| 摘要 |
A method of preparing a surface of refraction of a progressively variable power ophthalmic lens, in which a first family of surfaces S1 having predetermined optical characteristics is determined within a given system of rederence. Within the same system of reference a second family of surfaces S2 having other predetermined characteristics is determined, each surfaces S1 of the first family is associated with each surfaces S2 and their curves of intersection C and D are determined. Among the pairs of surfaces S1S2 is selected that one whose curves C and D provide therebetween a corridor respectively at least 15 and 18 mm wide in the intermediate vision zone Z2' and in the near vision zone Z3'. The refractive surface S of the ophthalmic lens is selected so as to have the part of the surface S of the selected pair which is between the curves C and D, and the part of the surface S2 of the selective pair which is outside curves C and D.
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