离焦与球差对人眼视锐度的交互影响

The reciprocal effects of defocus and spherical aberration on the visual acuity of human eyes

目的 探讨离焦和球差间的交互作用,分析离焦与球差单独或联合存在对人眼视锐度的影响.方法 实验研究.选取10名志愿者（10眼）,在暗室内麻痹睫状肌散瞳,应用自行研制的自适应光学高阶像差验配与视觉分析系统,在矫正人眼自身像差基础上,叠加不同程度和方向的离焦,测量志愿者在100％对比度下视锐度的变化;在叠加离焦的基础上,分别联合叠加正向及负向0.1 μm球差,测量视锐度.通过对叠加像差后视锐度变化作一元线性回归分析,得到视锐度随叠加像差变化的二项式拟合方程.结果 随着叠加的离焦量增加,10名志愿者视锐度逐渐下降;联合叠加同方向的球差后志愿者视锐度优于单独叠加离焦时视锐度;球差为0时,离焦在＋0.1 μm视锐度达到最大值;球差为＋0.1 μm时,离焦在＋0.3～＋0.5 μm之间,视锐度达到最大值;球差为-0.1 μm时,离焦为0,视锐度达到最大值.结论 球差与离焦之间存在相互影响,同方向球差增加了志愿者对于离焦的耐受.同向的离焦与球差共同存在,对视锐度的影响存在相互抵消的作用,较两者单独存在时对视锐度的影响更小.

Objective To analyze the interactive effects of defocus and spherical aberration on the visual acuity of human eyes, both individually and as a group.Methods Ten volunteer subjects were enrolled in this experimental study.After treatment to induce mydriasis and ciliary paralysis in a dark room, the subjects were tested for visual acuity at 100% contrast using a self-designed, adaptive, high-order aberration and visual analysis system.The visual acuity test was performed by adding different levels and directions of defocus after adjusting for the inherent aberration of each eye.Furthermore, we tested visual acuity by adding ＋/-0.1 μm of spherical aberration in combination with different levels of defocus.Using a single-element linear regression analysis for visual accuracy with the add-ons for aberration changes, we also obtained the representative binomial fitting equation.Results Visual acuity decreased with an increasing level of added defocus.However, visual acuity improved when the defocus was added in combination with spherical aberrations in the same direction.Based on our data, visual acuity reached a maximum value witb any of the following conditions： （1）spherical aberration=0 and defocus=＋0.1 μm, （2）spherical aberration=＋0.1 μm and defocus=＋0.3～＋0.5 μm, （3）spherical aberration=-0.1 μm and defocus=0 μm.Conclusion Spherical aberration and defocus reciprocally affect visual acuity.Spherical aberration in the same direction contributes to the tolerance of defocus.The co-presence of defocus and spherical aberration in the same direction produce less interference on visual acuity because of the counteractive effect between spherical aberration and defocus.