Charman W N
Am J Optom Physiol Opt. 1982 Dec;59(12):997-1001. doi: 10.1097/00006324-198212000-00011.
A concentric variation in sagittal power, Fs, with zonal radius, y, has been used in some designs of varifocal and aphakic spectacle lenses. It is shown theoretically, using a paraxial approximation, that a gradient dFs/dy in sagittal power leads to the introduction of an amount y.dFs/dy of unwanted astigmatism. The validity of this result is illustrated experimentally.
在一些变焦和无晶状体眼镜片的设计中，矢状面屈光力Fs随子午圈半径y呈同心变化。理论上表明，采用傍轴近似时，矢状面屈光力的梯度dFs/dy会导致引入量为y.dFs/dy的有害散光。通过实验说明了该结果的有效性。
