Canalicular stenosis is the most common indication for endoscopic CDCR. This blockage may be secondary to trauma, prior surgery, systemic chemotherapeutic agents such as Taxotere or 5-FU, or chronic use of topical ophthalmic medications that can cause a low-grade or high-grade allergic conjunctivitis. Unicanalicular or bicanalicular blockage, in addition to significant common canalicular stenosis, can cause epiphora.

When any type of canalicular stenosis is identified, treatment can involve silastic intubation. Often, monocanalicular intubation is performed. If this treatment fails to eliminate the symptoms, then endoscopic CDCR should be considered. When canalicular stenosis is present, dacryocystorhinostomy (DCR), will not be effective in alleviating the symptoms. In this situation, tears will not progress to the lacrimal sac and complete bypass of the lacrimal outflow tract with a modified Jones tube must be considered.

Following Bell’s palsy and other types of facial weakness and paralysis, lacrimal pump failure often occurs. This situation is common after removal of acoustic neuromas and squamous cell carcinomas. A normal probing and irrigation of the lacrimal system may be completed, and the flow of fluid into the nasopharynx may be normal. However, a dye retention test may be abnormal and a large amount of dye will remain in the enlarged tear film. In these conditions, the surgeon will often detect significant ectropion, lagophthalmos, and corneal staining in the preoperative evaluation. It is important to exclude these causes of tearing before proceeding with surgery.

In normal eyelids, the lower lid and punctum move medially with each blink. This can be seen easily during slit lamp examination if the upper eyelid is held open and the patient is asked to blink. The absence of movement of the lower eyelid can be an indication of an old facial paralysis that has not completely resolved.

A final indication for endoscopic CDCR is idiopathic hypersecretion. This diagnosis of exclusion is suggested when the outflow tract is normal and there are no identifiable factors causing increased lacrimal gland secretion. The Shirmer 1 will be much higher than normal. Referral to an external disease consultant should be considered prior to arranging surgery. In these cases, the modified Jones tube provides an additional and larger outflow tract to accommodate the increased tear production.

Endoscopic CDCR has several advantages over traditional external CDCR. Among the advantages are the absence of a scar, absence of edema, and ecchymosis, and minimal surgical manipulation of the medial canthus tissue. It also allows improved visualization of the modified Jones tube and adjacent nasal structures once the tube has been inserted into the nose. With minimal external tissue manipulation, ecchymosis and edema of the skin and canthus are rarely present.

Because no medial canthal skin incision is necessary with the endoscopic technique, no dissection of deep subcutaneous tissue is performed. This lack of tissue manipulation contributes to a more rapid healing process, and improves the chance that a properly placed modified Jones tube will remain in position. With the traditional external technique, there is greater chance of tube migration in the healing phase. This change can lead to malposition of the proximal end of the tube or alteration of the angle of the tube. The tube should maintain an approximate 45° downward angle at all times. If this angle is modified, tear drainage can diminish.

Endoscopic intranasal inspection of the distal end of the modified Jones tube is performed immediately after it is placed. This process allows accurate assessment and identification of potential problems. If the tube is too short and does not protrude far enough from the lateral nasal wall, it is at risk for being covered during the healing phase by nasal mucosa. Also, a tube that is too long may touch the nasal septum, causing pain and leading to external extrusion with poor drainage. These problems are easily correctable at the time of surgery by reinserting a different size tube. Therefore it is imperative that the surgeon recognize the problem intraoperatively, when it can easily be corrected.

The relationship of the distal end of the tube to the middle turbinate is also evaluated endoscopically. The middle turbinate must often be infractured early during the surgical procedure to provide appropriate access to the uncinate process. Postoperatively, the turbinate will often migrate to its preoperative position, and may touch or block the distal end of the modified Jones tube. If the surgeon believes that turbinate movement will result in blockage of the tube, a partial turbinectomy should be performed at the time of surgery.

Twenty to thirty minutes prior to the beginning of surgery, the patient is asked to blow the nose, and is then given two sprays of 0.05 % oxymetazoline in the ipsilateral nasal cavity of the planned procedure. This process is repeated 5 min later. Endoscopic CDCR may be performed under monitored intravenous sedation with local anesthesia or general anesthesia, depending on the preferences of the patient and surgeon. After induction of anesthesia, the nasal cavity is packed with approximately 18 in. of 0.5-in. plain gauze soaked in 4 % cocaine solution. If cocaine solution is not available, the surgeon may substitute a mixture of oxymetazoline and 2 % lidocaine with epinephrine. The packing is removed after 5 min.

Under direct visualization, with a 0° rigid endoscope, local injection of 2 % lidocaine with 1:100,000 epinephrine mixed with an equal amount of bupivacaine 0.075 % with 1:200,000 epinephrine is administered to the submucosa of the anterior middle turbinate, uncinate process, and the area anterior and superior to the uncinate. Approximately 3 cc infiltrate is applied with 1.5 in. 25-gauge needle. The nasal cavity is repacked, carefully filling the space between the middle turbinate, and lateral nasal wall with the anesthesia-soaked gauze for another 5 min. This regimen of packing is important to obtain appropriate hemostasis. The face is prepped and draped in an appropriate manner. A sterile field is not necessary.

With endoscopic visualization, the middle turbinate and its position to the lateral nasal wall are inspected (Fig. 15.2). If the turbinate obstructs the view of the uncinate process, or if the surgeon believes that the turbinate will obstruct the osteotomy site in the postoperative phase, then the turbinate can be gently infractured with a blunt periosteal elevator. This same instrument may be used to make an incision at the border of the bone of the lateral nasal wall, and the uncinate process. The uncinate is identified as the first protrusion of the lateral nasal wall that is encountered under the middle turbinate.