Checking pupils

When you check the pupils, look for changes in the pupil reaction, such as changes in the size of the pupils or the way they react to light. These changes may be signs of a head injury and need to be reported to your health professional.

When you check someone's pupils, look for changes from what is normal for that person. Some people's pupils are not normally equal in size or shape. This may occur after certain types of eye surgery. Use of some eye medications may also affect pupil size or the way the pupils react to light.

To check the pupils:

  • Look carefully at both eyes to compare the pupils' size and shape.
    • Look at the pupils in low light. The pupils will be naturally slightly larger (dilated) in low light.
    • Make sure the light is shining evenly in both eyes.
  • Use a flashlight or penlight to shine a beam of light in one eye at a time.
    • Each pupil should get smaller (constrict) when you shine the light in it.
    • The reaction should be the same on both sides (symmetric).
  • Note whether the pupils' reaction has changed since the last time they were checked.

Last Updated: July 9, 2008

related physicians

related services

Bon Secours International| Sisters of Bon Secours USA| Bon Secours Health System

This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Privacy Policy. How this information was developed to help you make better health decisions.

© 1995-2010 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.