Fig. 29. Deep sclerectomy with viscocanalostomy: development of the deep scleral flap. A. Fashioning of the deep scleral flap is a near choroidal experience. The depth of the dissection is down to choroid, only sparing a few scleral fibers. Achieving this plane is critical to successfully unroof Schlemm's canal. If the flap is too superficial, Schlemm's canal will be passed over and the formation of the trabeculodescemetic membrane becomes much more difficult. If the plane is deep enough, Schlemm's canal will unroof as seen in (B), revealing the floor of the canal.