非接触式眼压计压平角膜过程的数值模型研究

通过采用双向流固耦合的数值仿真技术,建立了一个非接触式眼压计压平角膜过程的三维瞬态数值模型,研究了非接触式眼压计工作时角膜外流场的流动状态以及不同眼压角膜的动态变化过程,结果表明:非接触式眼压计的空气脉冲其流动基本满足射流理论,存在射流核心区、内外边界等特征;空气脉冲外边界角度为8.4°,不随时间变化,内边界角度从4.9°降至4.6°,随时间收窄;角膜压平时间随眼压增大而增大,而其压平直径基本不变,且压平直径为3.2~3.6mm时结果与有关文献中的非接触式眼压计压平直径数据一致。采用研制的模拟人眼配套的溯源装置对不同压平直径的情况进行实验,获得了压平直径过小将导致测量眼压偏大665Pa以上的结论,侧面验证了仿真结果的合理性。

Numerical Modelling of Non-contact Tonometer′s Cornea Applanation Process

A transient 3D fluid-structure interaction model of non-contact tonometer′s cornea applanation process has been built to study the external flow field of non-contact tonometer and the dynamic corneal deformation with different intraocular pressure. The results show that the flow field satisfies jet flow theory by showing certain characteristics like the potential core and outer jet boundary; the outer jet boundary of the non-contact tonometer air-puff is around 8.4° which does not change over time, while the jet core decrease from 4.9° to 4.6° over time; the applanation time of cornea increase with intraocular pressure while the applanation length remains in 3.2~3.6mm,which is consistent with the data on the applanation diameter of the non-contact tonometer in the relevant literature. Furthermore, an in-house made experimental device for phantom of intraocular pressure is used to compare results with different applanation length. The results show that comparatively small applanation length will cause severe deviation of intraocular pressure measurement up to 665Pa, which also matches with the simulation result.