success rate of 89% [98]. Mean follow-up in this study of 183 patients was 11 months. A second surgery increased the overall success rate to 96%.

3.6.4.3 Complications

The technical failure rate and re-obstruction rate are higher in patients with post-traumatic or post-surgical obstructions than in those with idiopathic obstructions. Nevertheless, no major complications have been reported, and patient compliance and contentment is very high.

3.7 Stent Placement

In 1994 Song et al. Þrst described ßuoroscopic guided insertion of plastic stents into the nasolacrimal duct as an alternative to surgical procedures [73]. Initially, socalled mushroom-stents were used in the treatment of complete obstruction of the lacrimal drainage system. The primary result with these techniques seemed promising [63, 71, 92]. Nevertheless, lacrimal stents can be occluded and in contrast to the excellent technical success rates the long time patency rate decreases to 19.2% after follow-up of 5 years [74]. The main problem of the procedure is the tendency toward obstruction of the stent by granulation tissue or mucoid material in the proximal portion of the mushroom stent [69]. To overcome the limitations of the conventional polyurethane stent designed by Song, a new stent type was designed with alterations made in material and stent-design (TearLeader Stent with HYDROFEEL¨ coating, InterV/PBN Medicals, Denmark). This stent is 6F in diameter and 35 mm in length. It has a slightly S-shaped conÞguration and a tapered ending without the ballooned portion [90]. Additionally, the surface of the stent is hydroffeel coated.

The TearLeader stent set consists of a dilator, a stent pusher, a 0.47 mm angled atraumatic nitinol guide wire with a 7-cm hydrophilic radiopaque ßexible tip and a dacryocystography catheter. For diagnostic purposes and to plan the intervention, dacryocystography is performed in p.a. and lateral views. Digital subtraction dacryocystography is performed before stent implantation to demonstrate the side of obstruction and to exclude anatomical irregularities and variants.

3.7.1 Indications for Stent Placement

It is indicated in patients who suffer from epiphora caused by a complete obstruction of the nasolacrimal drainage system and who refuse surgical procedures or cannot be given general anaesthesia. Stent implantation is done in a retrograde fashion, using special nasolacrimal duct polyurethane stents.

3.7.2 Anaesthesia for Stent Placement

Stent placement can be performed on an outpatient basis under local anaesthesia.

3.7.3Surgical Technique for Stent Placement

The technique for implanting the conventional mushroom stent is described in detail by Song et al. several times has been [72]: a 0.018-in. ball-tipped guide wire is introduced into the nasolacrimal duct system and gently advanced until reaching the inferior meatus of the nasal cavity. It is pulled out of the external naris with a hook. Then a 6,3-F nasolacrimal sheath with a tapered dilator is passed retrogradely over the guide wire into the upper part of the nasolacrimal system. The dilator is removed and the stent is introduced into the sheath until reaching its tip with the help of a pusher catheter. After this, the sheath has to be withdrawn while holding the pusher catheter in place, thus freeing the stent and allowing the mushroom tip to expand within the dilated lacrimal sac. Finally the guide wire is pulled out superiorly and the pusher catheter inferiorly.

In contrast, the method for implanting the TearLeader stent has been simpliÞed to improve the procedure and to advance patient comfort [88]: the most important difference is that no additional sheath for introducing the stent is necessary, thanks to its well-tapered stent ending. The Þrst step of the procedure is to probe the nasolacrimal duct system with a dacryocystography catheter. Then a ßexible angled nitinol guide wire is introduced via the catheter into the nasolacrimal duct system. Under ßuoroscopic guidance the guide wire is

gently pushed forward into the inferior meatus of the nasal cavity until protruding from the external naris.

Before stent implantation, the specially designed tapered dacryocystography catheter from the stent set has to be advanced anterogradely over the guide wire until it leaves the nostril. From the distal end the stent is threaded on the guide wire, immediately followed by a stent pusher. In the next step the stent and the stent pusher have to be retrogradely advanced over the guide wire until they come into contact with the dacryocystography catheter. By carefully Þxing the anastomosis of the dacryocystography catheter (proximal), the stent and the stent pusher (distal) to the guide wire, the stent is brought into position under ßuoroscopic control. After reaching the correct stent position, the guide wire is pulled back while Þrmly holding in place the stent pusher to avoid dislocation of the stent. Then, the dacryocystography catheter and the stent pusher are retracted leaving the stent in its target position.

Dacryocystography followed by forced irrigation is performed immediately after the procedure to assess correct stent position and stent patency.

3.7.4Post-Operative Care and Complications After Stent Placement

Post-interventionally, patients are treated with decongestant eyedrops for at least 1 week. Additionally, antibiotic eye drops are used routinely. Prophylactic oral antibiotics prior to stent implantation are not recommended [88].

Clinical follow-up examinations should be performed at intervals of 1 week, and at monthly intervals thereafter. Reasons for stent occlusion are usually granulation of tissue as well as mucoid impactions in the stent. Two months after implantation, the stent should be removed by grasping it transnasally with a hook or forceps. Rarely, it has to removed endoscopically when it cannot be grasped, or when tight granulation tissue holds it in place (Fig. 3.8).

During stent implantation mild pain sensation might occur, as also blood-tinged nasal discharge after the procedure. Commonly, patients report a foreign body sensation at the medial cantal region for a few days

which spontaneously disappears. Apart from one patient with acute blindness due to an infection after stent implantation [43] no major complications have been reported in the literature and patientsÕ compliance and contentment is very high.

3.7.5 Results of Stent Placement

Many authors agree on the attractiveness of a polyurethane stent used as an alternative to conventional DCR because it offers an easy, effective, safe and reversible way to manage lacrimal drainage problems [33, 42, 65, 69, 90]. However, this method has not yet gained widespread acceptance among ophthalmologists and interventional radiologists. This is due to the long-term results which to date are less than favourable. Even Song et al. decided not to recommend nasolacrimal duct stents as a Þrst-line therapeutic option [37] although having achieved excellent initial clinical results. Yazici et al. came to the same conclusion stating that the success rate of nasolacrimal stent implantation decreases as follow-up lenghtens. Lanciego et al. gathered more optimistic results with a mushroom stent designed by Song in a multicentric study recruiting more than 400 patients, showing a primary patency rate of 59% after 5 years [43]. It is highly interesting, however, that despite these rather discouraging results regarding long-term stent patency, many authors express a point of view indicating that they are not prepared to abandon the possibility of polyurethane stenting in tear duct obstructions straight away. The group of Schaudig and Maas [69], for example, admit that the overall success rate is lower than that reported after conventional DCR, yet they draw the conclusion that reÞnement of the surface and stent design may improve results in the future.

The short-term observation after implantation of the newly designed hydrophilicly coated TearLeader stent has already shown a clear tendency toward more favourable results. This also includes good feasibility and greater patient comfort during the implantation procedure as it is shown in our studies [94] and in the Þrst long-term clinical results reported by FerrerPuchol et al. 2005 (personal communication). However, longer follow-up periods will be required to deÞne the role of stent implantation Þnally.