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Canaliculo-dacryocystorhinostomy (CDCR)

Canaliculo-dacryocystorhinostomy is indicated where there is bicanalicular block with canalicular obstruction situated a minimum of 8mm from at least one of the puncta and for lateral common canalicular block, in which several millimetres of common canaliculus have been obliterated by scar tissue. The principle of the procedure is to excise the block of scar tissue and unite the medial end of one or both canaliculi to the nose, using the lacrimal sac mucosa as a bridging flap; the operation, although technically feasible, carries a much lower success rate than the standard external DCR or surgery for a more medial common canalicular obstruction (Chapter 15) and closed placement of a Lester Jones canalicular bypass tube may be required later if the operation fails.

A standard DCR incision is made but, before mobilising the lacrimal sac and periosteum, probes are placed in the blocked canaliculi, and the overlying medial canthal tendon divided and dissected laterally using blunt or sharp dissection (Figure 17.1a). This dissection is continued laterally until the tips of the canalicular probes are revealed in the underlying tissues, the ends of the canaliculi are transected at their most medial point and fine silicone tubing inserted and pulled laterally, to aid in retraction. If only one canaliculus is patent, either a monocanalicular stent can be used, or the other end of a bicanalicular intubation can be returned to the nasal space through a "blind" passage (via the punctal annulus, if present), ensuring entry into the nasal space well away from the one remaining functional canaliculus.

A large rhinostomy is created and nasal mucosal flaps fashioned (Figure 17.1b); with canaliculo-DCR, however, a very large anterior nasal flap is required and relatively small posterior flap. The lacrimal sac is opened, not in the mid-part of its medial wall - as with ordinary DCR (Chapter 15) -but much more anteriorly at the junction of the medial wall and anterior border; this allows the lacrimal sac to be "unfurled" posteriorly to create a large bridging flap between the back wall of the canaliculi and the small posterior nasal flap. The canalicular mucosa is united to the small anterior edge of

Figure 17.1 Representation of canaliculo-dacryocystorhinostomy:

(a) The lacrimal sac in its fossa with an obstruction of the distal canaliculus and the area of bone removal for the rhinostomy (hatched).

(b) The sites of incision marked: "a" denotes an incision across the most medial portion of the patent canaliculus, "b" the incision in the anterior aspect of the lacrimal sac and "c" the incision in the nasal mucosa to make a large anterior mucosal flap and a small posterior flap.

(c) The anastomosis performed with the anterior nasal mucosal flap sutured to the canaliculus and the lacrimal sac opened out and sutured as a "bridging flap" between the nasal mucosa and the posterior edge of the lacrimal canaliculi.

the lacrimal sac mucosa with two or three 8/0 absorbable sutures and the posterior edge of the sac sutured to the nasal mucosa using 6/0 absorbable sutures.The canalicular intubation is knotted as with a standard DCR, passed into the nasal space and the anterior mucosal anastomosis between the large nasal flap and the anterior edge of the canalicular remnants completed with multiple 8/0 absorbable sutures (Figure 17.1c); it is important to avoid snagging the intubation with the cutting edge of the needles whilst performing the anterior mucosal union. Finally the DCR wound is closed in a standard fashion and the intubation left in place for several months. If watering continues at 9-12 months after canaliculo-DCR, closed placement of a Lester Jones canalicular bypass tube is required.

Complications

Although canaliculo-DCR has the same spectrum of complications as simple DCR (Chapter 15), the commonest specific complication is failure of tear drainage due to reobstruction of the fine surgical anastomosis. Trephination and silicone intubation may be tried where the obstruction is a small membrane, but in most cases the closed placement of a Lester Jones bypass tube will required.

Dacryocystorhinostomy with retrograde canaliculostomy

Indications

This procedure is designed to open onto the lid margin, in the region of the medial tear lake, canaliculi that are blocked within their first 6-7mm but are patent in the distal part; it being, of course, only possible to establish this at the time of surgery and so the patient must be warned that a glass canalicular bypass tube might be required if there is insufficient canaliculus to allow a retrograde canaliculostomy.

