A small gauge mechanical tissue cutter/aspirator probe useful for removing the trabecular meshwork of a human eye has a generally cylindrical outer cannula, an inner cannula that reciprocates in the outer cannula, a port located near or at the distal end of the outer cannula on a side or tip of the outer cannula, and a guide with a distal surface located on the distal end of the outer cannula. A distance between the distal surface of the guide and the port is approximately equal to the distance between the back wall of Schlemm's canal and the trabecular meshwork.