Deutsche Forschungsgemeinschaft (German Research Association; FOR 2240 "(Lymph)Angiogenesis And Cellular Immunity In Inflammatory Diseases Of The Eye" to LMH; HE 6743/2-1 and HE 6743/3-1 to LMH), GEROK program of the University of Cologne to KRK and LMH. Our gratitude goes to Dr. K&#252;hner for technical support.

For this procedure, informed consent is required and has been obtained for every patient who has undergone surgery in the Department of Ophthalmology, University of Cologne, Cologne, Germany. All examinations and surgical interventions were executed in accordance with national laws and the declaration of Helsinki from 1975 in its current version.
NOTE: Unless indicated otherwise, instructions will always only refer to the side on which the procedure is being performed. Use sterilized equipment.
1. Patient Preparation
<ol>
	<li>Perform a thorough ophthalmic examination (with special attention to eyelids, upper and lower punctum, and tear drainage) including irrigation and probing to test for PANDO10.
	<ol>
		<li>For standardized irrigation, insert a Bangerter probe into the upper and, subsequently, lower punctum. Begin by inserting it vertically, then tilt it toward the temple into a horizontal position to follow the physiological formation of the canaliculus. When the probe is in position, carefully inject saline to test for lacrimal duct obstruction. 
		NOTE: In infrasaccal PANDO, the Bangerter cannula will easily reach the lateral nasal wall without a bouncy resistance (&#34;hard stop&#34;). Trying to irrigate will result in contralateral reflux through the opposite punctum without any fluid reaching the patient&#39;s pharynx10.</li>
	</ol>
	</li>
	<li>Rule out acute infections, tumors of the tear drainage system as well as traumatic, congenital or presaccal obstruction.
	<ol>
		<li>To rule out acute infections, look for painful reddening, swelling or purulent discharge of the tear drainage. To rule out tumors, look for indolent swelling, ulceration or pigmentation. Presaccal obstruction results in a bouncy resistance when trying to advance the Bangerter Probe into the lacrimal sac (&#34;soft stop&#34;). Congenital and traumatic obstruction can be ruled out by taking patient history10,19,20.</li>
	</ol>
	</li>
	<li>Rule out intranasal rhinological pathologies, e.g. severe septum deviation. This should be done by taking the patient&#39;s history in combination with a rhinological inspection of the nasal cavity 21.</li>
	<li>Put the patient under general anesthesia, e.g. by intravenous injection of propofol, remifentanil, and atracurium for induction and inhalation of desfluran plus intravenous remifentanil for maintenance, using standard weight-adapted dosing10. Intubation should be performed, but use of a larynx mask is also possible. 
	NOTE: Anesthetics as well as dosages may vary between clinics. No specific anaesthesia protocol is required for laser-assisted DCR.</li>
</ol>
2. Laser-assisted DCR
<ol>
	<li>Insert the video-assisted endoscope into the nasal cavity by carefully advancing it through the nostril. Visualize the anterior margin of the middle turbinate by slightly tilting the endoscope towards the lateral nasal wall.</li>
	<li>Set up the laser equipment and laser settings to the correct values. Put on protective glasses.
	<ol>
		<li>Connect the laser fiber optic (diameter 400 &#181;m) to the diode laser (wavelength 810 nm). Set the diode laser settings to 6 - 8 W, 200 ms pulse duration, 100 ms exposition pause.</li>
		<li>Fit the laser fiber optic into the hand-piece for maneuvering and through a blunt cannula. Let 2 - 3 mm of the fiber stick out at the tip of the cannula.</li>
		<li>Perform carbonization of the laser fiber tip by holding it on a wooden spatula and applying laser energy for a few seconds until the tip is sufficiently blackened. 
		NOTE: This will limit unwanted energy distribution to the tissue of the lacrimal sac.</li>
	</ol>
	</li>
	<li>Position the laser fiber correctly at the lateral nasal wall.
