Question

'Miosis' in eye refers to
A. Reduction in diameter of pupil
B. Increased diameter of pupil
C. Reduction division in retina
D. Shrinkage of eyeball

Answer 1

Miosis is the contraction of pupil due to the contraction of the sphincter muscle of the iris which causes the eye pupil to contract when you are in bright light.

Complete answer:
First of all you should know what miosis is to solve this question easily. Miosis is pupil contraction i.e., when you are in bright light then the pupil gets shrunk in order to protect the eye from keeping the light out. So, the shrinkage of the pupil is called miosis. If the pupil stays small even in the dim light then it means that there is some problem related to the eye or you can say the eyes are not working properly the way they should.
There is contraction of the sphincter muscle of the iris which further causes the eye pupil to become small or you can say the eye pupil becomes contracted. This pupil contraction is controlled by iris sphincter muscles and these muscles are controlled by the nerves which are originating from the center of the brain.
Let's look at options now, Option A is Reduction in diameter of pupil. This option is the correct one since miosis is the contraction of pupil or pupil becomes small in the bright light. Contraction of pupil means that there is reduction in the diameter of pupil and this refers to miosis. Therefore, this option is the correct one.
Moving to option B which is Increased diameter of pupil. This option cannot be the correct one because miosis is contraction of pupil and due to the contraction, diameter of pupil decreases not increases and hence it is incorrect.
Moving to option C which is Reduction division in retina. Miosis is related to pupil contraction not related to retina. Therefore, this option is incorrect as miosis does not refer to reduction division in retina.
Last option D is Shrinkage of eyeball. This option is also incorrect because miosis is shrinkage of pupil not the shrinkage of eye ball and thus it gets eliminated.

Thus, the correct answer is option A which is Reduction in diameter of pupil.

Note: Miosis is the contraction of pupil due to the contraction of the sphincter muscle of the iris, this sphincter iris controls miosis. Contraction of pupils means there is reduction in the diameter of pupil. But if this reduction in diameter of pupil is seen generally in dim light too, then there are some eye related issues.