测量接触镜近轴后顶焦距可行性分析

主要论述了由焦度仪测量的接触镜实际后顶焦距转化为近轴后顶焦距的可行性问题以及近轴后顶焦距与实际应用相适应性的问题。通过分析和比对一些厂家生产的接触镜光学结构参量 r,n,d后认为 ,由于接触镜球差较大 ,而球差由光学结构参量确定 ,因而同一近轴后顶焦距不同 ,光学结构参量的接触镜实测后顶焦距也不同 ,并且偏差超出了允许范围。所以实际后顶焦距转化为近轴后顶焦距是不恰当的。同时近轴后顶焦距的倒数表征的光焦度与临床验光给出的实际光焦度意义不同 ,因而定义与实际应用不相适应。作者最后提出了接触镜后顶光焦度定义的修正建议

Analysis of feasibility for paraxial back vertex length of contact lens

This article mainly elucidates the feasibility of the real back vertex focal length which is measured by focometer transformed into paraxial back vertex focal length, and the adaptability of paraxial back vertex focal length and its practical application After comparing and analyzing the optical structure parameters (r,n,d) of contact lens that are manufactured by some factories, the writer finds it is not suitable to transform the real back vertex focal length into the paraxial back vertex focal length, because the spherical aberration of contact lens is bigger and the spherical aberration is defined by its optical structure parameters When the lens has same paraxial back vertex focal length and different optical structure parameters, their real measurements value of back vertex focal length are different, and the deviation is beyond the permitted scope On the other hand, the diopter defined by the reciprocal of the paraxial value of the back vertex focal length is not the real one got from clinical optometry So the definition is not adaptable to the application At the end of the article, the writer submits the amendment of definition of back vertex power