	<ol>
		<li>Use a lacrimal probe to dilate the&#160;lower punctum (Figure 2a). Insert the probe in a vertical orientation at first and then bring into a horizontal orientation before further advancing it towards the lacrimal sac. This will allow for the laser fiber to be inserted smoothly in the next step.</li>
		<li>Insert the laser fiber into the lower canaliculus (Figure 2b, 2c). Begin by inserting it vertically, then tilt it toward the temple into a horizontal position to follow the physiological formation of the lower canaliculus.</li>
		<li>Carefully advance the laser fiber into the lacrimal sac until it touches the lateral nasal wall, i.e. the medial lacrimal saccal wall. There, aim the tip in an antero-inferior direction so that it points to the anterior margin of the middle turbinate.</li>
		<li>Verify correct positioning endoscopically by monitoring transluminescence of the aiming beam at the height of the anterior margin of the middle turbinate (Figure 2d).</li>
	</ol>
	</li>
	<li>Create a sufficient nasolacrimal bypass by application of pulsed laser energy to the nasal wall.
	<ol>
		<li>Apply laser energy (using the parameters set above), keeping constant contact to the wall without pressure, aiming for the anterior margin of the middle turbinate. The laser will vaporize the tissue directly in front of it, creating a nasolacrimal bypass (Figure 2d, 2e). 
		NOTE: The total energy required ranges between 0.9 - 1.8 kJ and tends to vary between patients.</li>
		<li>Ensure that the fiber tip is not actively pressed against the wall. Be careful not to let the tip slip back into the metal cannula as this will cause thermal injury due to heating of the metal. Also avoid sideways movements as the tip can break off.</li>
		<li>Upon penetrating the lateral nasal wall, pull the laser fiber back a bit and enlarge the ostium by carefully vaporizing the margins in a circular manner. Try to create as large a bypass as possible (Figure 2f).</li>
		<li>Aim for a total diameter of 5 mm for the ostium.</li>
		<li>Stop applying energy and remove the laser fiber together with the hand-piece and the cannula by carefully retracting the equipment.</li>
	</ol>
	</li>
	<li>Verify the patency of the ostium by saline irrigation using a Bangerter probe as described in 1.1.1. If a patent ostium was created, successful irrigation should be visible endoscopically.</li>
	<li>Remove the Bangerter probe.</li>
	<li>Place the silicon tube (Figure 2g).
	<ol>
		<li>Through the lower punctum, insert a monocanalicular silicon tube and carefully advance it until the leading metal tip passes the bony ostium and protrudes into the nasal cavity.</li>
		<li>Use Blakesley forceps to grab the tip from inside the nasal cavity and pull the silicon tube out of the nose and into position (Figure 2h).</li>
		<li>Use a pair of scissors to shorten the silicon tube. The end should not be sticking out of the nose.</li>
		<li>Perform silicon intubation via the upper canaliculus as well (following steps 2.7.1 through 2.7.3) (Figure 2h).</li>
	</ol>
	</li>
	<li>Remove the nasal endoscope.</li>
</ol>
3. Post-op Care and Follow-up
<ol>
	<li>After surgery, initiate treatment with antibiotic eye drops (e.g. ofloxacin), decongestant eye drops (e.g. xylometazolin) and steroidal eye drops (e.g. prednisolone acetate). Antibiotics can be stopped after one week, while steroidal and decongestant eye drops should slowly be weaned off over the course of one month.</li>
	<li>Follow-up at six weeks and three months after surgery. Look for resolution of symptoms, silicon tube prolapse, infection, and secretion.</li>
	<li>Remove silicon tubes at three months after surgery by simply grabbing the T-shaped end at the height of the puncta and carefully pulling them out.</li>
</ol>

