Business Hours

Monday to Friday - 8.30am to 5.30pm
Saturday - 8.30am to 4.00pm

 

Colour Vision

What is colour blindness?

Colour blindness, or colour vision deficiency, results from an absence or malfunction of certain colour-sensitive cells in the retina. The retina is the nerve layer at the back of the eye that converts light into nerve signals that are sent to the brain.

 A person with colour blindness can have trouble seeing red, green, blue, or mixtures of these colours. This means that they will confuse some colours, and/or not see some colours as brightly as other people. It is very rare for a person to be unable to distinguish between any colours at all, so the term 'colour blind' is not really accurate.

Why is colour vision important?

Colour is used constantly as a means of communicating information.

Children in their early grades at school are taught through the use of colour and their learning can be hampered by not being able to see colours properly. It is important for your child's colour vision to be checked before he or she enters school. In knowing if your child is colour vision deficient, you will be able to minimise learning difficulties that your child may have.

Many occupations-such as pilots, clothes designers and painters-require the ability to discriminate accurately between colours. Students who know they are colour vision deficient can avoid choosing and studying for careers that require fine colour discrimination.

People with a colour vision deficiency may not see traffic lights and other warning signals; however, many people learn to compensate for their problem in various ways.

Who has colour vision deficiency?

Colour vision problems are usually genetic, but can also be acquired as a result of aging, eye disease or injury. Some acquired problems may be treated; however, inherited colour-blindness cannot. Eight per cent of men and approximately 0.5 per cent of women have colour vision problems. These vary in severity; very few people have complete colour blindness.

Often people will be unaware that they do not see colours properly because they have found ways of overcoming the difficulties.

How is it diagnosed?

Full diagnosis is possible at Heming Scott & Donald with the D15, Medmont C100 & Ishihara Plates. These tests can reveal the type and severity of any colour vision problems.

Ask us for these related brochures:

• School achievement and vision
• Driving and vision

An interesting colour vision site.

Assessment of colour vision for bus and coach drivers for Road Traffic Authority (RTA) requirements is available.

TESTS

• D15: You will be asked to arrange a series of coloured chips. People with impaired colour vision will be unable to arrange the chips correctly.
• Medmont C100: This is an electronic colour vision-screening device, which is used to rapidly detect red/green colour vision deficiencies. The instrument displays a small flickering test light. The patient turns a knob until the light appears to flicker least. This gives a reading on the indicator, which is used to distinguish between protan (red-green) and deutan (green-red) colour deficiency.
• Ishihara Plates: These show a series of coloured dots, within which arrangement certain figures or symbols should appear to those with good colour vision. Some are more difficult to discern than others.

Ishihara plate