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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/10/13 19:16:40」(JST)

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Miosis (or myosis, from Ancient Greek μύειν, mūein, "to close the eyes") is a term with various definitions, which generally include constriction of the pupil.

The opposite condition, mydriasis, is the dilation of the pupil. Anisocoria is the condition of one pupil being more dilated than the other.

Definitions

Definitions of miosis include:

Constriction of the pupil that is excessive,^[1] relative to the amount of light the pupil receives
Constriction of the pupil to a diameter of less than two millimeters^{[not in citation given]}^[2]^[3]
Constriction of the pupil with causes including both abnormal and physiological ones.^{[not in citation given]}^[4]
Pupillary constriction by abnormal causes.^{[not in citation given]}^[5]

Physiology of the photomotor reflex

Light entering the eye strikes three different photoreceptors in the retina: the familiar rods and cones used in image forming and the more newly discovered photosensitive ganglion cells. The ganglion cells give information about ambient light levels, and react sluggishly compared to the rods and cones. Signals from photosensitive ganglion cells have multiple functions including acute suppression of the hormone melatonin, entrainment of the body's circadian rhythms and regulation of the size of the pupil.

The retinal photoceptors convert light stimuli into electric impulses. Nerves involved in the resizing of the pupil connect to the pretectal nucleus of the high midbrain, bypassing the lateral geniculate nucleus and the primary visual cortex. From the pretectal nucleus neurons send axons to neurons of the Edinger-Westphal nucleus whose visceromotor axons run along both the left and right oculomotor nerves. Visceromotor nerve axons (which constitute a portion of cranial nerve III, along with the somatomotor portion derived from the Edinger-Westphal nucleus) synapse on ciliary ganglion neurons, whose parasympathetic axons innervate the iris sphincter muscle, producing miosis. This occurs because sympathetic activity from the ciliary ganglion is lost thus parasympathetics are not inhibited. Image

Causes

Age

senile miosis (a reduction in the size of a person's pupil in old age)

Diseases

Horner's syndrome
Hemorrhage into pons (intracranial hemorrhage)
Hereditary disorders
Cluster Headaches with ptosis
Iridocyclitis
Fatal familial insomnia

Drugs

Opioids such as fentanyl, morphine, heroin and methadone (the notable exception being demerol/pethidine)
Antipsychotics, including risperdal, haloperidol, thorazine, olanzapine, quetiapine and others
Cholinergic agents such as acetylcholine
Some cancer chemotherapy drugs, including camptothecin derivatives
Mirtazapine, a noradrenergic and specific serotonergic antidepressant (NaSSA)
Trazodone
Some MAO Inhibitors.
Pilocarpine Eye drops and all other parasympathomimetics
In some rare cases, when exposed to mustard gas.
Organophosphates

References

^ Farlex medical dictionary citing:
- Miller-Keane Encyclopedia & Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition.
- Saunders Comprehensive Veterinary Dictionary, 3 ed.
^ Seidel, Henry M.; Jane W. Ball; Joyce E. Dains; G. William Benedict (2006-03-29). Mosby's Guide to Physical Examination. Mosby. ISBN 978-0-32-303573-6.
^ Farlex medical dictionary citing: Millodot: Dictionary of Optometry and Visual Science, 7th edition.
^ Farlex medical dictionary citing: The American Heritage Medical Dictionary. Copyright 2007
^ Farlex medical dictionary citing: Mosby's Medical Dictionary, 8th edition.

External links

FP Notebook
-1254817782 at GPnotebook

UpToDate Contents

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1. 瞳孔不同患者へのアプローチ approach to the patient with anisocoria
2. 成人における急性オピオイド中毒 acute opioid intoxication in adults
3. 第二世代（非定型）抗精神病薬中毒 second generation atypical antipsychotic medication poisoning
4. ホルネル症候群 horner syndrome
5. 周術期に成人に静脈内投与するオピオイド鎮痛薬 perioperative uses of intravenous opioids in adults

English Journal

Accidental mushroom poisoning mimicking stroke. A case report and literature review.

