A cam-guided trephine for selectively cutting a portion of an eye provides a first, vertically disposed blade to provide an annular cut of essentially any practical shape, diameter and depth, while concurrently allowing a second, angled blade, to simultaneously provide a circular cut of...http://www.google.fr/patents/US4423728?utm_source=gb-gplus-shareBrevet US4423728 - Cam-guided trephine
