The invention relates to a method for determining an usage index value for an single-vision ophthalmic lens adapted to correct the vision of a myopic wearer. According to the invention the method comprises: an optical profile providing step S1 during which an optical profile of said ophthalmic lens is determined; a material profile providing step S2 during which a material profile of said ophthalmic lens is determined; a physical parameter determining step S3 during which at least one physical parameter among physical parameters of said optical profile and material profile is determined; a gain assessing step S4 during which at least two gains brought by at least one determined physical parameter is evaluated on at least one evaluation criterion of dissatisfaction of said wearer when wearing said ophthalmic lens; an usage index value determining step S5 during which a value of an usage index is determined by adding the assessed gain for the evaluation criteria.