Pupillary Light Reflex

Authors

Affiliations

Nathaniel Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Pupillary light reflex is a mechanism designed to prevent excess light from amaging the eye.

Anatomy

• CN II Optic n.
• nuclei:
• CN III Oculomotor n.

If you are shining a light in the left eye, then the L CN2 senses the light and sends afferents to the CN3 and CN3 sends efferents back to both right and left pupils to constrict

Testing

Shining light in one eye, you expect both eyes to have pupil constriction.

If both eyes have no change in pupil dilation, then this indicates either the ipsilateral CN2 or both CN3 are dysfunctional.

If only the ipsilateral eye constricts, than the contralateral CN3 is dysfunctional. If only the contralateral eye constricts, than the ipsilateral CN3 is dysfunctional