| 摘要 |
PROBLEM TO BE SOLVED: To provide the multifocal lens which is formed in consideration of the upper and lower preferable positions of the eye within the eye socket-and variation (decrease) in shortsightedness with the age. SOLUTION: A principal longitude part DP positioned in an intermediate sight distance area VI and a short sight area VP is divided into 1st section DC which is at an angleαto a perpendicular and a 2nd section CP which is at an angleωto the perpendicular. In this case, the value of the angleαis an increase function of an additional value A of the diopter of the lens and the angleωis smaller than the angleα. At the point C where those two sections meet each other, the mean spericity value of an aspherical surface A corresonds to a diopter additional value which is 0.8-0.92 time as large as the nominal diopter additional value of the lens.
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