Color Vision and Color Color Vision and Color DeficienciesDeficiencies

Jane Jane PhilippsPhilipps and and NallelyNallely GarciaGarcia

OverviewOverview

•• How Do We Perceive Color?How Do We Perceive Color?

•• Color DeficienciesColor Deficiencies

•• Tests for Color DeficienciesTests for Color Deficiencies

•• Our Test ResultsOur Test Results

•• How Do Color Deficiencies Limit People?How Do Color Deficiencies Limit People?

How Do We Detect and See Light?How Do We Detect and See Light?

Fovea• Light enters eye

• Focused by cornea and lens onto back of retina

• Photoreceptors absorb light

• Light is transformed into electrical signals

• Signals sent to brain via optic nerve

RodsRodsFor Night VisionFor Night Vision> 90 % of Photoreceptors> 90 % of PhotoreceptorsNone in FoveaNone in Fovea

ConesConesFor Day VisionFor Day Vision< 10 % of Photoreceptors< 10 % of PhotoreceptorsConcentrated in FoveaConcentrated in Fovea

Two types of Photoreceptors in RetinaTwo types of Photoreceptors in Retina

Rod Cone

http://www.lightenergysource.com/LES%20-%20Rods%20&%20Cones.jpg

http://hyperphysics.phy-astr.gsu.edu/hbase/vision/imgvis/rcdist.gif

Cones are Responsible for Color VisionCones are Responsible for Color Vision

Three Types:

Long (L, Red) 62%

Medium (M, Green) 31%

Short (S, Blue) 7%

0

20

40

60

80

100

120

340 380 420 460 500 540 580 620 660 700Wavelength (nm)

Abs

orba

nce

S Rod M L

Images of Cones in the Fovea

* A. Roorda & D.R. Williams, Nature 1999H. Hofer, J. Carroll, D.R. Williams

*

*

*

5 arcmin

16:1

1:3

How Do People Get Color Deficiencies?How Do People Get Color Deficiencies?

Genetic• Color Deficiencies are recessive traits carried on X chromosome

• Females have XX, Males have XY – Males have a greater chance

• 8 % of Caucasian males have a Red/Green Color Vision Deficiency

• 15 % of Caucasian females carry Color Vision Deficiency genes

Acquired• Eye Disease, Drug Use, Overexposure to Lead or Mercury, Injury to

eye or brain

• Equal Chances for Males and Females

Types of Color Deficiencies

Normal Color VisionTrichromacy - Three Cone Types (L, M and S)

Color DeficienciesAnomalous Trichromacy

Three Cone Types - One Has Altered SensitivityDichromacy

Two Cone TypesBlue Cone Monochromacy

One Cone Type (S only)Rod Monochromacy

No Cone Types, Only Rods

DichromacyDichromacy and Anomalous and Anomalous TrichromacyTrichromacyRed/Green Color Deficiencies

Protan – L Cone Deficiency• Protanomalous – altered sensitivity• Protanope – missing

Deutan – M Cone Deficiency• Deuteranomalous – altered sensitivity• Deuteranope – missing

Blue/Yellow Color Deficiency

Tritan – S Cone Deficiency• Tritanope – missing

Normal (S,M,L) Protan or Red/Green (S,M)

Deutan or Red/Green (S,L) Tritan or Blue/Yellow (M,L)http://webexhibits.org/causesofcolor/2.html

Screening Tests for Color DeficienciesScreening Tests for Color Deficiencies

AO-HRR

C100

ISHIHARAD15

AOAO--HRR HRR –– PseudoisochromaticPseudoisochromatic PlatesPlates

•• Tests for Tests for ProtanProtan, , DeutanDeutan, , TritanTritan

•• Subject must identify and Subject must identify and trace shapes on platestrace shapes on plates

AOAO--HRR ResultsHRR Results

•• 20 subjects tested20 subjects tested•• 10 males10 males•• 10 females10 females

•• 1 1 protanprotan (male)(male)•• 1 1 deutandeutan (male)(male)•• 18 normal18 normal

•• 8 males8 males•• 10 females10 females

Ishihara Ishihara –– PseudoisochromaticPseudoisochromatic PlatesPlates•• Tests for Tests for ProtanProtan, , DeutanDeutan•• Subject must read numbers they seeSubject must read numbers they see

Normal Color Vision

Ishihara Ishihara –– PseudoisochromaticPseudoisochromatic PlatesPlates•• Tests for Tests for ProtanProtan, , DeutanDeutan•• Subject must read numbers they seeSubject must read numbers they see

Protan Color Vision

Ishihara ResultsIshihara Results

•• 22 subjects tested22 subjects tested•• 10 males10 males•• 12 females12 females

•• 1 1 ProtanProtan (male)(male)•• 1 1 DeutanDeutan (male)(male)•• 20 normal20 normal

•• 8 males8 males•• 12 females12 females

DD--1515

•• Tests for Tests for ProtanProtan, , DeutanDeutan, , TritanTritan

•• Subject must Subject must arrange colored arrange colored disks by huedisks by hue

DD--15 Results15 Results

•• 21 Subjects tested21 Subjects tested•• 10 males10 males•• 11 females11 females

•• 1 1 ProtanProtan (male)(male)•• 20 normal20 normal

•• 9 males9 males•• 11 females

Normal

11 females

Protan

C100C100•• Tests for Tests for ProtanProtan, , DeutanDeutan•• Subject must find spot with least amount of Subject must find spot with least amount of

flickerflicker

C100 ResultsC100 Results

•22 Subjects

•11 males

•11 females

•1 Protan (male)

•21 Normal

•10 males

•11 females

C100 Test Results

012345678

-5 -4 -3 -2 -1 0 1 2 3 4 5

C100 Average Score

# of

Sub

ject

s

Protan DeutanNormal

How Can Color Deficiencies Limit Humans?How Can Color Deficiencies Limit Humans?Careers

Bus Driver, Firefighters, Police Officers, Paint Makers, Doctors, Chemists, Decorators, Computer Programmers

SchoolAffects Reading and Math Skills

Which Flask Contains the Pink Solution?

ConclusionsConclusions• Cone Photoreceptors are Used to Perceive Color

Long (L), Medium (M), and Short (S) Wavelength Sensitive

• Three Main Color Deficiencies

Protan (Missing or Altered L Cone)

Deutan (Missing or Altered M Cone)

Tritan (Missing or Altered S Cone)

• Color Deficiency Screening Tests and Results

1 Protan (AO-HRR, Ishihara, D-15, C-100)

1 Deutan (AO-HRR, Ishihara)

• Need to Conduct Several Tests for Accurate Diagnosis

AcknowledgementsAcknowledgements

Maribell Huerta

Hilary O’Bryan

David Lai

Gene Switkes

Jason Porter

Gary Martindale

Joe Carroll

COSMOS and CfAO