Cranial Nerves – Pulpillary Light Reflex
020-pul

Pulpillary Light Reflex (PLR)

• Function
  This reflex requires a number of pathways to be intact. These include CN II, the brain stem [pretectal nuclei, Parasympathetic (PS) nucleus of CN III], and PS fibers of CN III
• Assessment
  A strong light source must be used. The light is shined into the patient’s eye and the pupillary response is observed. In a normal response the eye which the light is shined has pupillary constriction (direct reflex) AND the contralateral pupil also constricts (indirect or consensual reflex). An abnormal response (no pupillary constriction) can help to localize the lesion, particularly when interpreted with the result of vision testing.
While observing the pupillary light response one should also check that the pupils are the same size.
 
• See figure 6