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A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dacryocystorhinostomy+for+Acquired+Nasolacrimal+Duct+Stenosis+in+the+Elderly+(&#8805;80+Years+of+Age).">Dacryocystorhinostomy for Acquired Nasolacrimal Duct Stenosis in the Elderly (&#8805;80 Years of Age).</a> Ophthalmology. , (2016).</li><li>Detorakis, E. T., Drakonaki, E., Papadaki, E., Pallikaris, I. G., Tsilimbaris, M. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Watery+eye+following+patent+external+DCR:+an+MR+dacryocystography+study.">Watery eye following patent external DCR: an MR dacryocystography study.</a> Orbit. 29 (5), 239-243 (2010).</li><li>Kakizaki, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+lacrimal+canaliculus+and+sac+bordered+by+the+Horner's+muscle+form+the+functional+lacrimal+drainage+system.">The lacrimal canaliculus and sac bordered by the Horner's muscle form the functional lacrimal drainage system.</a> Ophthalmology. 112 (4), 710-716 (2005).</li><li>Emmerich, K. H., Ungerechts, R., Meyer-R&#252;senberg, H. 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A., Kal, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endocanalicular+diode+laser+dacryocystorhinostomy+for+nasolacrimal+duct+obstruction:+short-term+results+of+a+new+minimally+invasive+surgical+technique.">Endocanalicular diode laser dacryocystorhinostomy for nasolacrimal duct obstruction: short-term results of a new minimally invasive surgical technique.</a> J. Craniofac. Surg. 21 (6), 1932-1934 (2010).</li><li>Drnovsek-Olup, B., Beltram, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcanalicular+diode+laser-assisted+dacryocystorhinostomy.">Transcanalicular diode laser-assisted dacryocystorhinostomy.</a> Indian. J. 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Otorhinolaryngol. 270 (8), 2255-2261 (2013).</li><li>Plaza, G., Beter&#233;, F., Nogueira, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcanalicular+dacryocystorhinostomy+with+diode+laser:+long-term+results.">Transcanalicular dacryocystorhinostomy with diode laser: long-term results.</a> Ophthal Plast Reconstr Surg. 23 (3), 179-182 (2007).</li><li>Heindl, L. M., Junemann, A., Holbach, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+clinicopathologic+study+of+nasal+mucosa+in+350+patients+with+external+dacryocystorhinostomy.">A clinicopathologic study of nasal mucosa in 350 patients with external dacryocystorhinostomy.</a> Orbit. 28 (1), 7-11 (2009).</li><li>Heindl, L. M., Treutlein, E., J&#252;nemann, A. G., Kruse, F. E., Holbach, L. 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No conflict of interest.

Transcanalicular laser-assisted DCR as described above is a fairly quick, minimally invasive way to treat absolute infrasaccal nasolacrimal duct obstruction effectively without the need for skin incision, thus sparing not only the skin but also the medial canthal tendon and the physiological canalicular pump mechanism. While the procedure is well suited for patients with primary acquired nasolacrimal duct obstruction, pathologies other than idiopathic stenosis do not qualify for this procedure. This is owing, in part, to the fact that it does not allow for full inspection of the lacrimal sac or biopsies of atypical findings to be taken19,20,22,23.
In terms of functional success, it ranges closely behind the current gold standard of external DCR with early functional success rates of 74 - 85% at one-year follow-up 10,11,12,13,14,15,16,17,18,19 for the transcanalicular approach compared to &#62;85% for external DCR2,3,19. However, studies providing long term results are somewhat scarce. In one study, Kaynak et al. found that functional success rates of laser-assisted DCR can drop to 63% within the first year and further drop to 60% within the first two years24. In contrast, Dogan et al. found functionally successful results in up to 84% of cases over a mean follow-up time of 18.1 months17. The relatively wide range of outcomes may be due to the fact that laser-assisted DCR is not yet a standardized technique and most protocols found in literature show certain fundamental differences. These differences encompass varying laser settings and wavelengths, Teflon vs. silicon intubation, local vs. general anaesthesia and the additional use of adjuvant substances like mitomycin C (MMC) or endonasal trephination15,17,25,26,27,28. Compared to external DCR, complication rates in laser-assisted DCR are relatively low and duration of surgery as well as reconvalescence is kept to a minimum10.
