Abstract: A surgical knife blade for forming an incision of predetermined length in bodily tissue includes indicia disposed adjacent opposing portions of a cutting edge such that alignment of the opposing indicia with the tissue during insertion of the knife blade in the tissue produces an incision of the predetermined length. A method of performing cataract surgery utilizes the surgical knife blade to precisely form a smaller incision for lens removal and a larger incision for implant of the intraocular lens.

Abstract: A scalpel includes a blade carrier and blade shield equally movable but in opposite longitudinal directions in response to longitudinal movement of an actuator along the upper edge of the scalpel housing. Equal and opposite motion is achieved using a pinion disposed in the housing and engaged on opposite diametric sides by racks secured to the blade shield and blade carrier. The actuator is compressible to remove stop members secured thereto from respective recesses, thereby permitting movement of the blade carrier and blade shield from defined extreme positions.