The invention relates to a method for designing a pair of ophthalmic lenses and a device for optical measurements. The method comprises: determining a distance and placing an object (100) at said distance; placing a reference frame (4) on the user; for each eye: keeping it uncovered while covering the other eye; placing in front of the eye a screen (5, 6) with a through-opening (520, 620); shifting the position of the opening (520, 620) until the user sees said object (100) by looking through the opening (520, 620), so that said object (100) is centred in the available field of vision; uncovering the two eyes; adjusting the positions of the openings (520, 620) until achieving binocular vision; and designing each lens (510, 610) in accordance with said position. The device (1) comprises a frame (2) to which, for each eye, a first plate (51, 61) with a vertical slit (53, 63) and a second plate (52, 62) with a vertical slit (54, 64) are movably fastened. In this way, when the slits overlap, a stenopeic hole (55, 65) is formed.