Fig. 8.13 Peeling of the inner wall of SchlemmÕs canal including the endothelium of SchlemmÕs canal and the juxta-canalicular trabeculum

Fig. 8.14 Suture of the collagen implant

Fig. 8.15 Closure of the superÞcial ßap with two stitches

8.1.3.6 Drainage Device

The initial and most important goal of deep sclerectomy has been achieved with the removal of both the inner wall of SchlemmÕs canal and the juxtacanalicular trabeculum, and the dissection of the DescemetÕs window. This step allows a gentle and continuous drop in the IOP, unlike what is seen with the penetrating procedure, such as trabeculectomy or insertion of the Seton tube where pressure can drop to zero. The second goal of the surgery is to maintain efÞcient Þltration through the DescemetÕs window and the trabeculum by preventing collapse of the superÞcial scleral ßap. It is crucial to keep the scleral space patent, a space where aqueous humor is collected before further routing into the intrascleral drainage pathways. Several devices may be used for this purpose. A cylindrical implant madeoflyophilizedporcinescleralcollagen(Aquaßow¨, Staar Surgical, Nidau, Switzerland), a triangular implant made of reticulated hyaluronic acid (SK gel¨, Allergan, Irvine, California, USA), a high-viscosity viscoelastics (Healon GV¨, Advanced Medical Optics, Inc., Santa Ana, California, USA), and a nonabsorbable drain made of highly hydrophilic acrylic (T-Flux¨, IOLTech, La Rochelle, France) have all been used with success [5, 6, 14Ð18]. The cylindrical collagen implant Aquaßow¨ is about 4 mm in length and about 0.5 mm in diameter in a dry state. The implant is placed radially onto the bed of the scleral space and secured with a nonresorbable 10-0 suture (Fig. 8.14). The proximal end of the implant is located next to the TDM. Upon insertion, the highly hydrophilic implant absorbs aqueous humor percolating from the trabeculum and the DescemetÕs window and swells to about twice its dry state size. This collagen implant is digested about 6Ð9 months after surgery.

8.1.3.7 Wound Closure

The superÞcial scleral ßap is repositioned into place, covering the space maintainer device, and a loose nonresorbable 10-0 suture is placed at each posterior corner of the ßap (Fig. 8.15). The stitch is tightened and the knot buried. Conjunctiva and TenonÕs layer are closed in two layers with a running resorbable 8-0 suture.