In order to improve functional success rates, a number of additional steps have been proposed, adding to the mere formation of a lacrimal bypass. For one thing, in the above mentioned protocol, bicanalicular silicon intubation is included to facilitate epithelization of the bypass and prevent early scarring of the newly formed osteotomy10,11,12,13,14,15,16. This step (as either monocanalicular or bicanalicular intubation) is commonly used in a variety of protocols and techniques including external DCR2,3,19. However, the data found on this matter in current literature is conflicting and no consensus on whether patients benefit from silicon intubation in lacrimal bypass surgery has been reached to date25,26.
Furthermore, to inhibit scarring of the osteotomy, the topical application of the antimetabolite mitomycin C, known for its use in glaucoma surgery, has been proposed. Several studies investigating the alleged profit of additional topical MMC application to the bypass right after osteotomy could not show a significant advantage of this adjunctive procedure17,27,28.
The most critical step in the provided protocol is the correct formation of a sufficient osteotomy in the optimal location. When inserting the laser fiber optic, it is recommended to take the approach via the lower canaliculus as this will grant the highest maneuverability later. In a recent study of laser-assisted DC10,11, the laser fiber was advanced through the upper canaliculus in 20 of the participating patients. In three of those, correct positioning of the laser proved impossible due to prominence of the upper orbital rim, in turn leading to unfavorable positioning of the osteotomy later. Furthermore, after successful positioning of the tip and before applying energy to the lateral nasal wall, it is of paramount importance to ensure the tip has not slid back into the cannula. In one reported case10,11, retraction of the tip resulted in heating of the metal cannula, which in turn led to thermal injury that required plastic reconstruction.
It is important to note that the osteotomy created with a 300 - 400 &#181;m diode laser fiber is markedly smaller than that of a drill in external DCR. After enlargement of the osteotomy as described above, ostium diameters of up to 5 mm can be achieved. However, the ostium diameter in external DCR ranges around 1 cm. Logically, a bigger osteotomy is less susceptible to early scarring. It is therefore recommended to aim for as big an ostium as possible while at the same time avoiding unnecessary tissue damage. It has to be noted that the induction of fibrosis as a late complication of the laser procedure is possible. However, the degree to which this happens cannot be estimated yet.
In summary, transcanalicular laser-assisted DCR, if performed as delineated above, provides good results as a viable option before invasive lacrimal surgery in cases of PANDO. Because of low complication rates and short convalescence and surgery time, patient satisfaction is high, while at the same time, functional success rates range closely behind those of external DCR.

Infrasaccal primary acquired nasolacrimal duct obstruction (PANDO) is a common disorder in middle-aged and older patients leading to chronic epiphora and blepharitis as well as recurring or chronic dacryocystitis. Most commonly, patients develop an infrasaccal obstruction of one or both nasolacrimal ducts, resulting in insufficient tear drainage.
In the treatment of PANDO, external dacryocystorhinostomy (DCR) is still considered to be the gold standard, even though this procedure historically dates back over a hundred years to when it was first performed1. After skin incision and preparation of the nasal wall of the lacrimal sac, a drill is used to create a bony ostium leading to the nasal cavity, thus bypassing the obstructed duct. Functional success rates above 85% have been reported for this method2,3. These results, however, come at the cost of performing a relatively invasive procedure that puts at risk the medial structures of the eyelid including the physiological canalicular pump mechanism4,5 and may leave patients with an unwelcome scar, although modern nasojugal skin incisions have improved results. These risks are potentially avoidable by performing less invasive techniques or choosing an endonasal approach.
In order to circumvent invasive surgery, much work has been done in the field of minimally invasive tear drainage recanalization. Two methods in particular have been established as potential first-step procedures: microdrill dacryoplasty and laser-assisted dacryoplasty. These procedures are based on transcanalicular endoscopy of the tear drainage system and can be performed to treat for short-segment membranous stenoses of the nasolacrimal duct. Though only minimally invasive and characterized by quick reconvalescence, a common drawback of these recanalizing techniques are the relatively low functional success rates with regard to long-term outcomes6,7,8,9.
