Colour Blindness Test
is a test for colour blindness or to use a better but less
common term, colour vision deficiency. Most so-called "colour
blind" individuals are not truly colour blind but instead
have abnormal colour vision. They only have problems distinguishing
certain colours and shades of the same colour. They do not
see only in black and white. True inability to distinguish
any colours is actually rare.
Interpreting the results
If you are unable to see the number 15 and 29 respectively,
you suffer from faulty colour vision. There is no cause for
concern if you are already a known sufferer from defective
colour vision from previous testing. There is no cure for
hereditary colour blindness. However, if you previously had
normal colour vision but now have faulty colour vision, you
should see your eye doctor for an eye examination.
Understanding More About Colour Blindness
It is estimated that eight percent of males and fewer than
1 percent (about 1 in 200) of females are colour deficient.
Most people suffering from colour blindness are born with
the condition. They inherit the condition from their parents
as an 'X-linked trait'. This means that the gene causing the
condition is located on the X sex chromosome. Males have an
X and a Y sex chromosome, while females have a pair of X sex
Genetically, this means
males are predominantly affected.
females are not predominantly affected but are carriers
of the defective genes. Carriers carry the gene and can pass
it on to half their sons. Half their daughters can be carriers.
Carriers themselves are not affected by the defect.
if the father is colour blind, all his daughters will be
female carriers of the defective genes. All his sons will
if the mother is colour blind, all her sons will be affected
and all her daughters will be female carriers.
Green colour weakness or blindness is most common, followed
by red colour weakness or blindness. It is important to remember
that not all cases of colour blindness are congenital as there
are some diseases acquired later in life, like diabetic eye
disease, glaucoma, retinal or optic nerve disease which may
disrupt colour vision.
The Importance Of Colour Vision Testing
It is important to know if you are colour blind. Colour is
often used as an aid to teaching in pre-primary and primary
schools. Children who have difficulty distinguishing between
colours may be misdiagnosed as having learning difficulties
unless it is known beforehand that they have a colour vision
defect. Knowing the existence of a colour vision defect early
can thus help prevent communication problems in school and
in later adult life.
Schoolchildren with colour vision defect should think over
carefully before choosing study subjects where colour discrimination
is important. Art and chemistry are two examples of such subjects.
Consider colour deficiencies when making career decision.
This is because many occupations demand good colour discrimination.
Defective colour vision is a handicap in some pharmacy and
chemistry jobs. Colour is often used to convey important information
such as in traffic and navigational lights and colour coding
of electrical wires.
How We See Colour
Our eyes are capable of differentiating an infinite array
of colours. Yet, would you believe that all our colour sensations
are actually derived from varying stimulation of only three
types of colour receptors, namely red, green and blue?
These receptors, called cones, are found solely in the centre
part of the retina in an area called the macula. The retina
is the nerve layer lining the back of the eye, much like the
film in a camera.
The colours red, green and blue are also known as the primary
colours. A suitable mixture of these three colours can produce
any colour including white!
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