People who are totally blind are referred to as 'NLPS' no light perception and these people cannot even tell whether they are standing in the dark or whether there is light around them, where as people who have light perception are able to identify whether they are in the dark or in an area where there is light, then there are those people who have light projections sense i.e. that they are able to tell from which source the light is emitting. Color blindness is a term that is largely misleading because the term blind is misinterpreted, people who are color blind do not usually lose the ability so see all color, though this might happen in total color blindness but that happens in only very rare cases. The most common type of color blindness is only partial, because people cannot differentiate between certain colors or between a range of certain colors they are termed as being color blind because that in a way does affect the world that they see around them. Blindness and color blindness can be caused by various factors such as:
a) Diseases that effect the brain or diseases that effect the eye directly, also malnutrition in many a case...
s on the eye may be to blame for a loss in color vision or vision on the whole, eye diseases should be taken care of promptly because eye infections and diseases can lead to major visual impairment if let untreated.
c) Genetic factors are also another reason that people tend to suffer from blindness or color blindness and people who suffer from albinism often suffer from such visual impairment that they are given the status of legally blind.
d) Poisoning is also another reason why people can turn blind, a well known poison for turning people blind is methanol which is sometimes also used as a cheap substitute to alcohol.
Having stated the reasons and kinds of blindness it is important now to delve into how an eye works and therefore look into the reasons of color blindness. The eye basically have two receptor cells in the retina, the cone cells, which are active in normal day light and the rod cells which are active in low light conditions. There are basically 3 kinds of cones each containing a different pigment and hence cover the whole spectrum of color, a color blind person has some impairments in these cones and hence is not able to see colors the way normal people can.
The types of color blindness are as follows:
a)Dichromatic: These are people who have one of the cone cells missing and hence try to make up for this deficiency by trying to visualize all colors using only two of their cones and since this is virtually impossible they end up with some sort of a color deficiency.
b)Amalous Trichromacy: These individuals have all the cone cell but their sensitivities are some what different to the people who have normal color reception and because of this change in sensitivity they tend to mix some basic colors together and hence are not able to differentiate or