MYOSIS Meaning and
Definition
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Myosis is a medical term derived from the Greek word "myein," meaning to shut or close. It refers to the physiological process of constriction or narrowing of the pupil in the eye. The pupil is the round, black aperture at the center of the iris that regulates the amount of light entering the eye. Myosis occurs due to the contraction of the muscles in the iris, causing the pupil to reduce in size diameter-wise.
This natural phenomenon is often an involuntary response triggered by various stimuli, including exposure to bright light, fear, pain, or certain medications. The primary function of myosis is to protect the delicate tissues within the eye from excessive brightness or potential harm. By constricting the pupil, less light enters the eye, minimizing potential damage to the retina and allowing for sharper focus on nearby objects.
Myosis is the opposite of mydriasis, which refers to the dilation or widening of the pupil. Both myosis and mydriasis are regulated by the autonomic nervous system, specifically the parasympathetic and sympathetic divisions.
Abnormal or persistent myosis may occur in certain medical conditions, such as Horner's syndrome or opioid drug use. Diagnosing the underlying cause of abnormal myosis often requires a thorough medical evaluation, including a detailed history, ocular examination, and possibly additional diagnostic tests. Treatment for myosis depends on the underlying cause and may involve addressing the specific condition responsible or discontinuing medications contributing to the abnormality.
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Contraction of the pupil, miosis.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
Common Misspellings for MYOSIS
Etymology of MYOSIS
The word "myosis" comes from the Greek term "musis", which means "a shutting". The prefix "my-" means "less" or "reduced", indicating that "myosis" refers to the contraction or narrowing of the pupil.
Similar spelling words for MYOSIS
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