Pupillary response
Pupillary response is a physiological response that varies the size of the pupil, either resulting in constriction (miosis)[1] or dilation (mydriasis, expansion), via activation or deactivation of the iris dilator muscle. The response can have a variety of causes, from an involuntary reflex reaction to exposure or inexposure to light — in low light conditions a dilated pupil lets more light into the eye — or it may indicate interest in the subject of attention or indicate sexual stimulation.[2] The pupils contract immediately before someone falls asleep.[3] A pupillary response can be intentionally conditioned as a Pavlovian response to some stimuli.[4]
The latency of pupillary response (the time in which it takes to occur) increases with age.[5] Use of central nervous system stimulant drugs and some hallucinogenic drugs can cause dilation of the pupil.[6]
In ophthalmology, intensive studies of pupillary response are conducted via videopupillometry.[7]
Anisocoria is the condition of one pupil being more dilated than the other.
| Constriction | Dilation | |
|---|---|---|
| Muscular mechanism | Relaxation of iris dilator muscle | Activation of iris dilator muscle |
| Cause in pupillary light reflex | Increased light | Decreased light |
| Other physiological causes | Fight-or-flight response | |
| Corresponding non-physiological state | Miosis | Mydriasis |
[edit] See also
- Dilated fundus examination
- Iris dilator muscle
- Iris sphincter muscle
- Mydriasis
- Miosis
- Pupillary light reflex
- Pupillometry
- Pupilometer
[edit] References
- ^ Ellis CJ (November 1981). "The pupillary light reflex in normal subjects". Br J Ophthalmol 65 (11): 754–9. doi:10.1136/bjo.65.11.754. PMC 1039657. PMID 7326222. http://bjo.bmj.com/content/65/11/754.full.pdf.
- ^ Hess, Eckhard H.; Polt, James M. (5 August 1960), "Pupil Size as Related to Interest Value of Visual Stimuli", Science 132 (3423): 349–50, doi:10.1126/science.132.3423.349, PMID 14401489
- ^ Lowenstein, Otto; Feinberg, Richard; Loewenfeld, Irene E. (April 1963), "Pupillary Movements During Acute and Chronic Fatigue: A New Test for the Objective Evaluation of Tiredness", Investigative Ophthalmology (St. Louis: C.V. Mosby Company) 2 (2): 138–157, http://www.faa.gov/library/reports/medical/oamtechreports/1960s/media/AM65-09.pdf
- ^ Baker, Lynn Erland (1938). The Pupillary Response Conditioned to Subliminal Auditory Stimuli. Ohio State University. http://www.worldcat.org/title/pupillary-response-conditioned-to-subliminal-auditory-stimuli/oclc/6894644.
- ^ Podolak, Edward; Feinberg, Richard (September 1965) ([dead link]), Latency of pupillary reflex to light stimulation and its relationship to aging, Federal Aviation Agency, Office of Aviation Medicine, Georgetown Clinical Research Institute, p. 12, OCLC 84657376, http://www.faa.gov/library/reports/medical/oamtechreports/1960s/media/AM65-25.pdf
- ^ Jaanus SD (1992), "Ocular side effects of selected systemic drugs", Optom Clin 2 (4): 73–96, PMID 1363080
- ^ Ishikawa, S.; Naito, M.; Inaba, K. (1970), "A new videopupillography", Ophthalmologica 160 (4): 248–259, doi:10.1159/000305996, PMID 5439164
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