Pupil (Miosis)

Miosis refers to the excessive constriction of the pupil, resulting in a pupil diameter of less than 2 mm. It is a physiological response to bright light or near focus, but can also be caused by various pathological conditions, including neurological disorders, drug intoxication, and aging. The process is controlled by the sphincter pupillae muscle and the parasympathetic nervous system. Persistent or inappropriate miosis can be a sign of underlying health issues and is assessed as part of neurological examinations.

Other names

Pupillary constrictionMiosis

Pupillary constriction is primarily mediated by the contraction of the sphincter pupillae muscle, controlled by the parasympathetic nervous system. Drugs can induce miosis through various mechanisms, including activation of muscarinic receptors or inhibition of acetylcholinesterase.