A standard external DCR is performed to the point of opening the lacrimal sac and suturing of the posterior mucosal flaps (Chapter 15). The common canalicular opening is located in the usual fashion and a "0" gauge lacrimal probe, bent perpendicularly on itself at about 8-10mm from the end, is then passed from the sac, into the common canaliculus (Figure 17.2a) and as far laterally as possible along each canaliculus. The probe is pushed up against the lid margin and a cut down made onto the end of the probe, opening the canaliculus onto the lid margin (Figure17.2b) and the same manoeuvre repeated for the other canaliculus, if possible. The "false" puncta are intubated and the DCR completed in a standard fashion; if only one canaliculus is present, the other end of the intubation is returned to the nasal space through a "blind" passage. A monocanalicular stent placed in the pseudo-punctum is unlikely to remain in position in the absence of the normal punctal annulus.

The intubation can be removed when the epithelium of the canaliculus and the conjunctiva have united and there is little need to leave them more than 3-4 weeks, or the tubes will tend to "cheese wire" through the tissues and cause a medial cross-union between the eyelids. If the pseudo-puncta fail to control symptoms, closed placement of a canalicular bypass tube is required.

Dacryocystorhinostomy and Jones canalicular bypass tube

The canalicular bypass tube is designed to establish tear drainage, from the medial tear lake into the nose, by way of a false conduit; the most used device being the Pyrex glass (Lester Jones) canalicular bypass tube. Placement of a bypass tube is indicated where the extent of canalicular obliteration is such as to preclude either canaliculo-DCR or DCR with retrograde canaliculostomy, or where watering continues in the face of a functioning

Figure 17.2 Retrograde canaliculostomy during dacryocystorhinostomy: (a) the angled "0" gauge probe is being directed towards the internal opening of the common canaliculus in the left lacrimal sac; (b) a cut-down on the lid margin is directed onto the most lateral point reached by the probe placed retrogradely into the canaliculus.

Figure 17.2 Retrograde canaliculostomy during dacryocystorhinostomy: (a) the angled "0" gauge probe is being directed towards the internal opening of the common canaliculus in the left lacrimal sac; (b) a cut-down on the lid margin is directed onto the most lateral point reached by the probe placed retrogradely into the canaliculus.

standard DCR - as, for example, in patients with facial nerve palsy.

As with DCR and retrograde canaliculo-stomy, a standard external DCR is performed to the stage of suturing the posterior mucosal flaps although, if no lacrimal sac is present or flaps cannot be formed, the posterior nasal mucosa should be sutured to the soft tissues of the lacrimal sac fossa. Although a large rhinostomy is important for all lacrimal surgery (Chapter 15), it is particularly important when placing a canalicular bypass tube, or the tube tends to become displaced due to its bearing on the bone at the lower edge of the rhinostomy. The nasal cavity should also be examined and, if necessary, the anterior part of the middle turbinate should be de-boned or trimmed to make extra room for the medial end of the tube.

If retrograde exploration of the common canaliculus fails to reveal any useful tissues for retrograde canaliculostomy, a carunculectomy may be performed with care being taken to avoid damage to the plica semilunaris. A sharp guide wire is inserted from the medial canthus into the nose (Figure 17.3).The point of entry is critical to the functional success of the tube and should be at the level of the undisplaced lower eyelid margin, at the site of carunculectomy. An alternative site is the lateral 2-3mm of the canaliculus which, if present, can be laid open to accommodate the lateral flanged end of the bypass tube. The wire marks the future track of the tube and is directed about 15-25° downhill in the coronal plane, the medial end passing into the nose in the vicinity of the lacrimal sac fossa.

A small trephine (1^5-2mm diameter) is passed over the guide wire to remove a narrow core of tissue and, whilst the trephine is in the tissues, the sharp wire may be replaced with a blunt one. A glass canalicular bypass tube is slipped over the guide wire and pushed firmly through the tissues so that the distal end is at least 2mm clear within the nasal space; the end of a thumb-nail should be used to drive the tube into the tissues, as instruments tend to shatter the glass flange of the tube. The neck of the tube is encircled with three turns of a 6/0 nylon suture, passed through the medial end of the lower lid and tied over the bolster - this suture lifting the tube slightly laterally to allow epithelial healing around (and not over) the lateral end of the bypass tube. In most cases a 12mm tube with a 3-5mm flange is suitable for caruncular placement, whereas a somewhat longer (16mm) tube may be needed where the neck of the bypass tube is placed within the lateral canalicular remnant.

