The W-shaped pupil of the cuttlefish dilating when the<unk> s are turned off The<unk>  <unk>  or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity (luminance) of<unk>  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<unk> ness/darkness. A greater intensity of<unk>  causes the pupil to constrict (miosis/myosis; thereby allowing less<unk>  in), whereas a lower intensity of<unk>  causes the pupil to dilate (mydriasis, expansion; thereby allowing more<unk>  in). Thus, the<unk>  regulates the intensity of<unk>  entering the eye.<unk>  shone into one eye will cause both pupils to constrict.
Pupillary light reflex
Vestibulo–ocular reflex
Moro reflex
Corneal reflex
Oculocardiac reflex
Red reflex
Ocular tilt reaction
Galant reflex