Objective:To confirm that the lensometer adjusted by the special lenses group for contact lenses can't express the back vertex power of contact lenses.
目的:证实采用接触镜专用标準透镜组标定的焦度计不能準确测定被测角膜接触镜的顶焦度。
This paper describes the error in focimeters, the principle of selection on curvature of inside face for vertex power of standard lenses and the method for measuring them.