A vitreotomy device comprises a body extended by a cannula. The cannula has a closed distal end； it includes a window in its side wall close to said distal end. It houses a needle driven with reciprocating motion and capable of periodically closing said window. The device further comprises suction means connected to the needle, and a double-acting cylinder provided with a moving piston for controlling the movement of said needle. In said device, the needle is driven with reciprocating motion in translation in said cannula； said piston of the double-acting cylinder is secured directly to said needle； as a result, its movements enable the needle to be moved into a first position in which said needle closes said window, and a second position in which the needle leaves said window open. The device makes it possible to control very accurately the lengths of time for which the end of the cannula is open and closed.
