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By analogy with a camera, the pupil is equivalent to aperture, whereas the iris is equivalent to the diaphragm. It may be helpful to consider the Pupillary reflex as an 'Iris' reflex, as the iris sphincter and dilator muscles are what can be seen responding to ambient light. [2] Whereas, the pupil is the passive opening formed by the active iris.
Dilation and constriction of the pupil Pupillary response is a physiological response that varies the size of the pupil between 1.5 mm and 8 mm, [ 1 ] via the optic and oculomotor cranial nerve. A constriction response ( miosis ), [ 2 ] is the narrowing of the pupil, which may be caused by scleral buckles or drugs such as opiates / opioids or ...
Although the pupillary response, in which the pupil dilates or constricts due to light is not usually called a "reflex", it is still usually considered a part of this topic. Adjustment to close-range vision is known as "the near response", while relaxation of the ciliary muscle to view distant objects is known as the "far response".
And when it’s bright, pupils shrink, protecting your eyes, which is why we are able to look at the sun with our naked eyes during daylight (though most of us don’t spend hours staring directly ...
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 Marcus Gunn pupil is a relative afferent pupillary defect indicating a decreased pupillary response to light in the affected eye. [3] In the swinging flashlight test, a light is alternately shone into the left and right eyes. A normal response would be equal constriction of both pupils, regardless of which eye the light is directed at.
Adie's pupil is caused by damage to peripheral pathways to the pupil (parasympathetic neurons in the ciliary ganglion that cause pupillary constriction to bright light and with near vision). The pathophysiologic mechanism which produces an Argyll Robertson pupil is unclear, but is believed to be the result of bilateral damage to the pretectal ...
Many photos Monday managed to catch a bright spot at the bottom of the eclipse. Murphy explained people were probably witnessing a "post eruptive solar prominence," which was likely the location ...