Intermediate
Technical
IVT
miosis
Pronunciation: my-OH-sis
Constriction of the pupil to smaller than normal size.
Full Definition
Miosis is the constriction of the pupil to a diameter smaller than normal (typically less than 2mm in normal lighting conditions). This condition can result from increased parasympathetic stimulation, decreased sympathetic stimulation, or the effects of certain medications such as opioids or cholinergic agents. Pathological miosis may indicate Horner's syndrome, pontine lesions, or drug intoxication. The term is often confused with 'meiosis,' which refers to a type of cell division.
Usage
Usage note: Do not confuse with 'meiosis' (cellular division process). Note the spelling difference.
In Context
- "The patient presented with bilateral miosis consistent with opioid intoxication." — Emergency department evaluation
- "Unilateral miosis accompanied by ptosis suggested Horner's syndrome." — Neurological examination
Also known as
pupillary constriction
pinpoint pupils
Contrasted with
mydriasis
pupillary dilation
Don't confuse with
meiosis
mydriasis