The anterior mucosal anastomosis and surface closure is completed as with standard external DCR. The encircling suture is

Lester Jones Tube
Figure 17.3 A system for insertion of a Lester Jones bypass tube using a guide wire, trephine and "dipstick". (Reproduced with permission from Morlet GC. A modern approach to lacrimal surgery. Aust NZ J Ophthalmol 1988; 16:202.)

removed at 7-10 days after surgery, at the time of suture removal from the skin incision.

Canalicular bypass tubes are subject to a number of common complications and require regular monitoring and maintenance, otherwise they become caked or blocked with mucus debris from the tear film and this results in recurrent conjunctivitis. Patients should be encouraged to sniff water from the tear lake, through the tube and into the nose, on a daily basis and they should also be taught to place one of their fingers over the tube when violently sneezing or nose blowing.

Lateral migration of the tube occurs most often and the tube will sometimes be completely dislodged, when closed replacement should be undertaken. Repeated episodes of tube extrusion generally occur due to residual bone in the area of the rhinostomy and, in such cases, open revision of the rhinostomy should be undertaken. More rarely the tube will sink medially into the tissues and may require a cut-down to retrieve it.

Malposition of the ocular end of the tube may result in failure of tear drainage where the tube is too anterior or, more usually, the tube is too posterior and becomes embedded in conjunctiva or against the globe, causing episcleritis. In more extreme cases, the irritation will cause formation of a pyogenic granuloma - this being particularly troublesome where the tube has become filthy through neglect. In such cases of malposition with secondary inflammation, the tube should be removed and replaced in a better position at a later date when the inflammatory changes have settled.

Build-up of tear-film debris on the surface of a bypass tube tends to lead to obstruction and repeated ocular infections. If the obstruction cannot be cleared with the tube in place, the device should be removed and cleaned, or else replaced.

Closed placement of a canalicular bypass tube

Indications

Closed secondary placement of a glass canalicular bypass tube is indicated when a previously inserted bypass tube has become dislodged, after failed canaliculo-DCR or retrograde canaliculostomy, or where, in the absence of reflex lacrimation, a functioning DCR fails to control watering.

The procedure is similar to a primary (open) bypass tube, except that the DCR has already been performed and the rhinostomy does not have to be opened; in other words, the tube is inserted in a closed fashion. For optimum positioning of the distal end of the bypass tube, nasal examination is required and is best achieved with endoscopy, although a good headlight and nasal speculum are often adequate. A 3mm diameter rigid sucker is required to clean the nasal space during surgery. The procedure is best performed under general anaesthesia as vasoconstriction from the endonasal local anaesthesia encourages, due to an artificially shrunken middle turbinate and septal mucosa, a misjudgement of the position of the nasal end of the tube.

First-time placement of a closed Jones' tube is similar to the open canalicular bypass tube, using and positioning the guide wire and trephine in the same way; the intranasal position of the introducer should be checked endoscopically and, if necessary, the anterior part of the middle turbinate removed to make room for the tube. If there has recently been a satisfactorily functioning tube, the double-ended ("bullhorn") dilator that accompanies the commercial sets of tubes may be used to dilate the previous track and the tube forced into place along an "0" gauge probe introduced into the dilated track. After placement of any bypass tube, the position of both the ocular and the nasal ends of the unsupported tube should be checked and it is particularly important to verify that the nasal end lies free within the nasal cavity and not up against the septum, lateral wall or turbinate. A newly-placed tube needs to be secured in the same way as a primary tube, but a replacement tube does not need fixation.

Medial canthoplasty during lacrimal surgery

Where injury to the lacrimal drainage system has been accompanied by significant midfacial trauma, there may be traumatic telecanthus or canthal dystopia and repositioning of the canthus may be required as part of the lacrimal surgical repair. Malpositions of the canthus secondary to trauma are, however, notoriously difficult to correct and, despite the best efforts, the canthus tends to drift back towards its previous position.

