An endoscopic surgical device having a slotted clear cannula, a blade and a housing, wherein the cannula is attached to the housing, and wherein the blade is enclosed in the housing and is slidable into the cannula is disclosed. The blade is enclosed within the housing and cannula, and has a horizontally-oriented pushing component and a vertically-oriented cutting component that protrudes through the slot of the cannula. The device further has a device for locking a viewing device in place relative to other components of the device. A method for a performing an operative procedure on a target tissue in a subject using the endoscopic surgical device is also described.