The human pupil ranges in size from 7.5–8 mm at full mydriasis to 1.5–2 mm at full miosis. This means that the area of the pupil (πr2), and thus the amount of light admitted to the eye, can vary by a factor of 36. At maximum constriction the fibers of the sphincter pupillae are shortened by 87% relative to their length in the resting state,201 a property possessed by no other smooth muscle in the human body.


Aqueous Humor Image Scale Pupil Size Aqueous Fluid Entrance Pupil 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Copyright information

© Springer-Verlag New York Inc. 1985

Authors and Affiliations

  • E. Alexandridis
    • 1
  1. 1.University Eye ClinicHeidelbergGermany

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