Why Are Tilt and Wrap Important?
If you wear prescription glasses, you know that changing the tilt of the lens changes the effective power of the lenses—they "see" differently. In fact, sometimes when adjusting the frame and adding additional or less tilt, a patient will say—"that's better", both from a comfort and from a visual point of view.
So, while the actual lens power doesn't change, the effect of tilt, either around the horizontal axis (pantoscopic tilt) or vertical axis (wrap angle) changes the effect of that lens for central and peripheral powers. Tilt changes the way the entire lens "sees."