Colour blind is a figurative term. The person who has this unfortunate disorder is not actually blind but his or her ability to distinguish between colours is diminished or absent. It is a hereditary disease that happens due to damaged genes. If you are colour blind, then there are chances that you have other vision problems too but such a thing is not mandatory.
How does a colour blind person see?
Just as we do but, with some minor impairments. We do not see with our eyes but the retina that is their behind our eyesballs. The retina has rod and cone cells that are photo sensitive. The rod cells are active under low light and cone cells under day light or natural light. There are 2 types of cone cells corresponding to the 3 primary colours of the spectrum; red, blue and green. Any defects in the cone cells can cause colour blindness. There are 3 main types of colour blindness.
3 Types of colour blindness:
Not every one who is colour blind sees in the same way. There are basically 2 types of colour blindness; complete and partial. Complete colour blindness is a relatively rare condition. It happens due to the complete absence of cone cells. Partial colour blindness is more commonly occurring. Here, the cone cells are not absent but damaged.
The partial impairment reduces your ability to see any one of the 3 primary colours properly. This makes your world two dimensional. There are types of confusion arising from this disorder; the red green dichotomy where you cannot distinguish between these 2 main colours. The other is a confusion between the blue and yellow colours.
Is there a test for colour blindness?
If you have never seen a colour properly, how will you know that you are seeing it incorrectly. Thus, some people are colour blind without their knowledge for years. There is a colour blindness test called the Ishihara Color Test for kids. This test uses specific coloured spots to determine your photo senses.
Does it run in the family?
A majority of colour blindness, especially, the partial red-green type, is hereditary. It is often more pronounced in men than in women. This gender selective appearance has simple genetic explanation. The genes for colour vision are located on the X chromosome. Women have a pair of X chromosomes and just one is enough to give you clear coloured vision. So, the men with just one X in their genetic makeup are at the receiving end of colour blindness!