Visual Fields

Question 1

what are the two types of perimetry?

Answer 1

-kinetic
-static

Question 2

what are the two types of kinetic perimetry?

Answer 2

-Goldmann
-Octopus
-gross (simple version)

Question 3

what is recorded as the threshold in kinetic perimetry?

Answer 3

the specific location where the stimulus is just seen

Question 4

what is kinetic perimetry?

Answer 4

perimetry where the size and luminance of the target can be varied

Question 5

what do the rings and lines on a kinetic perimetry diagram show?

Answer 5

rings show extent of the visual field
lines are what the px reports they can actually see

Question 6

why do you need to make sure the stimulus brightness in kinetic perimetry is just right?

Answer 6

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

Question 7

what are the advantages of kinetic perimetry?

Answer 7

-not confined to testing algorithms
-useful for patients with motility issues

Question 8

why would you choose static over kinetic perimetry?

Answer 8

-as you need an experienced practitioner to do static compared to kinetic 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

Question 9

what is static perimetry?

Answer 9

perimetry where light stimuli are presented at fixed locations

Question 10

what are the two types of static perimetry

Answer 10

-suprathreshold
-threshold

Question 11

what does C40 on suprathreshold perimetry mean?

Answer 11

central and 40 is the number of points presented to the patient

Question 12

how is the brightness of the light of stimulus used in suprathreshold perimetry decided?

Answer 12

its 8dB brighter than the lowest amount of brightness the px is expected to see for their age

Question 13

in suprathreshold, how does the brightness of the stimulus change?

Answer 13

as the stimulus moves into the periphery, the dimmer it gets

Question 14

what are the advantages to suprathreshold?

Answer 14

-good for screening
-quick
-patients are expected to have normal visual fields
-good for patients at risk of a gross field defect

Question 15

what are the disadvantages of suprathreshold perimetry>?

Answer 15

-miss subtle defects
-not useful in glaucoma suspects
-inconclusive defects on suprathreshold tests

Question 16

what are the two types of suprathreshold perimetry?

Answer 16

c40 and ff81

Question 17

what is the main difference between c40 and ff81 types of suprathreshold perimetry?

Answer 17

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

Question 18

what is standard colour and size for static perimetry?

Answer 18

standard colour white
standard size 3

Question 19

what is the threshold of the stimulus in threshold perimetry?

Answer 19

the minimum amount of light that gives a 50% detection probability

Question 20

when may you make the size of stimulus bigger in threshold perimetry?

Answer 20

if the patient has poorer vision

Question 21

what algorithm is most commonly used in threshold perimetry and why?

Answer 21

Full Threshold algorithm as its the gold standard by being the most accurate algorithm using a 4-2db staircase method

Question 22

for threshold perimetry, what test pattern is used as standard? what test pattern is good for macula testing?

Answer 22

-central 24-2 = good for glaucoma, general and neurological pathologies
-central 10-2

Question 23

what is esterman?

Answer 23

a suprathreshold test that the patient does binocularly

Question 24

how do you use visual fields on a patient to test if they are fit to drive under DVLA?

Answer 24

-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

Question 25

on esterman what is the highest percentage of false positive score?

Answer 25

no more than 20%

Question 26

how does sita work?

Answer 26

uses a staircase method while constructing mathematical models of normal and abnormal visual behaviour by comparing the frequency of seeing curve of the normal eye to the patients eye

Question 27

what are the three types of sita? which is most common?

Answer 27

Most patients do sita fast but others are sita standard and sita faster but the longer the test goes on for, the more accurate the result so if you can do standard,

Question 28

how does sita reduce test time?

Answer 28

continuously updates the algorithm based on patient responses including altering stimuli presentation and speed based on reaction time

Question 29

What are the positives of threshold testing?

Answer 29

-detects subtle defects including early glaucoma
-gives us info on the depth (severity) of the defect
-better comparison of results to age matched normative data
-visual field is mapped with more precision
-can be used to closely monitor the progression of visual field loss in detail

Question 30

what are the minimum visual fields to meet driving standard?

Answer 30

-group 1: field of at least 120 degrees on the horizontal using a target equivalent to white Goldman iii4e. No significant defect in the binocular field within 20 degrees of fixation above or below the horizontal meridian
-group 2: horizontal visual field of at least 160 degrees, extension should be at least 70 degrees left and right and 30 degrees up and down . no defects should be present within central 30 degree radius