Visual Fields Flashcards
what are the two types of perimetry?
-kinetic
-static
what are the two types of kinetic perimetry?
-Goldmann
-Octopus
-gross (simple version)
what is recorded as the threshold in kinetic perimetry?
the specific location where the stimulus is just seen
what is kinetic perimetry?
perimetry where the size and luminance of the target can be varied
what do the rings and lines on a kinetic perimetry diagram show?
rings show extent of the visual field
lines are what the px reports they can actually see
why do you need to make sure the stimulus brightness in kinetic perimetry is just right?
because a big bright target could mean px subtle defects are missed and targets too small/ dim just wont be picked up regardless of wether the px has a defect
what are the advantages of kinetic perimetry?
-not confined to testing algorithms
-useful for patients with motility issues
why would you choose static over kinetic perimetry?
-as you need an experienced practitioner to do kinetic compared to static where it can be delegated
-you can see moving targets in the periphery better than stationary targets in the periphery
-it is reaction time dependent
what is static perimetry?
perimetry where light stimuli are presented at fixed locations
what are the two types of static perimetry
-suprathreshold
-threshold
what does C40 on suprathreshold perimetry mean?
central and 40 is the number of points presented to the patient
how is the brightness of the light of stimulus used in suprathreshold perimetry decided?
its 8dB brighter than the lowest amount of brightness the px is expected to see for their age
in suprathreshold, how does the brightness of the stimulus change?
as the stimulus moves into the periphery, the dimmer it gets
what are the advantages to suprathreshold?
-good for screening
-quick
-patients are expected to have normal visual fields
-good for patients at risk of a gross field defect
what are the disadvantages of suprathreshold perimetry>?
-miss subtle defects
-not useful in glaucoma suspects
-inconclusive defects on suprathreshold tests
what are the two types of suprathreshold perimetry?
c40 and ff81
what is the main difference between c40 and ff81 types of suprathreshold perimetry?
Main difference is c40 covers 30 degrees either side of fixation whereas ff81 covers 60 degrees either side so a larger field of visual fixation. C40 really should only be used for suspected macular problems or for a quick screening test
what is standard colour and size for static perimetry?
standard colour white
standard size 3
what is the threshold of the stimulus in threshold perimetry?
the minimum amount of light that gives a 50% detection probability
when may you make the size of stimulus bigger in threshold perimetry?
if the patient has poorer vision
what algorithm is most commonly used in threshold perimetry and why?
Full Threshold algorithm as its the gold standard by being the most accurate algorithm using a 4-2db staircase method
for threshold perimetry, what test pattern is used as standard? what test pattern is good for macula testing?
-central 24-2 = good for glaucoma, general and neurological pathologies
-central 10-2
what is esterman?
a suprathreshold test that the patient does binocularly
how do you use visual fields on a patient to test if they are fit to drive under DVLA?
-do Esterman
-make sure there is no rim artefacts if they wear their glasses
-they are allowed three attempts in their visit
-send it to DVLA if 3 attempts later and still not up to driving standards
-you can’s discuss with the px their test results