How eye sees color? How does the eye perceive color? Can you see color in the dark? Can drugs cause colored vision?

There are special light-sensitive cells in the retina termed cones which are responsible for color vision. However, they work only in bright light. In the dark it is almost impossible to tell the color of an object.

There are a number of theories as to how the eye perceives color. The best accepted is the theory of trichromacy.

There are three separate receptors in the cones of the retina for the three primary colors—red, blue and green. For example, to see a yellow shirt, the red and green receptors would be stimulated and would individually signal the brain which would perceive the combination as yellow.

People who have difficulty in distinguishing colors are called color-blind. However, the term is a misnomer, for very few people are really "blind" to color. They have difficulty in telling shades of color apart, and hence the correct term should be color-deficient. Some are deficient in one or two colors but can distinguish the others.

Thus, for an engine driver or for that matter, even a car driver, the inability to tell red and green apart can result in disastrous accidents.

However, a great deal of research has finally fructified in a special contact lens, which can help to tell the gross colors apart, known as an X-Chrom lens.

What is not commonly known by most people is that a number of diseases or drugs can effect color vision. Chlorpromazine, an anti-allergy drug, can cause brown vision, barbiturates yellowish, quinine mild reddish and griseofulvin gives green vision.

Early detection of color-blindness is simple with the use of color-graded charts. Occupations like a chemist's, an interior decorator's or a pilot's need acute color vision; hence it is important to know in advance that one is not color-blind. Often one finds out too late to be able to select an alternative occupation.

Dustin Flores

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