个性化人眼模型及屈光手术视觉质量评估

人眼是一台精巧而复杂的光学成像系统,其复合结构存在像差,它的空间极限分辨能力要小于无像差的同口径的小孔所对应的衍射极限。眼球也并非完美对称的,各介质曲面由于不规则性或位置异常等因素对视觉质量产生影响,为精确修正眼球的屈光不正带来困难。而常规的角膜手术虽然可以较好地修正以离焦为主的低阶像差,但却不能改善高阶像差,在手术实施的过程中反而会因为改变角膜的面型因子,引入较大的球差,严重影响暗视场的视力。本文依据人眼的基本结构及统计的典型人眼参数,实现全眼球数字化模拟并考虑了个性化因子,分析影响视力的主要因素,针对眼球屈光不正设计出个性化的角膜手术方案,使术后眼球的像差得到全面修正,从而实现最佳的人眼成像能力。

Customized human eye modelling and refractive surgery along with vision quality assessment

Background:Human eye is a complex and delicate imaging system, whose intrinsic optical aberrations limit the ultimate spatial resolution, making it worse than the diffraction limit of an aberration-free aperture in equal-size. Especially the asymmetry and irregularity presence in various components of eyeball would prevent the precise eye-surgery from achieving superb imaging quality. The conventional eye surgery could well correct the low-order optical aberrations dominant by "defocus", however make no rectification for the high-order aberrations. Meanwhile it would modify the original corneal a-sphericity to introduce significant "spherical aberration" to the eye-ball, which causes the severe reduction of vision acuity, especially at the dark environment.Purpose:In order to rectify the post-surgery visual quality reduction due to dimer environment, as well as the side-effects e.g. halo, dizziness, we proposed a personalized eye-modelling and surgery scheme, and compared the post-surgery outcomes to the conventional ones. Methods:We established a personalized eye model at the regular myopia of (?2D or?5D), and compared the post-surgery imaging quality of the conventional or customized corneal ablation schemes implementing three typical techniques in optometry: the ray-tracing spot diagrams at fovea, the modulation transfer function of the spot diagrams, and the wave-front aberration distributions of the eye-ball.Results:We find out that the traditional refractive surgery has many limitations, it can't correct the intraocular astigmatism and the high order aberrations either, while the customized eye surgery is able to reduce the various orders of the optical aberrations in general nicely to achieve the much better imaging quality. Conclusion:The techniques we use for assessing the imaging quality and spatial resolution at retina are objective, which clearly demonstrate the personalized eye-modelling and the ablation surgery schemes based on that achieved remarkable advantages to approach the retina resolution.