GLAUCOMA 4 - VF Progression and Newer techniques Flashcards
(40 cards)
what is the main goal of management in glauc px?
lowering IOP
list 3 basic ways of controlling glaucoma?
DROPS, LASER OR SURGERY- imp to consider in vf progression but also when making clinical trials - eg SLT treatment at moorfields
what are some clinical methods to monitor glauc?
-clinical management- px worsening? px stable?
-clinical trials
-benchmark has to be function
what is one limitation of using vf progression as a way to quanitfy glauc?
very difficult to detect changes
how can we improve visual field testing?
- explain to px- as results can be confusing
- supervise
- environment-quiet+noise free
what is ‘noise’ in relation to vf plots?
things that can interfere with the vf plot results
list 6 examples of ‘noise’ (variability)?
- Pupil size
- Refractive error, cataract
- Response reliability
- Poor fixation
- Learning effects
- Fatigue effects
is there a gold std method to check for glauc progression?
nope
why is it difficult to detect change?
Slow process
No natural history-ethically- control needed but that means some ppl wont get tx
typical methods of assessing glauc px?
- optic nerve head
- oct
- iops
- field plots
disadv of vf tests to assess glauc progression? 4 points
- Difficult to do
- Subjective
- Not quantitative
- Based off experience and judgement
what did a study done looking at 5 glauc specialists observing the same vf plots? (interobserver)
not 100% agreed with one other- poor interobserver reliability
what are global indices on a vf plot?
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)
what does a mean defect of zero mean?
-means defect normal for age- it is when its negative that the vf is abnormal or worse
disadv of global indices?
- 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
what does ‘data reduction mean’?
reducing all data down into numbers
what does data reduction lead to?
loss of spatial information
i.e. we don’t know WHERE the VF defect is, just that there is one somewhere
why might be any reason MD gets worse (besides glauc)?
increase in media opacities- eg cataract
what is a newer way to measure mean defect at central location
visual field index
what is a pointwise or point by point method?- detailed diag in lecture
- ANALYSIS done at each location of central field
- looking at change over time
- sensitive tests ideal for a clinical trial-picking up small changes
what type of software is ‘point by point’ used in?
GPA- Glauc progression analysis
on a GPA, what does a dot indicate?
no change from baseline
on a GPA, what does an open triangle indicate?
significant change
on a GPA what does a black triangle indicate?
Change confirmed
- it is a “true change” therefore suspicious
- fallen below baseline on three occasions
