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BOOK
EXCERPT Chapter
15 INTRODUCTIONTherapeutic occlusion of the lacrimal canalicular system was first performed in 1877 to seal off the lacrimal sac from the ocular surface in patients with infectious dacryocystitis.1 It was not until the 1890s that therapeutic punctal occlusion was used to prevent the drainage of tears in patients with xerophthalmus.2–4 This simple procedure is the most common surgical treatment of dry eye today and is indispensable in the management of tear insufficiency associated with KCS, GVHD, Sjögren’s syndrome, neurotrophic and exposure keratitides, cicatricial conjunctivitis, post–LASIK dry eyes, and SLK.5 The lacrimal puncta can be occluded by thermal methods, by implantation of plugs, or with more complex surgical methods requiring incisions and sutures. Punctal and canalicular closure increases mainly the aqueous component of natural tears, but also has secondary beneficial effects on goblet cell density, tear film stability, and tear osmolality.6–8 The procedure also increases the retention of artificial tears. Objective and subjective signs and symptoms of xerophthalmus are both improved. This, in turn, results in improved visual acuity, reduced punctate staining of the ocular surface, diminished mucous discharge, relief from foreign body sensation, improved tolerance of contact lenses, and reduction in the frequency of artificial tears. The procedure is associated with very few complications. These include epiphora, spontaneous reopening of the punctum, canaliculitis, dacryocystitis,9 and toxic medicamentosus (from increased retention of topical medications).10 Additionally, complications unique to punctal and canalicular plugs include abrasion of the ocular surface by the exposed ends of the implants,8,11 pruritus,10,12 dacryocystitis (from the migration of plugs into the common canaliculus),13 pyogenic granuloma,13 and extrusion. Although upper and lower canaliculi have very similar drainage capabilities, the inferior canaliculi may have slightly more activity.14 Closure of one canaliculus may not necessarily translate to a 50% improvement in objective and subjective measures because the unoccluded side may increase its drainage activity in response. THERMAL OCCLUSION AND LASER PHOTOCOAGULATIONThermal punctal and canalicular occlusion may be performed with a hot cautery, diathermy, or argon laser to cause destruction, shrinkage, and scarring of the punctal opening and the wall of the proximal lumen. Thermal cautery is the oldest technique, dating back to the late 1800s,1 and is simpler, quicker, and less costly than diathermy or laser photocoagulation. It is currently the most common method of thermal punctal occlusion.
The hot cautery method utilizes the direct transmission of heat from a hot probe to produce a controlled burn injury to the punctal opening. It is most frequently performed with a battery-operated unit with an electrically-heated nichrome wire tip (galvanocautery) (Figure 15-1), although wall-current units are also available. In some parts of the world, punctal cauterization is still performed with a hot needle heated with an alcohol lamp. Although low temperature cauterization may provide better control of tissue destruction, some surgeons prefer higher temperatures to produce deeper scarring and shrinkage for longer-lasting results. The procedure is performed in the outpatient clinic under local infiltrative anesthesia with a lidocaine injection into the tissues surrounding the punctum. Cauterization may be performed at the slit lamp, under an operating microscope, or with magnifying loupes. It is important to treat not only the surface of the punctum, but to also insert the tip of the cautery gently into the proximal lumen to achieve a more effective and permanent closure. In many successful occlusions, a clear membrane eventually covers the surface of the punctal opening. In cases of late punctal occlusion failure, the wall of the canalicular lumen becomes re-epithelialized through the normal reparative process of cell migration. Temporary tissue edema postoperatively may sometimes functionally obstruct the punctum and canaliculus, but with resolution of the edema, the channel may reopen.