In an effort to fill the void between these first-step procedures and external DCR as a definitive treatment, new approaches have recently been developed. The most promising of which is laser-assisted DCR for the treatment of absolute infrasaccal PANDO. Like with all aforementioned approaches, patients are recommended to be put under general anesthesia for this procedure. A diode laser fiber is inserted via either canaliculus and is then advanced into the lacrimal sac. Next, laser energy is applied to the lateral nasal wall until a bony ostium is created, connecting to the nasal cavity at the height of the middle turbinate&#39;s anterior margin10,11. All the while, constant visual control is kept using endonasal endoscopy. The newly formed anastomosis serves as a bypass for the tear drainage. After successful irrigation, bicanalicular silicon intubation is performed to prevent early scarring of the newly formed ostium. Postoperative treatment consists of decongestant, steroidal and antibiotic eye drops to prevent swelling, inflammation, and infection, respectively.
The duration of surgery as well as reconvalescence is generally shorter than with external DCR (10 - 25 min in laser-assisted DCR vs. 35 - 75 min in external DCR). Complication rates are relatively low, the most common being discrete swelling of the eyelids and silicon tube prolapse. Canalicular infection and thermal injury are rare events10. One-year functional success rates of 74 - 88% have been reported10,11,12,13,14,15,16,17,18, thus ranging closely behind those of external DCR without suffering the disadvantages of the external surgical approach. However, long-term results remain yet to be provided. Additionally, even after failure of laser-assisted DCR, secondary external DCR can still be performed without difficulty. Consequently, laser-assisted DCR qualifies as a viable second-step procedure that should optimally be performed after failure of recanalization surgery and before external DCR.

<table><tbody><tr><td>C1.multi</td><td>LUT</td><td>05.0082h.1</td><td>Endoscope camera</td></tr><tr><td>HL 250</td><td>LUT</td><td>95.2048n</td><td>Endoscope light source</td></tr><tr><td>MD-19E</td><td>ACL GmbH</td><td>1119</td><td>Endoscope screen</td></tr><tr><td>FOX (laser)</td><td>A.R.C. Laser GmBH, N&amp;uuml;rnberg, Germany</td><td>n/a</td><td>Diode laser</td></tr><tr><td>Laser fiber</td><td>A.R.C. Laser GmBH, N&amp;uuml;rnberg, Germany</td><td>LL13001s</td><td>Laser fiber</td></tr><tr><td>Laser handpiece</td><td>A.R.C. Laser GmBH, N&amp;uuml;rnberg, Germany</td><td>n/a</td><td>Handpiece</td></tr><tr><td>Wide Collarette Monoka</td><td>Fa. FCL, Paris, France</td><td>S1.1630</td><td>monocanalicular silicon tube</td></tr><tr><td>Suction elevatorium</td><td>Storz</td><td>474015</td><td>For intranasal use</td></tr><tr><td>Forceps (Gr&amp;uuml;nwald)</td><td>Storz</td><td>426620</td><td>For intranasal use</td></tr><tr><td>Forceps (Blakesley-Wilde)</td><td>Storz</td><td>456502</td><td>To grab the silicon tube</td></tr><tr><td>Lacrimal canula</td><td>Storz</td><td>81071</td><td>Blunt cannula</td></tr><tr><td>Bangerter probe cannula</td><td>Storz</td><td>81055</td><td>Bangerter probe cannula</td></tr><tr><td>Wooden spatula</td><td>any</td><td>n/a</td><td>Wooden spatula</td></tr><tr><td>Xylometazolin 0.05% eye drops</td><td>GlaxoSmithKline Consumer Healthcare</td><td>n/a</td><td>Decongestant eye drops</td></tr><tr><td>Dexapos comod eye drops</td><td>Ursapharm</td><td>n/a</td><td>steroid eye drops</td></tr><tr><td>Floxal eye drops</td><td>Dr. Gerhard Mann</td><td>n/a</td><td>antibiotic eye drops</td></tr></tbody></table>

transcanalicular diode laser-assisted dacryocystorhinostomy for the treatment of primary acquired nasolacrimal duct obstruction

