Atchison D A, Kris M, Sheedy J E, Bailey I L
Centre for Eye Research, Queensland University of Technology, Brisbane, Australia.
Optom Vis Sci. 1991 Apr;68(4):299-308. doi: 10.1097/00006324-199104000-00007.
Automated focimeters can be used to make quick, precise measurements of off-axis power and prismatic effects corresponding to an eye rotating behind a spectacle lens. An automated focimeter, the Humphrey Lens Analyzer, was assessed in this regard. The Humphrey Lens Analyzer can be used to give a valid measure of off-axis power of lenses with low power, but not of lenses with moderate to higher power (greater than 3 D). For 3 D spherical lenses discrepancies of the order of 0.1 D occur at 30 degrees rotation, and 6 D spheres give discrepancies of 0.5 D at the same rotation. Small discrepancies were found for measurements of prism. The Humphrey Lens Analyzer was also used in a mode where the lens being tested is rotated about the center of curvature of its back surface. This is the mode often used to assess aberrations and prism of progressive-addition lenses. In this mode, the instrument provides reasonable accuracy in estimating off-axis power corresponding to eye rotation for lenses with low power, but not for lenses with moderate to higher power (greater than 3 D). However, it provides accurate values of the variation in off-axis surface power for low powered lenses with aspheric front surfaces. There were considerable systematic errors associated with the measurement of prism. A simple raytracing method was developed to predict the results of measurements with the Humphrey Lens Analyzer. Predictions of off-axis power were good when lenses were rotated about a position corresponding to the center-of-rotation of an eye, but were poorer when lenses were rotated about the center of curvature of their back surfaces. Predictions of primatic efforts were good in both situations. A method by which the Humphrey Lens Analyzer should provide an accurate measurement of off-axis powers corresponding to eye rotation behind a spectacle lens is described, but has not been tested.
自动焦度计可用于快速、精确地测量与眼镜镜片后眼睛转动相对应的离轴屈光力和棱镜效应。本文评估了一种自动焦度计——汉弗莱镜片分析仪。汉弗莱镜片分析仪可有效测量低度数镜片的离轴屈光力，但无法测量中度至高度数（大于3D）镜片的离轴屈光力。对于3D球面镜片，在30度旋转时会出现约0.1D的偏差，而6D球面镜片在相同旋转角度下偏差为0.5D。棱镜测量中发现的偏差较小。汉弗莱镜片分析仪还可在一种模式下使用，即被测试镜片绕其后表面曲率中心旋转。这是常用于评估渐进多焦点镜片像差和棱镜的模式。在这种模式下，该仪器在估计低度数镜片眼睛旋转对应的离轴屈光力时提供合理的准确性，但对于中度至高度数（大于3D）镜片则不然。然而，对于具有非球面前表面的低度数镜片，它能提供离轴表面屈光力变化的准确值。棱镜测量存在相当大的系统误差。开发了一种简单的光线追迹方法来预测使用汉弗莱镜片分析仪的测量结果。当镜片绕与眼睛旋转中心对应的位置旋转时，离轴屈光力的预测效果良好，但当镜片绕其后表面曲率中心旋转时，预测效果较差。在两种情况下，棱镜效应的预测效果都很好。描述了一种方法，通过该方法汉弗莱镜片分析仪应能准确测量与眼镜镜片后眼睛旋转相对应的离轴屈光力，但尚未经过测试。
