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