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The reflex, controlled by the parasympathetic nervous system, involves three responses: pupil constriction, lens accommodation, and convergence. A near object (for example, a computer screen) subtends a large area in the visual field, i.e. the eyes receive light from wide angles. When moving focus from a distant to a near object, the eyes converge.
However, if the eyes are asymmetrically affected, i.e. one eye's optic nerve is more damaged than the other, it will produce an important sign called an afferent pupillary defect. [citation needed] Defective light perception in one eye causes an asymmetrical pupillary constriction reflex called the afferent pupillary defect (APD). [citation needed]
Scheme showing sympathetic and parasympathetic innervation of the pupil and sites of a lesion in Horner's syndrome. Horner's syndrome is usually acquired as a result of disease, but may also be congenital (inborn, associated with heterochromatic iris) or iatrogenic (caused by medical treatment). In rare cases, Horner's syndrome may be the ...
The Neurological Pupil index, or NPi, is an algorithm developed by NeurOptics, Inc., that removes subjectivity from the pupillary evaluation. A patient's pupil measurement (including variables such as size, latency, constriction velocity, dilation velocity, etc.) is obtained using a pupillometer, and the measurement is compared against a normative model of pupil reaction to light and ...
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 , [2] is the narrowing of the pupil, which may be caused by scleral buckles or drugs such as opiates/opioids or anti-hypertension medications.
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 ...
Normally, as part of the pupillary light reflex, the pupil dilates in the dark and constricts in the light to respectively improve vividity at night and to protect the retina from sunlight damage during the day. A mydriatic pupil will remain excessively large even in a bright environment. The excitation of the radial fibres of the iris which ...
The pupillary light reflex (PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity of light that falls on the retinal ganglion cells of the retina in the back of the eye, thereby assisting in adaptation of vision to various levels of lightness/darkness.