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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:
- 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
Last reviewed 01/2018