Colour blindness occurs when an individual is unable to see colours in a
normal way. Most commonly, colour blindness (also known as colour deficiency)
happens when someone cannot distinguish between certain colours, usually
between greens and reds, and occasionally blues.
normal way. Most commonly, colour blindness (also known as colour deficiency)
happens when someone cannot distinguish between certain colours, usually
between greens and reds, and occasionally blues.
In the retina (the light-sensitive tissue lining the back of the eye),
there are two types of cells that detect light: rods and cones. Rods detect
only light and dark and are very sensitive to low light levels. Cone cells
detect colour and are concentrated near the centre of your vision. There are
three types of cones that see colour: red, green and blue. The brain uses input
from these three colour cone cells to determine an individual colour
perception.
there are two types of cells that detect light: rods and cones. Rods detect
only light and dark and are very sensitive to low light levels. Cone cells
detect colour and are concentrated near the centre of your vision. There are
three types of cones that see colour: red, green and blue. The brain uses input
from these three colour cone cells to determine an individual colour
perception.
Colour blindness can occur when one or more of the colour cone cells are
absent, non-functioning, or detect a different colour than normal. Severe colour
blindness occurs when all three cone cells are absent, and mild colour
blindness occurs when all three cone cells are present, but one cone cell
functions abnormally to detect a different colour than normal. There are
different degrees of colour blindness. Some people with mild colour deficiencies
can see colours normally in good light but have difficulty in dim light. Others
cannot distinguish certain colours in any light.
absent, non-functioning, or detect a different colour than normal. Severe colour
blindness occurs when all three cone cells are absent, and mild colour
blindness occurs when all three cone cells are present, but one cone cell
functions abnormally to detect a different colour than normal. There are
different degrees of colour blindness. Some people with mild colour deficiencies
can see colours normally in good light but have difficulty in dim light. Others
cannot distinguish certain colours in any light.
Signs and symptoms of colour blindness
The signs and symptoms
of colour blindness can range from mild to severe. The symptoms include:
of colour blindness can range from mild to severe. The symptoms include:
- Trouble seeing colours and the brightness of colours
in the usual way; - Inability to tell the difference between shades
of the same or similar colours, particularly red and green, or blue and yellow.
Types of colour blindness
Based on
clinical appearance, colour blindness may be described as partial or total.
clinical appearance, colour blindness may be described as partial or total.
·
Partial colour blindness: There are two major types of partial colour
blindness. This is known as red – green and blue – yellow colour blindness.
People with red – green have difficulties in differentiating red and green
colours while those with blue – yellow colour blindness have difficulties in
differentiating blue and yellow colours.
Partial colour blindness: There are two major types of partial colour
blindness. This is known as red – green and blue – yellow colour blindness.
People with red – green have difficulties in differentiating red and green
colours while those with blue – yellow colour blindness have difficulties in
differentiating blue and yellow colours.
·
Total colour blindness: Total colour blindness is defined as the inability to see colour.
Total colour blindness: Total colour blindness is defined as the inability to see colour.
Causes of
colour blindness
colour blindness
Causes of colour blindness can
be grouped into genetic and other causes.
be grouped into genetic and other causes.
·
Genetics: Genetically
related colour blindness is typically inherited. Inherited colour blindness can
be congenital (from birth), or it can commence in childhood or adulthood.
Genetics: Genetically
related colour blindness is typically inherited. Inherited colour blindness can
be congenital (from birth), or it can commence in childhood or adulthood.
·
Other causes: Other causes of colour blindness include brain or retinal damage caused
by shaken baby syndrome, accidents and other trauma which produce swelling of
the brain in the occipital lobe, and damage to the retina caused by exposure to
ultraviolet
light.
Other causes: Other causes of colour blindness include brain or retinal damage caused
by shaken baby syndrome, accidents and other trauma which produce swelling of
the brain in the occipital lobe, and damage to the retina caused by exposure to
ultraviolet
light.
The role of the family in the control of colour
blindness
blindness
Family members can help people with colour blindness by helping them
understand better, the nature of their health condition and assist them in their
areas of deficiency to enhance the quality of their lifestyle.
understand better, the nature of their health condition and assist them in their
areas of deficiency to enhance the quality of their lifestyle.
The role of the community in the control of colour
blindness
blindness
Community leader should form a support group for people with colour
blindness to assist them. In cases where colour blindness can lead to danger
such as inability to read traffic light correctly, there should be measure put
in place to ensure that these set of people are well cared for.
blindness to assist them. In cases where colour blindness can lead to danger
such as inability to read traffic light correctly, there should be measure put
in place to ensure that these set of people are well cared for.
The role of government in the control of colour
blindness
blindness
Since there is no treatment for colour blindness, government should
provide contact lenses and glasses that may help people with colour blindness
tell the difference between similar colours, while acquired forms of colour
blindness may be treated by addressing the underlying condition or drug that
caused the problem.
provide contact lenses and glasses that may help people with colour blindness
tell the difference between similar colours, while acquired forms of colour
blindness may be treated by addressing the underlying condition or drug that
caused the problem.