Miosis , or myosis , is excessive constriction of the pupil [1] [2] [3] [4] Ancient Greek μύειν mūein , "to close the eyes". The opposite condition, mydriasis , is the dilation of the pupil Anisocoria pupil being more dilated than the other.
原因 年齡 Senile miosis (a reduction in the size of a person's pupil in old age) 疾病 藥物 Opioid s such as fentanyl , morphine , heroin and methadone (the notable exception being pethidine )Products containing nicotine such as cigarettes, chewing tobacco or gum.
Imidazoline clonidine , naphazoline oxymetazoline tetrahydrozoline Antipsychotics , including risperidone , haloperidol , chlorpromazine , olanzapine , quetiapine and othersAntihistamines , such as diphenhydramine [5] Cholinergic acetylcholine Acetylcholinesterase inhibitors Serotonin antagonist Ondansetron (an anti-emetic) known by its brand name ZofranSome cancer chemotherapy drugs, including camptothecin derivatives
Mirtazapine , a noradrenergic and specific serotonergic antidepressant (NaSSA )Some MAO Inhibitors .
Pilocarpine eye drops and all other parasympathomimeticsIn some rare cases, when exposed to mustard gas
Organophosphates Physiology of the photomotor reflex Light entering the eye strikes three different photoreceptor s in the retina : the familiar rods and cones used in image forming and the more newly discovered photosensitive ganglion cell s. 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 circadian rhythm s 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 midbrain , bypassing the lateral geniculate nucleus visual cortex . From the pretectal nucleus neurons send axons to neurons of the Edinger-Westphal nucleus whose visceromotor oculomotor nerve s. 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 .
參見 參考資料 外部連結 Category:病征
Category:眼科
. Mosby. 2006-03-29. ISBN 978-0-323-03573-6.
. PMID 16722841. doi:10.1111/j.1365-2125.2006.02632.x.
