Human can see using one of the sensors in the body which is the eye. Actually it is not the eyes seeing the thing but rather the light reflect on the object being seen stimulates the photo-sensitive cells (photo-receptors) in the retina of the eyes and sending the information to the brain to be processed into an image.
The problem of color blindness
Photo-receptors consist of rod and cone cells. There are 3 types of cone cells and every one is sensitive to the base color light which are red, green and blue. The eye see different colors due to the cone cells detect the different amounts of these basic colors.
When one or more of these cone cells is absent or fails to function normally, the eye cannot differentiate the colors as usual. A person with color blindness has trouble seeing red, blue, green and a mixture of these colors.
Many may think that being “color blind” mean can only see things in black or white and the shades of grey. This is always a misconception as it is extremely rare to be totally color blind as the failure to function may only affect one or 2 types of cone cells.
Therefore when people has the color blindness should be described as “color vision deficiency” to be more specifically.
The causes of color blindness
Most color vision defects are genetic and are present at birth. It is estimated between 5 – 8 % of men and 0.5% of women have color vision defects, thus making this quite a common condition.
The most common color vision defect affects red and green. The gene for red-green vision defect is located in the X chromosome, one of the 2 sex chromosomes.
In males (who have only one X chromosome), one defective copy of the gene is sufficient to cause the color blind. Else the females (who have 2 chromosomes), a mutation must be present in both copies of the gene to cause the disorder. That is why males are more frequently affected than females.
Some other forms of color vision problems are caused by the age-related disease such as cataracts, eye injury or side effects of some medicine.
The symptoms of color vision defect vary from one person to another. In some cases where the condition is not so critical that the affected person may not be aware at all that they can see color different from normal people.
Those are moderately color defect cannot differentiate the actual color, many times they may see a few shades of colors. It is very rare that a person can only see black or white.
The diagnose and treatment
Color vision defect is normally diagnosed by using the pseudoisochromatic plate test. It is a combination of color dots arranged in the shape of a pattern. (usually a number or a alphabet)
People with color vision defect cannot identify the number pattern if compare with a normal person who can see the color pattern.
At the moment, there is no treatment for inherited color vision defect. But those caused by the age-related disease such as cataracts where the cataract can be removed to restore the normal color vision.
Color vision defect can have a significant impact on a person’s life. It may affect learning abilities, reading development and limit a person’s career choices.
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