GLAUCOMA 4 - VF Progression and Newer techniques

Question 1

what is the main goal of management in glauc px?

Answer 1

lowering IOP

Question 2

list 3 basic ways of controlling glaucoma?

Answer 2

DROPS, LASER OR SURGERY- imp to consider in vf progression but also when making clinical trials - eg SLT treatment at moorfields

Question 3

what are some clinical methods to monitor glauc?

Answer 3

-clinical management- px worsening? px stable?
-clinical trials
-benchmark has to be function

Question 4

what is one limitation of using vf progression as a way to quanitfy glauc?

Answer 4

very difficult to detect changes

Question 5

how can we improve visual field testing?

Answer 5

• explain to px- as results can be confusing
• supervise
• environment-quiet+noise free

Question 6

what is ‘noise’ in relation to vf plots?

Answer 6

things that can interfere with the vf plot results

Question 7

list 6 examples of ‘noise’ (variability)?

Answer 7

1. Pupil size
2. Refractive error, cataract
3. Response reliability
4. Poor fixation
5. Learning effects
6. Fatigue effects

Question 8

is there a gold std method to check for glauc progression?

Answer 8

nope

Question 9

why is it difficult to detect change?

Answer 9

Slow process
No natural history-ethically- control needed but that means some ppl wont get tx

Question 10

typical methods of assessing glauc px?

Answer 10

• optic nerve head
• oct
• iops
• field plots

Question 11

disadv of vf tests to assess glauc progression? 4 points

Answer 11

• Difficult to do
• Subjective
• Not quantitative
• Based off experience and judgement

Question 12

what did a study done looking at 5 glauc specialists observing the same vf plots? (interobserver)

Answer 12

not 100% agreed with one other- poor interobserver reliability

Question 13

what are global indices on a vf plot?

Answer 13

Mean Defect (MD)- zero means defect is normal for their age, the more negative the worst the VF is
Average of all deviations
Rate of loss (dB/year)

Question 14

what does a mean defect of zero mean?

Answer 14

-means defect normal for age- it is when its negative that the vf is abnormal or worse

Question 15

disadv of global indices?

Answer 15

• data reduction
  -Poor sensitivity - low number - small md number-might not be sensitive to that tiny change at one or two locations - which might be more important than depression visual field (eg MD: -5db can look different in diff vf plots) md can be stable- and px could still be losing imp vision

Question 16

what does ‘data reduction mean’?

Answer 16

reducing all data down into numbers

Question 17

what does data reduction lead to?

Answer 17

loss of spatial information
i.e. we don’t know WHERE the VF defect is, just that there is one somewhere

Question 18

why might be any reason MD gets worse (besides glauc)?

Answer 18

increase in media opacities- eg cataract

Question 19

what is a newer way to measure mean defect at central location

Answer 19

visual field index

Question 20

what is a pointwise or point by point method?- detailed diag in lecture

Answer 20

• ANALYSIS done at each location of central field
• looking at change over time
• sensitive tests ideal for a clinical trial-picking up small changes

Question 21

what type of software is ‘point by point’ used in?

Answer 21

GPA- Glauc progression analysis

Question 22

on a GPA, what does a dot indicate?

Answer 22

no change from baseline

Question 23

on a GPA, what does an open triangle indicate?

Answer 23

significant change

Question 24

on a GPA what does a black triangle indicate?

Answer 24

Change confirmed
- it is a “true change” therefore suspicious
- fallen below baseline on three occasions

Question 25

on a GPA what does half a black triangle indicate?

Answer 25

change will be confirmed at next visit

Question 26

how many VFs are needed to detect a ‘true change’?

Answer 26

5 VFs!
(baseline is avg of 2 VFs, + 3 follow up visits)

Question 27

on a gpa what does X indicate?

Answer 27

‘Too much’ variability
or defect at baseline
(no decision)

Question 28

how many black triangles do you need to be able to say there is likely progression?

Answer 28

3!

Question 29

roughly how long after baseline does it take to detect a VF change?

Answer 29

2 years (6 month recall and need 5 VFs for a true change to be detected)

Question 30

what is an advantages of GPA and where is it used?

Answer 30

very sensitive= used in clinical trials

Question 31

disadvantages of GPA?

Answer 31

• Dependent on Baseline
• Database?
• Does not use all the fields

Question 32

Why is it imp to have good software?

Answer 32

to help clinical decisions

Question 33

name some vf glaucoma software

Answer 33

• progressor(medisoft)
• new software- OPEN eyes
• GPA on Humphrey

Question 34

main things to consider when using vf software for glauc

Answer 34

Detecting progression to see if treatment works

Pointwise methods more sensitive

Good software available – Should be used!

Question 35

why is it important to create functional tests or have novel perimetry?

Answer 35

Optic nerve will already start damaging itself before symtpoms seen or signs noticed - so structural change before impact on visual function

Question 36

what axons are lost first in glauc and which pathway does this affect

Answer 36

Larger axons- first loss to glac- these larger axons belong to magnocellular pathway- can be probed by flickr, colour and emotion

Question 37

what does magnocellular pathway correspond to?

Answer 37

High amounts of flicker

Achromatic stimuli

Moving stimuli

Low spatial frequencies

Question 38

as glauc affects magnocellular pathway, what is a proposed method of novel perimetry + state some limitations?

Answer 38

-blue on yellow perimetry (SWAP)
-Longer Test! + Adaptation required
-More variability
-Poor response in elderly as yellowing of crystalline lens with age

Question 39

another novel proposed test?

Answer 39

frequency doubling test

Question 40

is frequency doubling test more effect at early detection of glauc?

Answer 40

No good evidence that the stimuli offers ‘earlier’ detection

But a well-designed instrument- so plus is it takes up less space