Traumatic telecanthus may be due to a widening of the fractured midfacial skeleton and the first step required may be to remove excess bone at the inner canthi, this then presenting difficulty with the medial fixation of the inner canthi in the absence of a firm bony anchor. In this setting a transnasal wire is helpful (Chapter 6) or a small T-plate or anchor-screw - to which to fix the canthal tendon - may be inserted into the remaining fragments of the nasal bones. To facilitate a medial repositioning of the lids, it is important to widely mobilise the medial attachments of the eyelids.

If canthal repositioning is being performed at the time of open lacrimal surgery, advantage can be made of exposure of the posterior lacrimal crest and this fascia used as an anchor point for elevating the medial end of the lower eyelid. Although some results will be encouraging (Figure 17.4), on occasion this site of postero-superior fixation lacks rigidity.

The superficial tissues may need to be redistributed at the time of surgery. In traumatic canthal dystopia, the canthus is generally shifted downwards and a triangular pedicle flap of skin, based medially on the side of the nasion, may be transposed from the upper eyelid to the lower; this thereby helping to raise the inner canthus by correcting any vertical shortage of tissues below the medial canthus (Figure 17.5).

Figure 17.4 Medial canthoplasty performed at the time of open lacrimal surgery: (a) pre- and (b) post surgery. Although there is an improvement in the canthal position and elevation after postero-superior fixation of the lower eyelid, this is limited by scarring at the site of the previous injury.

Figure 17.5 Redistribution of the soft tissues as part of a medial canthoplasty for inferior displacement of the medial canthus. The apex 'A' of the flap of skin and muscle is transposed from the upper eyelid (a) into the lower (b) after fixing the canthal structures deeply to bone or periosteum.

Figure 17.5 Redistribution of the soft tissues as part of a medial canthoplasty for inferior displacement of the medial canthus. The apex 'A' of the flap of skin and muscle is transposed from the upper eyelid (a) into the lower (b) after fixing the canthal structures deeply to bone or periosteum.

Further reading

Bartley GB, Gustafson RO. Complications of malpositioned Jones tubes. Am J Ophthalmol 1990; 109:66-9.

Call NB, Welham RAN. Epiphora after irradiation of medial eyelid tumors. Am J Ophthalmol 1981; 92:842-5.

Chapman KL, Bartley GB, Garrity JA, Gonnering RS. Lacrimal bypass surgery in patients with sarcoidosis. Am J Ophthalmol 1999; 127:443-6.

Coster DJ, Welham RAN. Herpetic canalicular obstruction. Br J Ophthalmol 1979; 63:259-62.

Henderson ON. A modified trephining technique for insertion of Lester Jones tube. Arch Ophthalmol 1985; 103:1582-5.

Hicks C, Pitts J, Rose GE. Lacrimal surgery in patients with congenital cranial or facial anomalies. Eye 1994; 8:583-91.

Jones BR. The surgical cure of obstruction of the common canaliculus. Trans Ophthalmol Soc UK 1960; 80:343-56.

Kwan ASL, Rose GE. Lacrimal drainage surgery inWegener's granulomatosis. Br J Ophthalmol 2000; 84:329-31.

McLean CJ, Rose G.E. Post-herpetic lacrimal obstruction. Ophthalmology 2000; 107:496-9.

McNab AA. Lacrimal canalicular obstruction associated with topical ocular medication. Aust NZ J Ophthalmol 1998; 26:219-24.

McNab AA. Diagnosis and investigation of lacrimal disease. In: McNab AA, ed, Manual of orbital and lacrimal surgery (2nd ed). Oxford: Butterworth Heinemann, 1988: 91-8.

Morlet GC. A modern approach to lacrimal surgery. Aust NZ J Ophthalmol 1988; 16:199-204.

Rose GE, Welham RAN. Jones' lacrimal canalicular bypass tubes: twenty-five years' experience. Eye 1991; 5:13-19.

Sanke RF, Welham RAN. Lacrimal canalicular obstruction and chicken pox. Br J Ophthalmol 1982; 66:71-4.

Steinsapir KD, Glatt HJ, Putterman AM. A 16-year study of conjunctival dacryocystorhinostomy. Am J Ophthalmol 1990; 109:387-93.

Wearne MJ, Beigi B, Davis G, Rose GE. Retrograde intubation dacryocystorhinostomy for proximal and mid-canalicular obstruction. Ophthalmology 1999; 106:2325-8.

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