Patent ID: 7604350

Claim:
A method for calculating an ophthalmic lens, said ophthalmic lens comprising a first surface opposite the eye of a user, and a second surface orientated towards the user's eye, wherein said ophthalmic lens has a first power in its far vision area and a second power in its near vision area and characterized in that it comprises the following steps: a. calculating an initial lens from a given prescription, where said initial lens defines a first initial surface and a second initial surface; b. constructing a computational model of said initial lens; c. first plotting of a set of rays using said computational model; d. calculating an initial optical path traveled by each ray using said computational model, wherein said initial optical path is the sum of three sections, a first section before said first initial surface, a second section between said first initial surface and said second initial surface and a third section after said second initial surface; e. pre-selecting a first equivalent surface of an equivalent lens to said initial lens, wherein said first equivalent surface is selected from the group consisting of: a spherical surface and an aspherical surface, and has a power equal to the mean value between said first power and said second power; and f. calculating a second equivalent surface of said equivalent lens by means of the plotting of each ray through said equivalent lens and determining the point of intersection of each of said rays with said second equivalent surface, where, in order to determine the point of intersection with said second equivalent surface it is necessary that: each ray has an equivalent optical path equal to said initial optical path, or each of said rays has at least one of the sections of said equivalent optical path equal to the corresponding section of said initial optical path, so that said equivalent lens thus calculated is said ophthalmic lens.