ABSTRACT
Historical review of nonpenetrating filtering surgery In 1962 Kraznov performed the first sinusotomy. This operation consisted of removing a lamellar band of the sclera and opening Schlemm’s canal over 120° from 10 to 2 o’clock (Fig. 2.1).1-4 The inner wall of Schlemm’s canal was untouched and then the conjunctiva was closed. Kraznov believed that the aqueous outflow resistance in most cases of primary open-angle glaucoma was situated at the level of scleral aqueous-drainage veins and not in the trabeculum. He therefore developed a safe non-penetrating filtering surgery, leaving in place the trabeculum and the inner wall of Schlemm’s canal. When there was no percolation of aqueous through the trabeculum and Schlemm’s canal inner wall, Kraznov entered the anterior chamber and performed a peripheral iridectomy, creating a full-thickness procedure that was the standard filtering surgery at that time. Sinusotomy was definitely safer than full thickness surgery with almost no postoperative complication, which was certainly not the case with standard fullthickness procedures frequently leading to a major hypotony, followed in many cases by a flat anterior chamber, choroidal detachments, and cataract formation. Kraznov also reported
Figure 2.1 Schematic representation of sinusotomy Schlemm’s canal is unroofed. There is no superficial scleral flap to cover the sclerectomy. Inner wall of Schlemm’s canal is untouched.
