Effects of spherical aberration on visual acuity at different contrasts
Received 19 November 2008; received in revised form 4 March 2009; accepted 18 March 2009.
Purpose
To evaluate the effect of spherical aberration on visual acuity by correcting and inducing spherical aberration using an adaptive optics vision simulator.
Setting
Laboratory of Vision Science, Capital Medical University, Beijing, and Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu, China.
Methods
An adaptive optics vision simulator comprising a wavefront sensor and a 37-segmented deformable mirror was used to correct and induce aberrations of the eye. The effective ocular wavefront aberration was manipulated with the deformable mirror, as the resulting visual performance was simultaneously measured. Subjective visual acuity measurements were performed with a 6.0 mm pupil. Visual acuity at different contrasts was measured when spherical aberration was fully corrected and the other natural aberrations in the eye were present and when spherical aberration values were induced with the other aberrations corrected.
Results
The natural root-mean-square (RMS) value of spherical aberration in the 8 subjects examined was between −0.11 μm and 0.14 μm. There was no significant improvement in visual acuity with spherical aberration corrected and the subjects' natural aberrations present. When all aberrations were corrected, a decrease in visual acuity occurred when spherical aberration RMS was induced at 0.2 μm and 0.3 μm.
Conclusions
When fluctuation of other natural aberrations in the eye were present, there was a slight effect on visual acuity when the spherical aberration RMS was approximately 0.1 μm. Therefore, an RMS value of 0.1 μm could be an acceptable amount of spherical aberration when correcting spherical aberrations.
From Beijing Tongren Eye Center (J. Li, Xiong, Wang, S. Li), Beijing Tongren Hospital, Capital Medical University, Beijing, and Institute of Optics and Electronics (Dai, Xue, Zhao, Jiang, Zhang), Chinese Academy of Sciences, Chengdu, China
Corresponding author: Ningli Wang, MD, PhD, Beijing Tongren Hospital, Capital Medical University, Beijing Tongren Eye Center, Dongjiaomin Lane 1, Dongcheng District, Beijing 100730, China.
Jing Li, MD, and Ying Xiong, MD, PhD, contributed equally to this work.
No author has a financial or proprietary interest in any material or method mentioned.
Presented in part at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, Chicago, Illinois, April 2008.
Supported by a grant (60438030) from National Natural Science Foundation of China and the National “863” Program of China (2006AA02Z4D2).
Drs. Orla Casey and Michael Morgan critically read the manuscript.
ABSTRACT