激光老视术后调节的双因素理论(英文)

The two-component theory for accommodation after laser treatment of presbyopia

目的 :对于“激光老视治疗”的临床结果及基于弹性改变假说及晶状体前移及晶状体松弛模式的眼调节机制进行分析。方法 :根据光在模型眼中的传导原理 ,导出了总屈光力因晶状体与角膜屈光力、前房深度、眼轴长度及折射率而改变的函数。使用晶状体伸张及调节实验值导出与总屈光力变化相关的眼参数的实验方程。激光术后调节幅度使用林氏动态模型进行描述 ,此模型含晶状体的前移及松弛两个分量。同时提出林氏 卡达假说 ,认为术后调节改变及低回退率来自于巩膜 睫状肌弹性的增加。结果 :调节 (AA)幅度大约为晶状体屈光力改变的 73%～ 76 % ,并且与睫状体的收缩及晶状体厚度增加呈非线性变化。我们提出对于 2 .0D的调节可由晶状体松弛 (LR)或前移 (AS)或LR及AS两者组合而达到。对于硬化的老年晶状体 ,AS是主要因素。结论 :激光老视治疗 (LAPP)的临床结果可由光在眼球的传导方式计算及由弹性改变假说和包含晶状体前移和松弛的动态模型的调节机制来分析 ,其中动态模式包含晶状体前移及松弛两个因素。

Objective: To analyze the clinical results of the laser correction of presbyopia and the accommodation mechanisms based on the elasticity alteration hypothesis and the anterior-shift and lens-relaxation model.Methods: Using light propagation in an eye model,we derive the total refractive power changes as the function of lens-power,corneal-power,anterior chamber d e pth,globe axial length and the refractive indices of the lens,cornea and humor s. Experimental data of lens stretching and accommodation were used to derive so me semi-empirical equations for various eye parameters related to total power c h ange. The accommodation amplitude after a laser treatment is described by a two - component Lin dynamic mode given by the anterior shift and lens relaxation. We also propose the Lin-Kadambi hypothesis for the elasticity increasing of sclera -ciliary muscle complex for efficient accommodation and minimum regression.Results: The accommodation amplitude(AA),which is about(73% to 76%) of the l ens power change,has a non-linear response to the ciliary body contraction and to the lens thickness changes. We propose that the typical accommodation of 2.0 D after a laser procedure may be achieved by lens relaxation(LR) with radius cha nge or by anterior shift(AS) or by combining LR and AS,where AS is the dominat e contribution for aging lens with rigid lens capsule.Conclusion: Clinical results of laser presbyopia reversal(LAPR) may be analyze d by light propagation calculations and the accommodation mechanisms based on th e elasticity alteration hypothesis and the anterior-shift and lens-relaxation dynamic model.