Abstract: Disclosed are a method and device for manufacturing an ophthalmic lens for eyeglasses intended to be placed in front of an eye of a wearer, the ophthalmic lens having a desired optical function including a dioptric function adapted to a prescription of the wearer. The method includes: providing an optical element made of a first material having a first refractive index, the optical element being intended to be modified to manufacture the ophthalmic lens; providing data relative to the modification of the optical element enabling to obtain the desired optical function; determining at least one zone in the first material based on data; and modifying the refractive index of the first material to form a pattern in the determined zone with focused femtosecond laser pulses according to data so as to obtain an ophthalmic lens having the desired optical function.