Pupillary Light Reflex

Aka: Pupillary Light Reflex, Swinging Flashlight Test, Marcus Gunn Pupil, Direct Light Reflex, Consensual Light Reflex, Direct Light Pupillary Reflex Loss, Relative Afferent Pupillary Defect, Afferent Pupillary Defect, Pupil Reactivity

1. See Also
   1. Pupil Constriction (includes pupil reaction Neuroanatomy)
2. Indication
   1. Anisocoria (Unequal Pupils)
   2. Eye Neurologic Exam
3. Technique
   1. Check left eye response (direct and consensual)
      1. Shine light on left eye and check left pupil reflex
      2. Shine light on right eye and check left pupil reflex
   2. Check right eye response (direct and consensual)
      1. Shine light on right eye and check right pupil reflex
      2. Shine light on left eye and check right pupil reflex
4. Findings: Normal response
   1. Direct Light Reflex
      1. Pupil constricts to direct light
   2. Consensual Light Reflex
      1. Pupil constricts to light shining on opposite pupil
5. Findings: Abnormal - Afferent lesion (Marcus Gunn Pupil)
   1. Causes
      1. Retinal lesion
      2. Optic Nerve lesion
      3. Ischemic Optic Neuropathy
      4. Multiple Sclerosis
   2. Findings
      1. No pupil response to direct light
      2. Intact Consensual Light Reflex
         1. Paradoxical Pupil Dilation to direct light
         2. Occurs on moving light from opposite to affected eye
6. Findings: Abnormal - Efferent lesion (CN 3 or pupillary Muscle)
   1. Affected eye loses consensual and Direct Light Reflex
   2. Unaffected eye maintains consensual and direct reflex