Each lens frame includes a slit at the assembly area of the corresponding temple, delimiting two independent which can be moved apart to widen the lens frame so that a lens can be inserted or removed. Each temple is connected to the corresponding lens frame by a tenon, including a first part connected to the temple, for making a rotating connection between the tenon and temple along the longitudinal axis of the temple, and a second pivotable part engaged between the portions of the lens frame. This second part, has a first dimension that can be in a first angular position of the tenon, in which the two portions, are not separated, and a second dimension in a second angular position of the tenon, in which the two portions are separated sufficiently to widen the lens frame so that the lens can be replaced.