Editing Pupil (section)

===Effect of drugs===
If the drug pilocarpine is administered, the pupils will constrict and accommodation is increased due to the parasympathetic action on the circular muscle fibers, conversely, atropine will cause paralysis of accommodation (cycloplegia) and dilation of the pupil.

Certain drugs cause constriction of the pupils, such as [[opioids]].<ref>{{Cite journal|last=Larson|first=Merlin D.|date=2008-06-01|title=Mechanism of opioid-induced pupillary effects|journal=Clinical Neurophysiology|volume=119|issue=6|pages=1358–64|doi=10.1016/j.clinph.2008.01.106 |pmid=18397839|s2cid=9591926}}</ref> Other drugs, such as [[atropine]], [[LSD]], [[MDMA]], [[mescaline]], [[psilocybin mushrooms]], [[cocaine]] and [[amphetamines]] may cause pupil dilation.<ref>{{Cite journal|url=https://www.csam-asam.org/sites/default/files/pdf/misc/Howtospot.pdf|title=How to spot illicit drug abuse in your patients|last=Johnson|first=Michael D.|date=October 1, 1999|journal=Postgraduate Medicine|volume=106|issue=4|pages=199–200, 203–6, 211–4 passim|doi=10.3810/pgm.1999.10.1.721|pmid=10533519|access-date=March 22, 2018}}</ref><ref>{{Cite journal|last1=Alderman|first1=Elizabeth M.|last2=Schwartz|first2=Brian|date=1997-06-01|title=Substances of Abuse|url=https://pedsinreview.aappublications.org/content/18/6/204|journal=Pediatrics in Review |volume=18|issue=6|pages=204–215|doi=10.1542/pir.18-6-204 |s2cid=73382801 }}</ref>

The sphincter muscle has a parasympathetic innervation, and the dilator has a sympathetic innervation.  In pupillary constriction induced by pilocarpine, not only is the sphincter nerve supply activated but that of the dilator is inhibited.  The reverse is true, so control of pupil size is controlled by differences in contraction intensity of each muscle.

Another term for the constriction of the pupil is [[miosis]]. Substances that cause miosis are described as miotic.  Dilation of the pupil is [[mydriasis]].  Dilation can be caused by mydriatic substances such as an eye drop solution containing [[tropicamide]].