF defect

Question 37

If deep fibres are affected, what distance in the visual field is defected?

Answer 37

Deep fibres = distal VF defect

Question 38

What is the CDR an indirect index of (2)?

Answer 38

NNR and RGC number

Question 39

What does the CDR vary with? How does this affect its reliability for neuropathy?

Answer 39

Size of the scleral opening So CDR is confounded by disc size -it is not a reliable index of neuropathy

Question 40

Does saucerisation alter CDR? Explain.

Answer 40

No, but makes the cup edge harder to see

Question 41

What is an abnormal CDR? Include asymmetry.

Answer 41

>0.7 Asymmetry of >0.2

Question 42

In what percentage of people does the ISNT rule follow? What about IST?

Answer 42

ISNT - 50% IST - 87%

Question 43

Is the ISNT rule a reliable for glaucoma diagnosis?

Answer 43

Yes

Question 44

Does the NRR show pallow in early open angle glaucoma?

Answer 44

Never shows pallor

Question 45

In a normal NRR, what section is paler?

Answer 45

T margin

Question 46

What part of the NRR gets wider?

Answer 46

Towards the poles

Question 47

Describe how ON size can be estimated with the following thecniques: Slit lamp Opthalmoscopy

Answer 47

Slit lamp - adjust the slit size to fit the vertical ON Ophthalmoscopy - compare vertical ON with medium aperture -small ON <0.75, large ON >1.25

Question 48

What percentage of the population have very large discs and what should be expected of the NRR, CDR, and ISNT rule?

Answer 48

Expect thin NNR everywhere CDR will be large (≥0.7) but will give IST in most cases

Question 49

With what NNR thickness profile (ISNT) should you do VF with macula (2)?

Answer 49

If T=S, I Or if thinner than expected

Question 50

Are small discs usually saucerised or cupped?

Answer 50

Saucer

Question 51

What should you look for in small discs (2)?

Answer 51

Look for PPA and RNFL (visible due to crowding)