Patent ID: 7887183
Filing Date: 2011-02-15
Classification: G02C

Abstract:
1. Method determining a progressive ophthalmic lens for a given wearer to whom a near-vision power addition (A) has been prescribed, the lens having a fitting cross marking the primary direction of view under wearing conditions, and a principal progression meridian between a far-vision zone and near-vision zone, the method comprising the steps of: measuring the lowering of view (V) of the wearer on a near-vision point aimed at; measuring a near-vision vertical horopter (H) as the angle made by the lowering of view (V) with a document containing the point aimed at, said document forming an angle (B) with the horizontal; measuring the near-vision elevation of the head (Hd) and/or the elevation of the eyes (E) of the wearer; determination of a near-vision vertical coefficient of participation of the head (Ptv determination of a progression length (PL) specific to the wearer, defined by the relationship PL=H(1−Ptf determination of the lens by optimization by optical calculation under wearing conditions, by using as target a power variation along the meridian with a progression length equal to said progression length specific to the wearer.