Laser ray tracing, a technique originally developed to measure ocular aberrations from the deviations of the local ray aberrations as a function of entry pupil, was used to assess cone directionality in 29 normal eyes (seven of which underwent LASIK surgery) and seven eyes after LASIK corneal refractive surgery for myopia. The total intensity of the retinal aerial images was computed as a function of the entry location of the illuminated beam. The measured intensity distribution was fit to a two-dimensional Gaussian function plus a constant background. The maximum of the distribution represents the pupillary location toward which the cone photoreceptors are oriented (peak of the optical Stiles–Crawford, SCE, function). We found the average SCE peak location was located mm nasally and mm inferiorly to the center of the pupil. In general, there was not a relation between the pupillary area of best quality and SCE peak location, either pre-operatively or post-operatively. The cone directionality shape factor was also unchanged by surgery. However, in two eyes, pre- and post-operative SCE peak location changed significantly. LASIK refractive surgery decreased the MTF in all eyes, even when the actual SCE directionality of the subject is considered. In the two eyes that showed significantly different SCE peak location, the apodized post-operative MTF with the post-operative SCE peak exceeded the simulated post-operative MTF assuming no shift in the SCE peak. However, the statistical power of these two cases is low, and the general findings are consistent with the hypothesis that differences in optical quality are not a major driving mechanism for cone orientation.

中文翻译：

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正常和 LASIK 患者激光光线追踪的锥体方向性


激光光线追踪是一种最初开发的技术，用于测量作为入瞳函数的局部光线像差偏差的眼像差，用于评估 29 只正常眼睛（其中 7 只接受了 LASIK 手术）和 7 只 LASIK 术后眼睛的锥体方向性角膜屈光手术治疗近视。视网膜航空图像的总强度被计算为照明光束的进入位置的函数。测量的强度分布适合二维高斯函数加上恒定的背景。分布的最大值代表视锥光感受器所朝向的瞳孔位置（光学 Stiles-Crawford、SCE、函数的峰值）。我们发现平均 SCE 峰值位置位于瞳孔中心鼻侧 毫米处和下方毫米处。一般来说，无论是术前还是术后，最佳质量瞳孔面积与 SCE 峰值位置之间都没有关系。手术后锥体方向性形状因子也没有改变。然而，在两只眼睛中，术前和术后 SCE 峰值位置发生显着变化。 LASIK 屈光手术降低了所有眼睛的 MTF，即使考虑受试者的实际 SCE 方向性也是如此。在显示出显着不同的 SCE 峰值位置的两只眼睛中，具有术后 SCE 峰值的变迹术后 MTF 超过了假设 SCE 峰值没有变化的模拟术后 MTF。然而，这两种情况的统计功效较低，总体结果与光学质量差异不是锥体取向的主要驱动机制的假设一致。