A surgical tool for shearing tissue at a target surgical site, the surgical tool comprising a cannula assembly, a cannula opening into the lumen of the cannula assembly at a distal end, a cutting device coupled to the distal end and within the cannula opening, and an axial ball joint coupled to the proximal end of the cannula assembly, that when rotated, causes the cutting device to rotate about a longitudinal axis passing axially through the lumen of the cannula assembly, so as to shear a portion of tissue at a target surgical site. The target surgical site is a trabecular meshwork of an eye for treating glaucoma in a subject. Also disclosed is a surgical tool for shearing tissue comprising a cannula assembly with a flexible sheath attached to a cannula hub comprising a central inner hub hole and one or more outer hub holes coupled to the cannula assembly.
