紫外线激发的角膜胶原交联术的动态安全

摘要

Objective To discuss the critical issues of the dynamics of UV-light-photoinitiated cross-linking in corneal collagen (CXL) and to confirm the dynamics of riboflavin (vitamin-B2) absorption under UV light.Methods Coupled dynamic equations are numerically solved and analytic formulas are derived for three critical parameters:the safe depth (z*),the safe dose (E*) and the cross-linking time (t*).Time-dependent absorption of UV light due to the depletion of the initiator is measured and shown by a dynamic spectrum of riboflavin.The critical issues of CXL are explored by seven parameters:the extinction coefficient,concentration,the penetration depth of the riboflavin,the UV light intensity and dose,irradiation duration,and corneal thickness.Results The safe dose (E*) has a wide range from 2.3 to 8.2 (J/cm2) for riboflavin concentrations of 0.1％ to 0.2％ and penetration depths of 0.02 to 0.04 cm.It is shown by mathematical modeling that a higher light intensity and extinction coefficient lead to shorter t* for a given cross-linking depth,while t* increases with corneal thickness (z*).The safety depth decreases as a function of the extinction coefficient and initiator concentration.Conclusion A new cross-linking protocol is suggested based on new findings,which include the safe depth (z*),the safe dose (E*),the cross-linking time (T*),and the safe riboflavin concentration.%目的 探讨紫外线引发角膜交联光动力学的关键问题,并以实验数据确认紫外线在核黄素内的吸收动力学理论.方法 耦合动力学方程的数值求解和分析公式推导出3个重要的参数:安全深度(z*),安全剂量(E*)和交联时间(T*).经由对时间函数的核黄素吸收系数实验测量,核黄素的动态频谱显示光敏剂随时间的耗竭.角膜交联光动力是由7个关键参数决定:核黄素(B2)的消光系数,浓度,光敏剂穿透深度,紫外线的强度和剂量,照射时间以及角膜厚度.结果 核黄素浓度范围为0.1％-0.2％,穿透深度范围为0.02～0.04 cm,安全剂量范围为2.3～8.2 J/cm2.我们的数学模式显示,较高的紫外线强度和消光系数导致较短的表面交联时间,而角膜厚度大的交联时间也增加.安全深度为消光系数和光敏剂浓度的反比函数.结论 基于我们的新的发现,角膜胶原交联术的动态安全参数包括安全深度,安全剂量,交联时间,和安全光敏剂浓度,我们提出一个新的交联临床规范.