Colour vision
Colour vision factDefective colour vision is not
‘colour blindness’
A normal eye has three colour receptors
• For red, green and blue light
• Responses are relayed to the brain
• Here they are mixed together to
perceive many thousands of colours
Colour vision defects• One receptor is missing
• One receptor is abnormal
• Two or even three receptors are missing– More rare– More serious problem
Defective colour vision is common
1 in 12 men (8 percent)
1 in 200 women (0.5%)
Defective colour vision causes
• Colour matching problems
• Colour naming problems
• Inability to perceive brightness of colours
Defective colour vision is inherited
• Present at birth
and remains
unchanged
• There is no
treatment
Everyday problems
• Recognising colour of traffic lights
• Seeing coloured flowers on trees
• Judging ripeness of fruit
• Knowing when meat is cooked
Careers that require normal colour vision
• Airline pilot
• Air traffic
controller
• Train and tram
driver
• Policeman
• Fireman
• Careers in the
defence forces
• Seafarer
Normal colour vision is helpful for
• Painters and
decorators
• Fashion industry
• Colour mixers
• Medicine
• Artists
Colour is used in schools for teaching purposes
Therefore all children
should have their
colour vision tested
Testing for colour vision problems
• Ishihara test
• Very reliable
• Takes a few minutes
• > 3 errors means fail
• Follow up is necessary
Defective colour vision varies in severity
• The Ishihara test doesn’t measure the
extent of the defect
• Further tests are required to assess this
• Follow up can be provided by an optometrist
or ophthalmologist
Optometrists
• Provide a comprehensive visual
examination
• Detect and diagnose eye health problems
• Prescribe and supply glasses and contact
lenses when required
• Diagnose and treat eye coordination and
focussing problems
Optometrists
• Are university educated and
undertake continuing professional
education
• No referral is required
• Eye tests attract a medicare
rebate
To find an optometrist
• Optometrists Association Australia
www.optometrists.asn.au
• Yellow Pages