Diathermy utilizes radiofrequency (455 kHz to 100 mHz) energy to heat the tissues in the area of the punctal opening and proximal lumen. Some diathermy units employ a second electrode on the patient’s torso or limb to complete the electrical circuit. In others, the electrodes are placed in close proximity to each other (eg, bipolar pencil or forceps-style cautery tips), thus negating the need for a remote, second electrode pad. The diathermy procedure is performed under local infiltrative anesthesia. A fine-needle electrode is introduced into the canaliculus through the punctum and the electromagnetic current is activated until the surrounding tissues blanch and contract. Available commercial diathermy units include the Hyfrecator (ConMed Corp, Utica, NY), Mentor Diathermy (Mentor Ophthalmics, Santa Barbara, Calif), and Surgitron (Ellman International, Oceanside, NY). Argon laser photocoagulation for punctal occlusion15,16 may be done under either topical or local anesthesia. After the punctal opening is first encircled with laser spots, additional spots are then delivered into the punctum itself (Figure 15-2). Laser treatment on average has a shorter duration of effect compared to thermal cautery.16,17 If the patient experiences significant epiphora after any of the aforementioned thermal punctal occlusion methods, the obstruction may be reversed in some cases by using a punctal dilator to probe and dilate the punctal opening and the proximal canaliculus.9 If this fails, more invasive methods, such as passage of a pigtail probe, incision of the eyelid margin medial to the punctum with marsupialization of the canaliculus, or (in extremely rare instances) a full dacryocystorhinostomy, may become necessary. PUNCTAL OBSTRUCTIONThe lacrimal punctum and canaliculus may be occluded temporarily or permanently with tissue glue or implanted foreign bodies. Temporary occlusive procedures are useful in assessing the beneficial effects of lacrimal obstruction prior to resorting to permanent occlusion. PUNCTAL OBSTRUCTION WITH GLUECyanoacrylate tissue adhesive may be applied to the punctal opening or into the proximal canaliculus, using a 25- to 27-gauge cannula or needle.7,18 A new fibrin surgical glue (Tisseel VH, Baxter Healthcare, Deerfield, Ill) is now available and may possibly be used as an alternative to cyanoacrylate adhesive. Typically, occlusion with glue lasts only several days to week because the epithelial cells lining the punctal opening and the walls of the proximal lumen slough during the natural cell-turnover cycle. PUNCTAL OBSTRUCTION WITH ABSORBABLE IMPLANTS
Implantation of absorbable plugs may be performed with or without topical anesthesia. Small punctal openings may require dilation before insertion of plugs, but care should be taken to not excessively dilate and damage the fibrous ring surrounding the punctal opening. Plugs are inserted with toothless pincers, such as the jeweler’s forceps (Figure 15-3). The insertion may be facilitated by gentle lateral traction on the eyelid. Absorbable collagen punctal plugs and canalicular implants are available from Alcon Laboratories (Fort Worth, Tex), Ciba Vision (Atlanta, Ga), FCI Ophthalmics (Marshfield Hills, Mass), Lacrimedics (Eastsound, Wash), and Oasis Products (Glendora, Calif). Catgut (2—0) or chromic catgut (4—0) sutures are absorbable materials (collagen matrix) that can be used instead of collagen plugs. Any desired length of suture may be cut and inserted into the canaliculus. This inexpensive material is used by some surgeons to temporarily enhance the tear film in the immediate postoperative phase after corneal surgery. PUNCTAL OBSTRUCTION WITH NONABSORBABLE IMPLANTS AND PLUGSNonabsorbable implant materials include polyethylene, silicone, and acrylic. Silicone and polyethylene implants are made in a variety of shapes and sizes to facilitate insertion, prevent extrusion, and inhibit distal migration. The implant shape may determine whether the punctum is partially or completely occluded. Silicone and polyethylene implants are generally safe and effective. Although they are considered “permanent,” they are usually removable with varying degrees of difficulty.21 Insertion of silicone and polyethylene plugs is performed with or without topical anesthesia and magnification (Figure 15-4). Punctal dilation is typically required before insertion. The implants are typically preloaded on an inserter for direct placement into the punctal orifice. Gentle horizontal eyelid traction helps evert the punctum to facilitate insertion. When the shaft of the implant is located in the vertical portion of the canaliculus and the head (flange) of the implant protrudes above the punctum, the implant is released from the inserter. Some inserters have a built-in button to release the implants, while others require forceps to hold the implant in position while the inserter is withdrawn. This type of punctal plug implant is visible under slit lamp biomicroscopy and can readily be removed with jeweler’s forceps.
