Patent ID: 7887183

Claim:
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 nv =Hd(V+B); determination of a progression length (PL) specific to the wearer, defined by the relationship PL=H(1−Ptf nv ), the progression length being defined as the angle of lowering of the eyes between the fitting cross (FC) and the point of the meridian for which the power reached the power addition (A); 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.