examination (pupils)

Last reviewed 01/2018

Pupils should be circular, central and equal in size. They should constrict to light and accommodation equally.

There are four steps in the examination of the pupils:

  • inspection:
    • look for irregularity, inequality in size or eccentricity

  • light reaction:
    • with one eye shielded from a pen torch beam observe the constriction of the illuminated pupil (the direct response) and the constriction in the shielded pupil (the consensual response)

  • swinging light test:
    • the pen torch beam should be passed rapidly from one eye to the other
    • the normal response is sustained constriction of both pupils
    • if one pupil dilates upon illumination there is an relative afferent pupillary defect (Marcus Gunn pupil) in that eye
    • this is a simple test of optic nerve function

  • accomodation reflex:
    • the patient is asked to look at a distant object and then at an object close to his face
    • both pupils should constrict and dilate again when distant gaze is resumed