准分子激光眼屈光手术中的一种过渡区模型

提出了一种在准分子激光眼屈光手术中过渡区模型的构造方法.首先设计一种修边函数,然后提取光学区边界的切削深度,并将其扩展到整个过渡区,最后通过修边函数和过渡区上扩展切削深度的乘积得到过渡区模型.再将该模型进行计算机仿真研究和临床研究.临床上统计了8名患者16只眼睛接受该模型指导的激光手术情况:术前平均裸眼视力为0.09±0.04,术后第1天平均裸眼视力为1.06±0.24,之后视力逐渐升高,在术后一个月时平均裸眼视力为1.42±0.36,裸眼视力最小值为1.0.仿真结果,特别是临床结果表明:过渡区模型实现了光学区与非切削区之间光滑平坦地过渡.采用参数化控制的模型,特别适用于光学区直径和过渡区宽度经常调整的情况,对各种眼屈光不正情况均适用;在光学区直径确定后,过渡区宽度的改变不影响光学区的切削深度;模型有较强的通用性,适用于传统仅矫正屈光不正(近视、远视、散光)的光学区模型,也适用于波前像差引导的激光眼屈光手术.利用过渡区模型可提高手术后患眼的视觉质量.

Blend zone model for excimer laser refractive surgery

A blend zone model for excimer laser refractive surgery is presented. Firstly, a blend function is designed. Then, an expand ablation depth in the blend zone is constructed using the ablation depth on the edge of the optical zone. Finally, the model is developed by multiplying the blend function and the expand ablation depth. The simulation of the model on computer and results of clinical practice have been studied. Sixteen eyes with myopic astigmatism underwent LASIK using the blend zone model. One day postoperatively, mean uncorrected visual acuity was 1.06?0.24 compared to 0.09?0.04 preoperatively. One month after surgery, mean uncorrected visual acuity was 1.42?0.36. All eyes reached uncorrected visual acuity of 1.0 or better. The computer simulation and especially LASIK results show that the model gradually smoothes out the connection of the optical zone and untreated zone. The model has two parameters that make it very useful in adjusting the diameter of the optical zone and changing the width of the blend zone. The ablation depth in the optical zone does not increase when the width of the blend zone is changed. The model not only can be applied to the correction of refractive errors such as myopia and astigmatism, but also can be used in wavefront guided laser refractive surgery. Visual acuity after excimer laser refractive surgery has been remarkably improved using this model.