Objective: To analyze the aberration properties of contact lens and its central back vertexpower measurement.
目的：探讨接触镜的球差特征以及后顶焦距测量的实质。
2
Objective:To confirm that the lensometer adjusted by the special lenses group for contact lenses can't express the back vertexpower of contact lenses.
目的：证实采用接触镜专用标准透镜组标定的焦度计不能准确测定被测角膜接触镜的顶焦度。
3
This paper describes the error in focimeters, the principle of selection on curvature of inside face for vertexpower of standard lenses and the method for measuring them.