Marcus Gunn pupil


In Marcus Gunn pupil there is relative weakness of which of the following pathway –


A. Afferent limb of accommodation reflex

B. Efferent limb of accommodation reflex

C. Afferent limb of the pupillary light reflex

D. Efferent limb of the pupillary light reflex



Marcus Gunn pupil-


There is relative weakness of the afferent limb of the pupillary light reflex compared to the other eye

When light is rapidly transferred from the normal eye to the eye with Marcus Gunn pupil , the Marcus Gunn pupil dilates instead of constricting.

Also called as – Relative afferent pupillary defect (RAPD)


Direct light reflex


When a bright light is shone on one eye, its pupil constricts. This pupillary constriction is known as a direct light reflex.


Consensual light reflex


When a bright light is shone on one eye, its pupil constricts. This pupillary constriction is known as a direct light reflex. Simultaneously, the pupil of the other eye also constricts. This response in the contralateral eye is known as a consensual light reflex.


What are the Tests to Identify and Quantify RAPD?


  1. Gunn test
  2. Kestenbaum-Gunn test / modified Gunn test
  3. Swinging flashlight test
  4. Pupillography

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