Question

What is colour blindness? What kind of retinal cells are lacking in a person suffering from this defect?

Answer 1

Hint: Color blindness is a genetic defect that causes deficiency to distinguish between colors. One who suffers from this disease cannot differentiate between colours which is extremely rare but a common symptom of this disease is that they are not able to fully see red, green or blue light.

Complete answer:
Color blindness or we call it colour deficiency is the ability of eyes to see the colors. It is a defect in which a person is not able to distinguish between red, green and blue light. These forms of vision deficiency disrupt color perception but it does not affect the sharpness of the vision.

The most common cause of this problem is that it is an inherited problem in the development of one or more sets of the eyes' cone cells. Among humans, males are more likely to face this problem because it is present on the X chromosome. Females have two X chromosomes, so the defect is typically compensated for by one by another. Non- color blind females can carry genes for color blind ones and they can pass that to their progeny.

Male have only one X chromosome so they always express the genetic disorder if they have the recessive gene. Color blindness can result in damage to the eye chemically or the optic nerve or part of the brain is damaged.

In the retina, humans have two types of photoreceptor cells called rods and cones. These cells contain light sensitive proteins called photopigments. Day and color vision is given by cones cells. Human eye contains three types of cones which possess their own characteristic photopigments that respond to red, green and blue light. The sensation of different colors are produced by various combinations of these cones and their photopigments. So, a person suffering from this disease lacks cone cells.

Note: A less common and a severe form of color blindness vision deficiency is blue cone monochromacy that causes poor visual acuity and severely reduced color vision. The one who are affected by this problem have additional problems like increased sensitivity to light, involuntary back and forth eye movement and nearsightedness. Sometimes it is also considered as achromatopsia, a disorder characterised by lack of color vision with several other problems.