Abstract: The invention generally relates to medicine, but more particularly, to an strument for making corneal incisions useful, for example, in the surgical treatment of myopia.The instrument disclosed herein includes a case, a holder of a cutting member being mounted within the case for reciprocation relative thereto. The holder is provided with a lock member for a cutting member at one end thereof, its opposite end accommodating a stem engaging a screwnut type drive urging said holder into motion. A stop is mounted on the case anteriorly relative to said holder. According to the invention, the portion of the holder facing the stop which is rectangular in cross-section, is preferably provided with a rectangularly fashioned groove along with a lever clip mounted therein, to secure the cutting member in position.