Aconstriction response (miosis),[2] is the narrowing of the pupil, which may be caused by scleral buckles or drugs such asopiates/opioids or anti-hypertension medications. Constriction of the pupil occurs when thecircular muscle, controlled by theparasympathetic nervous system (PSNS), contracts, and also to an extent when theradial muscle relaxes.
A human adult exhibiting voluntary control over his iris muscles, where he can cause his pupil to dilate and constrict on command
Adilation response (mydriasis), is the widening of the pupil and may be caused byadrenaline;anticholinergic agents;stimulant drugs such asMDMA,cocaine, andamphetamines; and somehallucinogenics (e.g.LSD).[3] Dilation of the pupil occurs when the smooth cells of theradial muscle, controlled by the sympathetic nervous system (SNS), contract, and also when the cells of the iris sphincter muscle relax.
Constricted (left) and dilated (right) pupil of the same eye
Some humans have the ability to exert direct and voluntary control over theiriris sphincter muscles anddilator muscles, granting them the ability to dilate and constrict their pupils on command, regardless of lighting condition and/or eyeaccommodation state.[15] However, this ability is very rare, and its potential use or advantages are unclear.
Thelatency of pupillary response (the time in which it takes to occur) increases with age.[16]
Inophthalmology, intensive studies of pupillary response are conducted via videopupillometry.[17]
Anisocoria is the condition of one pupil being more dilated than the other.
Scheme showing sympathetic and parasympathetic innervation of the pupil and sites of lesion in a Horner's syndromeSympathetic connections of the ciliary and superior cervical ganglia
^Baker LE (1938). "The Pupillary Response Conditioned to Subliminal Auditory Stimuli". Ohio State University.OCLC6894644.{{cite journal}}:Cite journal requires|journal= (help)
