Our world is full of colors. We can view all the colors through vision. People suffering from the color vision defects can see all these colors in another way. It usually ocurs due to the problems in the color pigments in the nerve cells of the eye called cones. Cone cells are present in the retina (light sensitive layer of the tissue)of the eye.
Color blindness shows diversified symptoms and varies to each person.
It may include:-
Mild symptoms seen in childhood like difficulty of the child to learn colors.
Your eye doctor can do an eye examination and check for colorblindness. Ishihara plates test is the widley used test for identifying color blindness.
Although color blindness has no treatment, some techniques and glasses are useful for the individuals with color blindness. They help the color blind people to distinguish between the colors which they cannot see with naked eye.
Color blindness is mostly a X-linked recessive hereditary disease. The chances of color blindness in men is 1 in 10 and it is less frequent in women.
Some drugs like hydroxychloroquine can also be the cause of color blindness.
Color blindness can also occur due to some eye diseases like damage to retina and macula and darkening of the lens as a result of cataract.
The retina of the eye consists of cells called rods and cones. The cones are responsible for the distinction of colors and shades of it. The cones cells are made up of light sensitive pigments of various wavelenghts. Three different types of cones are present. Blue,red and green cones are sensitive to different wavelengths.
The deficiency of cones can occur in infants or later in childhood. Cone cells are not sensitive to those particular wavelengths and hence cannot differentiate between the colors.
Difficulty to observe the brightness is caused as a result of absence of cone cells resposible for green and red color.
Color vision defects are differentiated into mainly three types-
1) Red-green color vision defect which occurs prominently in men rather than women. In this type of color blindness, individuals cannot differentiate between the red and the green color. It is popular type of color blindness .
2) Blue-yellow color vision defect results in difficulty in identifying blue and yellow and somtimes red and green too.
3)Absolute absence of color vision-Achromatopsia- It is the most severe type of color blindness. In this condition the individual is not able to see any color. It is aslo associated with other disorders like lazy eye, nystagmus, photophobia and very poor visual acuity.
Color Blindness can also be distinguished as
It is associated with the shift in sensitivity of pigments in cones. Anomalous Trichromacy further subdivided as
In this type of color blindness, one pigment in cones is absolutely absent.
Dichromacy is further subdivided as
|Overall (United States)||—||—||—|
|Red–green (Overall)||7 to 10%||—||—|
|Protanopia (red deficient: L cone absent)||1% to 1.3%||0.02%||—|
|Deuteranopia (green deficient: M cone absent)||1% to 1.2%||0.01%||—|
|Tritanopia (blue deficient: S cone absent)||0.001%||0.03%||—|
|Protanomaly (red deficient: L cone defect)||1.3%||0.02%||—|
|Deuteranomaly (green deficient: M cone defect)||5.0%||0.35%||—|
|Tritanomaly (blue deficient: S cone defect)||0.01%||0.01%||—|