Fig. 32. Deep sclerectomy with viscocanalostomy: identification of Schlemm's canal with a suture probe. Canal identification is aided by inserting a thermally blunted (A) 5-0 clear nylon suture into the proposed canal site (B). There are three possible locations the suture may traverse: properly into the canal, posteriorly into the supraciliary space, or anteriorly into the anterior chamber. Even though the distal suture end is hidden from view, verification of canal identity is made by flexing the suture. Flex the suture anteriorly (C) and release. On release, the suture should bounce back to its original position if secured properly in the canal. If the suture stays flexed anteriorly, it is likely in the supraciliary space. If the suture is mistakenly in the anterior chamber, posterior flexion over the sclera (D) will cause the distal end to migrate into the anterior chamber, an obvious sign of malposition. Anterior and posterior flexion with immediate return to the original position is a good sign the probe is in the canal.