Changes of the eye optics after iris constriction

• Main Authors: Robert Montés-Micó, Patricio Hernández, Vicente Fernández-Sánchez, Sergio Bonaque, Francisco Lara, Norberto López-Gil
• Format: Article
• Language: English
• Published: Elsevier 2010-10-01
• Series: Journal of Optometry
• Subjects: Iris; Ocular aberrations; Eye optics; Spherical aberration
• Online Access: http://www.sciencedirect.com/science/article/pii/S1888429610700315

Purpose: To evaluate the possible change in the optics of the human eye after iris constriction. Methods: Ocular aberrations were measured under natural viewing conditions in 26 eyes. The measured eyes fixated on a dim target while the contralateral eye was either occluded (so the measured eye had a large pupil) or highly illuminated (so the measured eye had a small pupil). The measured eyes fixated to a dim target placed 0.5 D beyond the subject’s far point. Zernike values obtained in both situations were compared within the same pupil diameter corresponding to the one obtained under the high illumination condition. Results: Significant variation in some aberration coefficients were found between the two illumination conditions. Specially, spherical aberration (SA) increased significantly after pupil miosis (P = .0017). The mean increase of SA measured was 0.018 microns, for a 3-mm pupil. Mean values of other ocular aberrations also vary significantly after pupil miosis (changes were larger than the standard deviation of the repeated measurements). A mean paraxial hyperopic shift of one third of diopter was found after iris constriction. Conclusion: Iris constriction slightly modifies the optics of the eye. The small hyperopic shift of the best image plane after iris constriction may be explained by a change in the lens shape and/or position.