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. 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. 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. The retinal photoceptors convert light stimuli into electric impulses. Pinpoint pupils (AKA small pupils) are exactly what they sound like: pupils that appear abnormally small (or below 2 mm) in normal lighting conditions. 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 ganglion cells give information about ambient light levels, and react sluggishly compared to the rods and cones. 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. In some rare cases, when exposed to mustard gas.Pilocarpine eye drops and all other parasympathomimetics.Mirtazapine, a noradrenergic and specific serotonergic antidepressant ( NaSSA).Some cancer chemotherapy drugs, including camptothecin derivatives.Serotonin antagonists, such as Ondansetron (an anti-emetic) known by its brand name Zofran.Cholinergic agents such as acetylcholine.In some cases, small pupils may indicate a drug overdose or other drug interaction. Antipsychotics, including risperidone, haloperidol, chlorpromazine, olanzapine, quetiapine Causes Other Reasons To Have Pinpoint Pupils Treatment Options Pinpoint pupil size may occur with the use of certain drugs such as heroin, morphine, fentanyl and other opioids.
Imidazolines such as clonidine, naphazoline, oxymetazoline and tetrahydrozoline.Products containing nicotine such as cigarettes, chewing tobacco or gum.Opioids such as fentanyl, morphine, heroin and methadone (the notable exception being pethidine).Hemorrhage into pons ( intracranial hemorrhage).Senile miosis (a reduction in the size of a person's pupil in old age).Anisocoria is the condition of one pupil being more dilated than the other. The opposite condition, mydriasis, is the dilation of the pupil. Miosis, or myosis (from Ancient Greek μύειν ( múein) 'to close the eyes'), is excessive constriction of the pupil.
0 kommentar(er)
