pupillary light reflex
II Optic Nerve
Pupillary Light Reflex / Eyelid Elevation
Light entering the eye travels along the optic nerve
to the pretectal region of the mid brain to cause pupillary
constriction through the visceral motor and short ciliary
nerve components of the ocular motor nerve.
- observe for ptosis.
- observe the pupils for size (measure the diameter
of each pupil in mm).
- observe for any irregularities or asymmetry.
- dim the lights, ask the patient to look into the
distance, shine a bright light obliquely (approaching
laterally) into the pupil. Observe for the direct
response (same eye) and consensual response (opposite
- assess for an afferent pupillary defect (the swinging
flashlight test) by moving the light from one pupil
to the other, back and forth.
- to assess the accommodation reflex, ask the patient
to look in the distance and then at the tip of their
nose. (If the patient finds this manoeuvre difficult,
have them follow their extended thumb as it is brought
in towards the tip of their nose.)
- ptosis is present, if the eyelid covers part or
all of the pupil when looking directly ahead.