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Dilation and constriction of the pupil. Pupillary response is a physiological response that varies the size of the pupil, via the optic and oculomotor cranial nerve.. A constriction response (), [1] is the narrowing of the pupil, which may be caused by scleral buckles or drugs such as opiates/opioids or anti-hypertension medications.
A mydriatic pupil will remain excessively large even in a bright environment. The excitation of the radial fibres of the iris which increases the pupillary aperture is referred to as a mydriasis. More generally, mydriasis also refers to the natural dilation of pupils, for instance in low light conditions or under sympathetic stimulation.
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.
When pupils are dilated, it means that they grow larger in size. This can happen for a number of different reasons, including drug use and arousal. 7 reasons why your pupils may be dilated, from ...
Opiate overdose symptoms and signs can be referred to as the "opioid toxidrome triad": decreased level of consciousness, pinpoint pupils and respiratory depression. Other symptoms include seizures and muscle spasms. Sometimes an opiate overdose can lead to such a decreased level of consciousness such that the person will not wake up.
The pupil diameter can vary greatly due to various factors (primarily the pupillary light reflex), from constriction to as small as 2 mm, to dilation larger than 8 mm in some individuals, though the maximal dilation also varies substantially by individual and decreases with age. The pupil gets wider in the dark and narrower in light.
Topical atropine is used as a cycloplegic, to temporarily paralyze the accommodation reflex, and as a mydriatic, to dilate the pupils. [15] Atropine degrades slowly, typically wearing off in 7 to 14 days, so it is generally used as a therapeutic mydriatic, whereas tropicamide (a shorter-acting cholinergic antagonist) or phenylephrine (an α-adrenergic agonist) is preferred as an aid to ...
Light of Other Days" is the title of a 1966 Hugo- and Nebula-nominated short story by Bob Shaw. It was incorporated into a novel in 1972, Other Days, Other Eyes, which also dealt with issues of surveillance and privacy. The title for both the novel and the short story is drawn from the poem "Light of Other Days" [2] by Thomas Moore.