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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.
For an adequate test, vision must not be entirely lost. In dim room light, the examiner notes the size of the pupils. The patient is asked to gaze into the distance, and the examiner swings the beam of a penlight back and forth from one pupil to the other, and observes the size of pupils and reaction in the eye that is lit.
The pupillary reflex results in the pupil constricting (left) and dilating (right) These include the pupillary light reflex and accommodation reflex . 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.
[clarification needed] The fixation sites are located in the midperiphery of the iris, which is immobile during pupillary movement. The original biconvex lens design was modified into a convex-concave design, [ 1 ] and manufactured as Artisan/Verisyse lens and later the foldable model (Artiflex), a three-piece lens with silicone optic and PMMA ...
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.
The ability of the rodless, coneless mice to retain a pupillary light reflex was suggestive of an additional photoreceptor cell. [11] In the 1980s, research in rod- and cone-deficient rats showed regulation of dopamine in the retina, a known neuromodulator for light adaptation and photoentrainment. [3]
Pupillary reflexes, particularly the pupillary light reflex, are a powerful diagnostic tool often employed in clinical and emergency medical practice. A lack of equal consensual pupillary constriction to a light stimulus, especially a Marcus Gunn pupil, can be indicative of optic nerve damage, brainstem death, or optic tract damage in between.
Pupils of both sexes dilated after seeing pictures of people of the opposite sex. In females, the difference in pupil size occurred also after seeing pictures of babies and mothers with babies. This examination showed that pupils react not only to the changes of intensity of light (pupillary light reflex) but also reflect arousal or emotions.