measurement of reduced function

Question 1

Snellen chart

Answer 1

1862
most common used- quick and easy
however its all of high contras
also spatial frequency- doesn’t correlate with real world situation
uneven crowding-
less chances of getting letters correct as only 1/60 letter- disheartening
not even used in research- not good for stats
notation is a bit dodgy too

Question 2

log mar chart

Answer 2

5 letters on each line
can be used at any D
spacing is equal to width and height of letters- .1log step
each letter is 0.02- score takes into account very letter read correctly.
task and crowding is same down the task
different viewing D taken into account
noted in log mar

Question 3

we also test near reading

Answer 3

not just va
but speed
ease
effect of lighting

Question 4

bailry-lovie near card

Answer 4

u can use log mar near card @25cm, if u use N u have to say at which D

High contrast

2,3,5 words per line

task variation down the chart

Size between n2-n80

unrelated words- no context- so can tell scotoma

Question 5

PNAC card-199

Answer 5

n5-n80
geometric progression like log mar
equal number ofwords- 3- one 3, one 4, one 5
related world sequences
basic vocal
no punctuation, lower case, times new roman
paragraph on back to assess reading speed and ease

Question 6

near vision testing

Answer 6

push them
if n- give wd
do mono and binocular withought local light
and binocular with local light

Question 7

acuity reserves

Answer 7

3:1/ 2:1
we expect them to read 160 letters per min this is for fluent reading

for spot reading u want them to read 40words per min and also an acuity reserve of 1:1

Question 8

contrast sensitivity testing

Answer 8

pelli-robinson chart
contrast threshold chard
16 triplets- on 8 lines
contrast reduces by 0.15log cs steps
externally illuminated of 85cd/m2
10AFC
1m working distance
recording at 3cycles per degree- the peak of a contrast sensitivity function
logarthimic reduction in contrast

Question 9

how would u score on the pelli-robinson chart

Answer 9

original- u score when 2/3 of the last triplet correct
in the elliot system- each letter is 0.05 and d=c=o so more reliable

as px goes lower down- wait for summation to get threshold

record as a percentage

Question 10

whats the contrast reserve

Answer 10

10:1 for fluent
for spot 3:1

contrast reserve

Question 11

Whittaker categories (values relate to contrast threshold percentages)

Answer 11

90% to 31% severe loss, consider non- optical devices
– 22% to 7.8% significant loss, requires contrast enhancement
– 5.6% to 1.9% noticeable loss, requires lighting evaluation
– 1.4% to 0.5% nor mal to near normal

Question 12

Amsler chart

Answer 12

central 20 degrees of vf- 20 H and 20 V lines
30cm wd
white lines on black background
gross and subjective
monocular
well illuminated- fixate

Question 13

henson screener

Answer 13

large cross in centre
more so central vf loss
limited ino on peripheral loss- get henson pro

Question 14

humphrey

Answer 14

larger diagonal cross for better fixation- information on central and peripheral loss
estermann- very supra-threshold- dvl a

Question 15

goldman

Answer 15

more so useful for periphery
largest brightest targets to make it easy
hes

Question 16

what scotoma size for reading

Answer 16

fluent- less than 4 degrees and if on macular less than 2 degrees
for spot-less than 30degrees nd 15 degrees for central
nasal and temporal more troublesome

Question 17

cv testing

Answer 17

ishiara- more a congenital test
macular disease mostly a blue-yellow defect and when results cross the circle the greater the severity
100 hue test- 85 colours- takes time- confusion line tells u type of defect



Question 18

confusion line defects

Answer 18

Protan- errors 15-26 deg and 58 to 68 deg
– Deutan- errors 12 to 17 deg and 53 to 60 deg
– Tritan- errors 4 to 6 deg
and 45 to 46 deg