Fig. 28. Deep sclerectomy with viscocanalostomy: outlining the deep scleral flap. There are several nuances related to outlining the deep flap. The incision is made in the scleral bed (white arrows), approximately 1 mm from the border of the bed. The depth of the incision should be down to but not touching choroid. As the limbus is approached, caution is needed to prevent entering the anterior chamber. However, the depth of the incision should be kept constant as the limbus is approached to facilitate a clean dissection of the deep flap up to and beyond Schlemm's canal. If the incision is made too close to the border of the bed, postoperative fibrosis is more likely to seal the ostia of Schlemm's canal.