Comelli I, Lippi G, De Blasio A, Cervellin G.Author information Emergency Department, University Hospital of Parma, Parma, Italy. gcervellin@ao.pr.it.AbstractWe describe here a paradigmatic case of mushroom poisoning mimicking a stroke. A 64-year old male was referred to the emergency department (ED) for a car accident. He was found diaphoretic, hypotensive, bradycardic, and slightly confused at presentation. No signs of trauma were observed on physical examination. The patient had weakness of the right limbs and bilateral severe myosis. The lab tests were normal, except for leukocytosis, mild hyperglycemia, mild hyperazotemia and moderate hypokalemia. The clinical picture, with the exception of miosis, was thereby suggestive for a stroke, which was also considered the cause of the car accident. The patients' wife, who was brought later to the ED, reported that the husband had suffered a stroke 4 years earlier, with residual right hemiparesis. She also referred that the patient showed signs of diaphoresis and confusion, and the car was intentionally driven into the ditch. Among other details, she referred that the husband ate mushrooms that she had personally collected 2 hours before taking the drive. Two mg of atropine, intravenous rehydration and potassium were hence administered in the suspicion of a cholinergic toxydrome, and complete clinical remission was rapidly obtained. Among the mixture of mushrooms eaten by the patient, a mycologist identified Armillaria Mellea (an edible mushroom) and notably Inocybe Fastigiata, a toxic muscarine-containing mushroom, easily confounded with Armillaria. After observation and oral rehydration, the patient was discharged.
Acta bio-medica : Atenei Parmensis.Acta Biomed.2014 Jan 23;84(3):229-33.
We describe here a paradigmatic case of mushroom poisoning mimicking a stroke. A 64-year old male was referred to the emergency department (ED) for a car accident. He was found diaphoretic, hypotensive, bradycardic, and slightly confused at presentation. No signs of trauma were observed on physical
PMID 24458168

Postcoital internal carotid artery dissection presenting as isolated painful horner syndrome: a case report.

Gozke E, Tastekin Toz H, Kahraman Koytak P, Alparslan F.Author information Department of Neurology, FSM Teaching and Research Hospital, 34752 Istanbul, Turkey.AbstractPostcoital artery dissection is a rare condition. Here we report a 40-year-old male patient with painful Horner syndrome related to postcoital internal carotid artery (ICA) dissection. In neurologic examination of the patient, semiptosis, enophthalmus, and myosis were observed on the left side. There were no carotid bruits. On T1-weighted and fat-suppressed cranial MRI, hyperintensity consistent with intramural hematoma was observed within cervical and temporal petrous segments of left ICA. On cervical and cranial MRA, marked decrease in the calibration of C1 and C2 segments of the left ICA was remarkable. The patient was diagnosed as left ICA dissection and anticoagulant therapy was initiated. A prominent improvement was noted in clinical findings during two months of followup period.
Case reports in neurological medicine.Case Rep Neurol Med.2013;2013:403647. doi: 10.1155/2013/403647. Epub 2013 Feb 28.
Postcoital artery dissection is a rare condition. Here we report a 40-year-old male patient with painful Horner syndrome related to postcoital internal carotid artery (ICA) dissection. In neurologic examination of the patient, semiptosis, enophthalmus, and myosis were observed on the left side. Ther
PMID 23533855

Intervention of laser periphery iridectomy to posterior iris bowing in high myopic eyes.

Wang HT, Wang NL, Li SN.Author information Capital Medical University, Beijing, China.AbstractBACKGROUND: For some high myopic patients with posterior iris bowing, laser periphery iridectomy should be performed pre-operation to prevent pupil block glaucoma if these patients would have phakic intraocular lens implantation to correct high myopia. So we had the opportunity to analysis the influence of laser iridectomy on posterior iris bowing.
Chinese medical journal.Chin Med J (Engl).2012 Dec;125(24):4466-9.
BACKGROUND: For some high myopic patients with posterior iris bowing, laser periphery iridectomy should be performed pre-operation to prevent pupil block glaucoma if these patients would have phakic intraocular lens implantation to correct high myopia. So we had the opportunity to analysis the influ
PMID 23253721

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