The visual perception of a lens wearer is not only along the gaze direction, but also has a non-zero transverse extension, which is called perceptual span. Perceptual span is skewed to extend further in the reading direction, i.e., the line portion to be read next relative to the line portion that was just read. A technique is provided that determines a pair of progressive ophthalmic lenses that take such perceptual span into account.