Contrast Sensitivity

Question 1

Indications

Answer 1

Evaluation of vision that can’t be predicted with VA testing @ 100% contrast

Screening for early ocular disorders (when suspecting)

Monitor VFx

Prediction of vision-related ability

Question 2

Effect of disease on CSF

Answer 2

Spherical RE = loss at high SF
AMD, macular oedema, cataract = low-medium SF (hidden loss)
Astigmatic RE, monocular diplopia = may prod. notch defect (rare)

Many conditions produce generalised loss, particular with advancing disease

Question 3

What visual pathway disorders can be screened?

Answer 3

Optic neuritis & MS
Parkinsons D
Papilloedema
POAG
DR
Compressive lesions

Question 4

What is the SF equivalent of 3cpd and 30cpd?

Answer 4

3cpd = 6/60
30cpd = 6/6

Question 5

Shape of CSF varies with…

Answer 5

luminance, temporal characteristics, target size, grating motion and shape (sine vs square)

Question 6

Pelli Robson chart

Answer 6

Measure of peak CS
16 triplets, same size letters, constant SF (1.25cpd)
@ 1m, monocular

Normative:
≤50 yo - 1.80 log units
>50yo - 1.65 log units

Question 7

Melbourne Edge test (MET)

Answer 7

Measures contrast of a single edge
20 circular stimuli, 2.5mm diameter
@40cm
4AFC - Determine edge orientation
Decreases in 1dB steps

Normative:
65yo: 16-18dB

Abnormal:

Question 8

Australian Vision Chart

Answer 8

Measures slow of CSF function
Presentation of high contrast (90%) vs low contrast (10%) charts side by side
@40-60cm, record number of lines of diff. b/w charts

Normative:
65yo: 2.5 lines
Abnormal: >3 lines, or change if ≥3 lines between tests

Question 9

Glare tests

Answer 9

Photostress eye for 10s using BAT
Measure time to recover to post-stress VA monocularly

Normal: 60s or difference between eyes

Question 10

What can be done to aid with reduced CS?

Answer 10

BIGGER - moves object from non seeing domain to seeing domain (horizontally)

BOLDER - increases contrast, moves object vertically downwards

BRIGHTER - lifts peak of reduced CSF to include low contrast task