A newer, nonabsorbable implant made from hydrophobic acrylic (SmartPlug, Medennium Inc, Irvine, Calif) is now available. This material is heat responsive and its physical dimensions undergo transition from 9.0 x 0.4 mm to 2.0 x 1.0 mm at temperatures above 32°C. No sizing of the punctal opening is required because one plug size fits all puncta before heat activation. Insertion may be done with or without topical anesthesia and magnification. The implant is inserted approximately two-thirds of its length into the canaliculus with special SmartPlug forceps. The implant retracts itself into the canaliculus as the heat-activated conformational change pulls it distally. As the implant molds to the dimensions of the vertical canaliculus, the exposed portion retracts completely into the punctum. The SmartPlug is not visible once it attains its final position. Removing the SmartPlug requires grasping the implant at the punctal orifice with jeweler’s forceps if it is visible or flushing the implant distally into the lacrimal sac with saline solution. Other companies in the United States (Form Fit, Oasis Products, Glendora, Calif) and Japan have now developed similar heat-sensitive plugs. Recurrent extrusion of flanged surface punctal plugs may be an indication for switching to these heat-sensitive implants or to thermal occlusion. PUNCTAL AND CANALICULAR IMPLANT INFECTIONS AND INFLAMMATIONSerious but rare complications of both punctal plugs and canalicular implants include canaliculitis (infectious or noninfectious) and implant migration.22 Initial treatment of the former requires systemic antibiotics, irrigation of the canaliculus, and drainage of suppurative material; however, recurrences after the initial episode are very common. Surgical removal of the implant via an incision through the palpebral conjunctiva into the canaliculus or a full dacryocystorhinostomy may be necessary in recalcitrant cases. Distal implant migration may occur spontaneously or following forceful insertion. Diagnosis may be aided by checking for canalicular patency with punctal irrigation and by ultrasound biomicroscopy.23 Initial management of implant intrusion involves observation, but if the implant causes complications, canalicular surgery or dacryocystorhinostomy would be warranted to remove the problematic implant.22 Punctal surface implants with inserter holes may collect debris that may become colonized with microorganisms. Rarely, tear stasis from the punctal obstruction may predispose the patient to ocular infection.24 PUNCTAL OCCLUSION TECHNIQUES REQUIRING SUTURE AND INCISIONSIf punctal occlusion fails multiple times, it may become necessary to resort to more extensive surgical procedures that involve suturing and incision. These procedures are more time consuming and may commensurately be associated with greater surgical morbidity and complications. The punctum may be occluded first with a hot cautery and then sutured shut with a single nylon stitch. Alternatively, the vertical canaliculus may be sutured shut with a single 8—0 polyglactin full-thickness eyelid mattress suture tied on the skin side. If desired, these techniques can also be combined with nonthermal punctal epithelial debridement. A more extensive procedure employs surgical laceration of the horizontal canaliculus medial to the punctum on the eyelid margin, thermal cauterization of the exposed canalicular and punctal surfaces, and suture closure of both the canaliculus and punctum (Figure 15-5).25 Complete canalicular excision is a rarely performed procedure in which the canaliculus is identified with a probe and extirpated through either a lid margin or palpebral conjunctival incision.26 The operation is associated with a risk of eyelid distortion and is best performed by a surgeon experienced in canalicular and cosmetic eyelid procedures.
A medial tarsorrhaphy procedure can be modified to incorporate simultaneous occlusion of the upper and lower puncta.27 In this technique, a rectangle of epithelial tissue is removed from around both the upper and lower puncta. The denuded surfaces of the medial eyelid margins are approximated with 8—0 polyglactin sutures, resulting in occlusion of both puncta. A standard medial temporary tarsorrhaphy is then performed with a mattress suture over protective bolsters. This procedure is ideal for patients with severe tear deficiency and in cases of severe neurotrophic or exposure keratitis. There are several less complicated surgical techniques that are also more readily reversible.27 A bulbar conjunctival autograft taken from one of the fornices can be sutured as a patch over the punctal orifice after a similar sheet of epithelial tissue surrounding the punctum is excised. The patch graft is secured with 4 polyglactin (8—0) or nylon (10—0) sutures (the latter are removed after 1 week). The procedure may be reversed by simply removing the tissue patch. Another technique is the translocation of the punctal orifice away from the tear lake. The vertical canaliculus is identified with a probe and moved anteriorly through the anterior lamellae of the eyelid, in effect moving the punctal orifice to the eyelash line. Reversal involves translocation of the punctum back to its original position. CONCLUSIONPunctal occlusion is a very effective invasive method of treating dry eye and other ocular surface disorders. Methods of occlusion include tamponade by implants, as well as thermal and surgical occlusion. In general, the latter methods should be reserved for severe cases of tear deficiency.
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