Optical Aberrations Variations of the Human Eye During Accommodation

Abstract

Abstract: : Purpose: To study optical aberrations variation during accommodation in young healthy subjects. Methods: 28 eyes from 14 volunteers with spherical equivalent between –2D and +1D, no eye disease history and between 20 to 25 years–old, underwent wavefront measurements with a modified Shack–Hartmann wavefront sensor which included a moving accommodative target. Wavefront scans were repeated during 6 different decreasing accommodative stimuli going 5D to 1D with 0.5D steps during 2 seconds before and after pupil dilation with neosynephrin 5%. Measurements were repeated 3 times for each subject. Results: With accommodation, all aberrations increased (p<0.05). Monocularly, cylinder axis came closer to 90° as accomodation increased (p<0.05). Although vertical coma did not significantly vary with accommodation, horizontal coma increased significantly with accommodation (p<0.05). Spherical aberration changed from positive to negative value (p<0.05).<br /Conclusions: In this homogenous population effect of accommodation on optical aberrations is significant although balanced by pupil constriction during physiological accommodation. Optical quality of the eye is better without accommodation. The most significant variations of ocular aberrations during physiological accommodation seem to be appearance of with–the–rule astigmatism, consistant variation of coma and more negative value of spherical aberration.

Keywords: optical properties • astigmatism • visual acuity