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Evaluation of colour- correcting lenses Vien Cheung Research Fellow in Colour and Imaging Science [email protected] CREATE 2010
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Evaluation of colour-correcting lenses
Vien Cheung
Research Fellow in Colour and Imaging Science
CREATE 2010
Human Visual System
wavelength nm
rela
tive
sens
itivi
ty
S M LRod
Colour blindness (deficiency)
males (%) females (%)
Anomalous Trichromacy 6.30 0.40
Protanomally (L cone) 1.30 0.02
Deuteranomally (M cone) 5.00 0.35
Tritanomally (S cone) <0.0001 <0.0001
Dichromacy 2.40 0.03
Protanopia (L-cone missing) 1.30 0.02
Deuteranopia (M-cone missing) 1.20 0.01
Tritanopia (S-cone missing) <0.001 0.03
Rod Monochromacy (no cones) <0.00001 <0.00001
Anomalous trichromats have three cone classes but one of the cones is normally shifted to a different peak wavelength sensitivity.
Dichromats possess only two cone classes.
What is it like to be a dichromat?
tritanope (blue-yellow) deuteranope (red-green) protanope (red-green)
Testing colour blindness
Farnsworth-Munsell 100 hue test Ishihara test
Solution for colour-defective vision?
ColorView A1 lenses
ColorView lenses, tinted with active coating, have specific spectral permeation characteristics.
ChromaGen coloured lenses have specific density and hue that (it is claimed) improve colour discrimination in 97% of people with colour-blindness problems
ChromaGen lenses
Evaluation of colour-correcting lenses
Deuteranomalous (M cone)
Color View A5
Ishihara Test
Farnsworth-Munsell 100-hue Test
Hypothesis – the lenses improve colour vision in some areas of colour space but at the expense of making colour discrimination worse in other areas of colour space.
Results
before
after
12 out of 25
25 out of 25
Ishihara Test
30
210
60
240
90
270
120
300
150
330
180 0
Results
Farnsworth-Munsell 100-hue Test
Error scores are noted when transpositions are made:
4 marks = each 2-cap transposition 8 marks = each 3-cap transposition
0-16 = superior discrimination
20-100 = average discrimination
Results
Farnsworth-Munsell 100-hue Test
Discussions
Ishihara Test - results were significantly improved when the colour-correcting lenses were applied. The observer responded correctly for all 25 plates with very little hesitation.
Farnsworth-Munsell 100-hue Test - errors lie predominantly on yellow/green and blue/purple region supports the optician’s diagnosis of the observer being deuteranomalous.
The correction lenses did not improve the observer’s colour discrimination but rather induced greater deficiency.
The results suggest that wearing colour-correcting lenses of the type used in this study could enable an observer to pass a screening test for colour deficiency.
