Miosis is defined as constriction of the pupil due to contraction of the musculus sphincter pupillae or decreased activity of the musculus dilatator pupillae. Miosis represents the eye’s physiological response to a strong light stimulus and is mediated by the parasympathetic nervous system. Miosis is the opposite of Mydriasis.
Figure
Clinical relevance
Miosis together with Ptosis may be pathognomonic for Dissection of the Internal carotid artery.