The word miosis is the medical term used to refer to the fact that the pupils become pinpoint. That is, it consists of the contraction of the pupil. Although it may seem irrelevant, pupil size can tell a lot about a person’s health.
This part of the eye reacts physiologically to changes in light, contracting or dilating. But in addition, its size varies when toxic substances are consumed or there is a brain injury. Therefore, we explain everything you need to know about miosis.
What is miosis?
Miosis, as we have just pointed out, consists of the contraction of the pupil. The pupil is the hole in the center of the iris, that is, the dark part of the eye. It is responsible for controlling the amount of light that passes into the eyeball, towards the retina.
To do this, it can expand or contract, depending on how much light is in the environment. Thus, when the environment is dark, it dilates (which is called mydriasis ). On the contrary, when there is a lot of lighting, the pupil contracts. It is a normal and physiological reflex controlled by the parasympathetic nervous system.
These movements are carried out thanks to a muscle present in the eye called the ciliary muscle . When the pupil is dilated, the muscle that works is the dilator of the iris. In that case, the sympathetic nervous system is the one that coordinates the action.
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