It is an important test of brainstem function and the pupil will dilate if a person sees an object of interest.
1 If it dilates when light is shone on it, then this means that the light reflex is weaker than the consensual reflex (produced by withdrawing light from the unaffected eye), suggesting optic nerve pathology. 2  This abnormal response is known as a relative afferent pupillary defect (RAPD) and is a very important sign. There are essentially three reflexes to specifically test for: Light reflex test. 1  What it assesses-the integrity of the pupillary light reflex pathway. 2  How to perform it-dim the ambient light and ask the patient to fixate a distant target. 3  Illuminate the right eye from the right side and the left from the left side When this muscle contracts, it reduces the size of the pupil. This is the pupillary light reflex, which is an important test of brainstem function. Furthermore, the pupil will dilate if a person sees an object of interest. The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina. It appears black because light rays entering the pupil are either absorbed by the tissues inside the eye directly, or absorbed after diffuse reflections within the eye that mostly miss exiting the narrow pupil. A greater intensity of light causes the pupil to constrict (miosis/myosis) (allowing less light in), whereas a lower intensity of light causes the pupil to dilate (mydriasis, expansion) (allowing more light in). Thus, the pupillary light reflex regulates the intensity of light entering the eye. The pupillary light reflex pathway has an afferent limb (CN II) and efferent limb (CN III). The ganglion cells of the retina project bilaterally to the pretectal nuclei. The pupillary reflex pathway begins with the photosensitive retinal ganglion cells, which convey information to the optic nerve (via the optic disc). The optic nerve connects to the pretectal nucleus of the upper midbrain, bypassing the lateral geniculate nucleus and the primary visual cortex. The pupillary light reflex (PLR) is a reflex that controls the diameter of the pupil, in response to the intensity (luminance) of light that falls on the retinal ganglion cells of the eye, thereby assisting in adaptation to various levels of lightness/darkness. The pupillary reflex pathway begins with the photosensitive retinal ganglion cells, which convey information to the optic nerve (via the optic disc). The optic nerve connects to the pretectal nucleus of the upper midbrain, bypassing the lateral geniculate nucleus and the primary visual cortex. 1 What it assesses-the integrity of the pupillary light reflex pathway. 2  How to perform it-dim the ambient light and ask the patient to fixate a distant target. 3  Illuminate the right eye from the right side and the left from the left side. There are essentially three reflexes to specifically test for: Light reflex test. 1  What it assesses-the integrity of the pupillary light reflex pathway. 2  How to perform it-dim the ambient light and ask the patient to fixate a distant target. Follow Us On: A reflex is an involuntary motor response to a sensory stimulus. For example when a light shines into your eyes, your pupils should get smaller very quickly, or when there is a loud, sudden, unexpected sound nearby, you startle. Reflexes perform many jobs for our central nervous system.  Best Answer: The photopulipary reflex is important b/c it is the process of the iris contracting or expanding the pupil and controlling the amount of light entering the eye. 
http://patient.info/doctor/Pupillary-Abnormalities https://en.wikipedia.org/wiki/Pupillary https://en.wikipedia.org/wiki/Pupillary_light_reflex https://en.wikipedia.org/wiki/Pupillary_light_reflex http://patient.info/doctor/Pupillary-Abnormalities http://parentswithpurpose.com/the-importance-of-reflexes.html https://answers.yahoo.com/question/index?qid=20090303150904AADrXYM
what is a pupillary reflex important