Summary for the Clinician

■ There are many causes for canalicular dysfunction, and symptoms can vary according to the

4severity and duration of the underlying disease.

■Local infective causes can include herpes simplex and bacterial canaliculitis.

■Systemic inflammatory causes include LP, ocular cicatricial pemphigoid, SJS.

■Topical medications can be a cause of canalicular obstruction.

■Radiation can have a secondary effect that causes an obstruction.

■Systemic medications such as Taxotere can also lead to canalicular scarring. Proper dosing can reduce the incidence of this.

■Topical ophthalmic treatments can cause canalicular scarring.

■Medications with preservatives can induce chronic inflammation.

■MMC therapy used for the treatment of ocular surface malignancy can produce canalicular disease in approximately 21% of patients.

■Lacrimal stents and plugs may sometimes incite a mucosal inflammatory response, which may lead to secondary fibrosis and the risk of canalicular stenosis.

4.6The Surgical Approach to Managing Canalicular Disease

A micropunctoplasty, such as the three-snip procedure, is useful if punctal stenosis is present with a patent canaliculus and nasolacrimal duct or extreme punctal stenosis prevents canalicular assessment. The purpose is to remove the posterior wall of both the punctal ampulla and 1–2 mm proximal canaliculus, although recent evidence suggests that removal of the posterior ampullary wall alone, without disruption of the canaliculus, may be preferable [7].

In performing a standard punctoplasty, a punctum seeker may be required first to identify and enter the lacrimal punctum, which may then be further dilated with the wider-tipped Nettleship dilator. Three incisions are then made with either a pair of fine Westcott or Vannas scissors; a vertical incision is made through the most posterolateral part of the punctum and ampulla, a second along the avascular superior margin of the canaliculus, and the third removes the flap of tissue thus created.

For complete punctal occlusion, the tip of a 19-gauge needle is inserted bevel up and obliquely—under microscopic illumination—into the punctal “hill” at an angle almost in line with the (presumed) canalicular lumen. The cutting edge of the needle is advanced medially while slowly rotating to bevel down to open the proximal canaliculus. Failure to identify the mucosal-lined lumen signifies a more extensive block, and the patient should be offered open lacrimal drainage surgery with retrograde intubation (discussed in the next section).

If there is complete closure of the canaliculi, external DCR with retrograde intubation should be offered. Although resistance to outflow may appear to be limited to a small segment of a canaliculus (or canaliculi), DCR is advocated for three reasons: First, the full extent of canalicular disease is impossible to determine by probing and may be limited to only a short proximal segment. Second, bypassing the physiological resistance of the nasolacrimal duct with DCR reduces the overall resistance to tear flow, and this will aid drainage, even if canalicular dynamics remain impaired. Third, it is known that some patients will require a secondary bypass tube—even if the reconstructed anastomosis is anatomically patent—and this is best achieved after prior open DCR and carunculectomy.

4.6.1Surgical Technique for Dacryocystorhinostomy with Retrograde Canaliculostomy

If canalicular occlusion occurs within the proximal 7 mm, DCR with retrograde canaliculostomy is the procedure of choice; this marsupializes the healthy distal canaliculus into the conjunctival sac. The extent of canalicular block is established only at surgery, and since a healthy common canaliculus is required to perform retrograde canaliculostomy, the patient should be warned of the possible need for a primary glass bypass tube in the event that no common canaliculus is found. In all cases, carunculectomy should be performed as later placement of a bypass tube is more successful within a previously healed carunculectomy bed.

A large osteotomy should be created as this allows versatility in the positioning of any subsequent Jones canalicular bypass tube. After suturing of the posterior mucosal flaps, the internal common canalicular opening is entered retrogradely using a “1”-gauge Bowman probe that has been bent perpendicularly at about 8–9mm from its end. The probe is passed as far laterally as possible along each canaliculus, and a 1- to 2-mm fenestration is created in the canalicular wall overlying the tip of the probe (Fig. 4.5a); the “pseudopuncta” are intubated, and the DCR is completed in a standard

fashion. If only the common canaliculus is present, its lateral end should be opened into the carunculectomy bed; in this case, and others where only a single canaliculus is retrievable, the returning end is passed through the heavily scarred annulus of the opposite punctum and forced medially through the lid tissues.2 This last manœuvre is assisted by passing a large-bore needle through the tissue first to create a track that enters the upper part of the opened sac, remote from the common canalicular opening.

The patient should be reviewed at about 1 week for removal of sutures and again at 3–4 weeks after surgery for removal of the silicone intubation; by this time, the pseudopunctum will typically have completely healed. “Cheese wiring” of the pseudopuncta will occur within a month if neither end of the stent is returning to the nose through a healthy collagen annulus, and such intubation should be removed at about 3 weeks after surgery.

4.6.2Placement of a Jones Canalicular Bypass Tube3

Primary or secondary placement of a Jones canalicular bypass tube is required if no functioning canalicular tissue is present, with the tube designed to act as a sump drain, permitting gravitational tear flow from the medial tear lake into the nose, aided by the slight subatmospheric pressure in the nose that occurs during inhalation.

Primary placement of a tube during DCR is undertaken after posterior mucosal suturing; the tube requires a 30° downward tilt for optimum drainage, with the distal

2 Monocanalicular stenting is unlikely to stay in place because of the absence of a normal annulus at the pseudopunctum.

3 T his is sometimes referred to as a canaliculo-dacrocystorhi- nostomy or CDCR.

end lying free within the nasal space, somewhat in front of the middle turbinate, and the proximal end positioned hard behind the lower lid margin and immediately posterior to the medial canthal tendon. The mouth of the tube should lie neither too deeply (where it may abut the epibulbar surface) nor too anteriorly (where it will lie proud of the tear lake). After primary placement, the tube should be held somewhat laterally—by passing a 6–0 nylon suture three times around the neck of the tube— with each end of the suture passed through the skin beneath the lower canaliculus and tied over a bolster (fig 4.1c); the tube end is thereby lifted clear of the caruncular bed while conjunctival healing occurs in this area.

Secondary placement of a Jones bypass tube is best accomplished by using a Nettleship dilator to pierce the epithelium at the exact desired position and a track forced through to the nose using the smallest end of the doubleended (“bullhorn”) dilators supplied with commercial tube sets (Fig. 4.5b). An appropriate tube (commonly 11 mm, with a 3.5-mm flange) is placed onto a “1”-gauge lacrimal probe that is passed along the dilated track, and the tube is forced along the track using the end of the thumbnails (Fig. 4.5c); the use of any form of instrument on the tube flange tends to shatter it. The positions of the ocular and nasal ends of the tube should be checked after withdrawing the “1” probe and spontaneous flow of saline verified. Since the patient will previously have had a carunculectomy, the bed of which will have healed, a suture need not be placed around the neck of the tube.

Nasal examination, preferably with endoscopy, although a headlight and speculum are often adequate, aids secondary placement of bypass tubes. Placement is best performed under a short general anesthetic as the vasoconstriction of nasal local anesthesia creates an atypically capacious nasal space and leads to the misguided nasal positioning of the bypass tube.