The blade is turned horizontally and the incision continued posteriorly until the insertion of the uncinate process is reached. If this incision is properly placed, it provides accurate margins for the correctly sized bony ostium and for complete exposure of the lacrimal sac. A 30° endoscope can be employed so that the view captures the lateral nasal wall. The endoscope is pushed high into the nasal vestibule and all instruments are passed under the endoscope. At no time should the endoscope and instruments cross.

A suction Freer is used to elevate the mucosal flap, making sure that the tip of the Freer is on bone at all times during this process (Fig. 11.1b). The frontal process is rounded and its posterior aspect falls away, and if care is not taken to maintain contact between the bone and the elevator the surgical plane will be lost. The 30° endoscope allows the tip of the Freer to be visualized as the dissection proceeds around the frontal process of the maxilla toward the insertion of the uncinate. The flap is elevated up to the insertion of the uncinate but no further. The thin lacrimal bone is sought between the insertion of the uncinate and the posterior aspect (otology instrument from ear instrument set) of the frontal process of the maxilla. A round blade is used to palpate the hard bone of the frontal process of the maxilla until the soft lacrimal bone is clearly identified. This palpation is best done in the region directly above the insertion of the inferior turbinate into the lateral nasal wall in the inferior aspect of the raised flap. The round blade is used to elevate the thin lacrimal bone over the posterior inferior aspect of the lacrimal sac. This allows the forward biting Hajek Koefler punch (Karl Storz, Tutlingham, Germany) to be inserted. The tip of this instrument is placed on the exposed sac where the lacrimal bone had been removed and as the instrument is engaged, the tip pushes the lacrimal sac away and allows the bone over the anterior inferior aspect of the lacrimal sac to be removed (Fig. 11.2a).

Removal of bone is continued superiorly until the punch can no longer be seated. At this point (about half way up toward the superior incision) the bone becomes too thick for the punch to be able to grip. A powered 25° endoscopic DCR burr is attached to a microdebrider handpiece (Medtronic Xomed, Jacksonville, FL, USA) and used to remove the residual bone covering the lacrimal sac (Fig. 11.2b).

First, the residual bone exposed by elevation of the flap is thinned. Once the bone is thin, then the burr is moved to the bone–lacrimal sac junction and the remaining lacrimal sac is exposed. Care should be taken not to push the burr too far under the edge of the bone as this creates significant pressure on the lacrimal sac and the burr will create a hole in the sac. However, the sac wall is able to withstand light pressure as long as the entire burr can be visualized during the dissection. As the bone is removed in the region of the posterior superior sac, the underlying mucosa of the agger nasi cell is exposed. This is routinely done as the superior portion of the lacrimal sac is constantly related to the agger nasi cell. In addition a small amount of skin is routinely exposed just anterior to lacrimal sac indicating complete bony removal and defining the anterior aspect of the lacrimal sac. Once the bony removal is complete, the lacrimal sac should stand proud of the lateral nasal wall (Fig. 11.2c). This allows the sac to be completely marsupialized into the lateral nasal wall. A Bowman’s lacrimal probe is placed into the lacrimal sac and the medial wall of the sac is tented (Fig. 11.3).

The tip of the probe should be clearly visualized before incision of the sac is attempted. If the tip of the probe is at the common canaliculus entry to the sac, it may appear as if the probe is in the sac, as the sac will still move when the probe is moved. Incision in this scenario can potentially injure the common canaliculus’ opening into the sac. The sac is opened using a DCR spear knife (Medtronic Xomed, Jacksonville, FL, USA). The knife is introduced into the sac lumen directly under the tip of the probe and the sac opened by rotating the spear knife (Fig. 11.4a). Do not insert the whole blade into the sac lumen, rather only the cutting edge. The sac is opened from top to bottom. The DCR mini-sickle knife (Medtronic Xomed, Jacksonville, FL, USA) is used to create releasing incision at the superior and inferior extent of the vertical incision allowing the anterior lacrimal mucosal flap to be rolled anteriorly toward the anterior nasal mucosal incision (Fig. 11.4b). Microscissors are used to make posterior releasing incisions at the top and bottom of the vertical incision. This allows the posterior lacrimal flap to be rolled posteriorly with complete marsupialization of the lacrimal sac. A standard sickle knife is used to make a vertical incision into the mucosa of the agger nasi cell and to roll this mucosa anteriorly until it meets the mucosa of the posterior lacrimal flap with mucosa-to-mucosa apposition. The original nasal mucosal flap is trimmed with pediatric through-biting forceps creating a superior limb of mucosa the same size as the space between the superior incision and the lacrimal mucosa (Fig. 11.5).

In addition the nasal mucosa is trimmed until it approximates the posterior lacrimal flap. An inferior limb can also be created if there is a space between the lower portion of the opened lacrimal sac and the inferior incision. This should allow approximation of nasal mucosa and lacrimal mucosa superiorly, posteriorly, and inferiorly. The only area where lacrimal and nasal mucosa will usually not be approximated is the anteriorly where the anterior lacrimal mucosa will often fall a few millimeters short of the anterior incision. If the common canaliculus grips the Bowman’s canaliculi probe tightly, it is assumed that there is tightness of the valve of Rosenmuller. In these circumstances silastic O’Donaghue lacrimal intubation tubes are placed through the upper and lower canaliculus into the nose. These tubes are left for 4 weeks before removal. This dilates the valve of Rosenmuller allowing freer drainage of tears from the conjunctiva to the nose. If the Bowman’s probe is loose in the valve then silastic tubes are not placed. If silastic tubes are placed, a 4 mm silastic tube cut to 0.5 cm is slid over the O’Donaghue tubes to act as a spacer (Fig. 11.6a). A loop of silastic tubing is pulled in the medial canthal region to ensure that there is no tension on the tubing. If the tubes are tight, they can cheese wire through the superior and inferior puncta. Once the silastic tubing is tension free, Liga clips^® are placed endoscopically behind the silastic spacer. A rectangular piece of Gelfoam^® (Pharmacia & Upjohn, Kalamazoo, MI, USA) is slid up the tubes onto the lacrimal mucosa. The silastic tubes are cut. Gelfoam^® is lifted and the position of the flaps verified before the Gelfoam^® is replaced (Fig. 11.6b). The operation is complete.