Premium
AN ANALYSIS OF THE FORCES DETERMINING THE SIZE OF THE PUPIL
Author(s) -
DAVANGER MARTIN
Publication year - 1972
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.1972.tb03776.x
Subject(s) - caliber , pupil , mechanics , rest (music) , sphincter , tension (geology) , mathematics , physics , classical mechanics , anatomy , optics , materials science , medicine , acoustics , metallurgy , moment (physics)
The constricting effect of sphincter, and the dilating effect of dilatator, vary inversely proportionally to the size of the pupil. The forces of dilatator and sphincter, which determine the size of the pupil, may be considered as analogous to the forces determining the caliber of a cylindrical elastic vessel, namely the pressure in the vessel and the tension of its wall. The equation S=d · r is analogous to the law of Laplace T=P · r. The pupil is at rest when the force of dilatator is 2π times the force of sphincter. This relationship is the condition of equilibrium. If from a state of equilibrium the force of one or both muscles is changed, the pupil contracts or dilates until the condition of equilibrium, as stated above, is again established.