Today&#39;s gold standard in the treatment of infrasaccal primary acquired nasolacrimal duct obstruction (PANDO) is external dacryocystorhinostomy (DCR), a relatively invasive procedure that can be performed after failure of recanalizing treatments. However, with progress in the field of diode laser technology, new approaches have emerged. Laser-assisted transcanalicular DCR with subsequent bicanalicular silicon intubation is a new option showing great promise as a viable minimally invasive procedure. Under permanent endoscopic visual control from the nasal cavity, a diode laser fiber is inserted into the lacrimal sac and laser energy is applied to create a bony ostium between the lacrimal sac and the nasal cavity. Since no skin incision needs to be made, advantages of this method comprise the sparing of the skin as well as the medial palpebral structures and the physiological palpebral-canalicular pump mechanism. The duration of surgery as well as reconvalescence is generally shorter than with external DCR. Complications include silicon tube prolapse, mild swelling and, rarely, canalicular infection and thermal injury. One-year functional success rates, defined as complete resolution of symptoms and ostium patency, are high, yet still range behind those of external DCR. However, secondary external DCR after failure of laser-assisted DCR can be performed without difficulty. Thus, laser-assisted transcanalicular DCR is a valid option that should be considered as a second-step procedure after failure of recanalization procedures and before external DCR.

Optimal result:
The procedure as described above takes about 10 - 25 min and is usually tolerated very well. Upon examination the next day, a little swelling of the eyelid can be present in about 60% of cases. This little swelling always resolves completely within a maximum of three days. Patients do not complain about pain, silicon prolapse or signs of injury or infection. However, due to bicanalicular silicon intubation being performed during the procedure, epiphora may persist until the tubes are removed. Topical application of antibiotic, steroidal, and decongestant eye postoperatively is essential and patients need to follow instructions closely for optimal results. At three months after surgery, silicon tubes can be removed easily. In optimal cases, complete and permanent resolution of symptoms can be observed. Table 1 gives an overview of the results of this technique, previously published by Koch et al. in 201610.
Sub-optimal results:
Although relief of symptoms initially occurs in most patients, about 20 - 25% of patients, who have otherwise had little to no complications, show incomplete resolution of symptoms at the six-months mark. The most likely reason for this is scar tissue forming in the bony ostium. In these cases of recurring stenosis, secondary external DCR can become necessary.
Complicated cases:
Serious complications are rare. When the utilized laser equipment is not handled carefully, the tip of the laser fiber can slip back into the metal cannula which will cause heating of the metal. This results in thermal injury to the canaliculus or lacrimal sac. Penetrating injuries due to necrosis of the tear drainage system require suturing and, possibly, a displacement flap to close the defect. Affected patients need to be followed up more closely as the lesion facilitates scarring and an ensuing obstruction as well as infections. Secondary external DCR and canaliculus reconstruction surgery can become necessary in these cases.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/55981/55981fig1.jpg" /> 
Figure 1. Pre- and postoperative portrait photos of a 73-year-old patient who underwent transcanalicular laser-assisted DCR of the left side. 
a Preoperative appearance. b Mild swelling of the lower eyelid on the first postoperative day, resolving completely within two days. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55981/55981fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/55981/55981fig2.jpg" /> 
Figure 2. Experimental Walkthrough 
a. Dilation of the upper punctum using a lacrimal probe. Dilation has to be performed bicanalicularly to facilitate silicon intubation later. 
b. The laser fiber is inserted into the handpiece and the blunt cannula. Subsequently, it is inserted into the lower canaliculus. 
c. Correct placement of the laser fiber. After inserting the cannula, the tip is pointing in an antero-inferior direction, aiming for the anterior margin of the middle turbinate. 
d. The aiming beam of the laser appears approximately at the anterior margin of the middle turbinate. Laser energy is applied to create an ostium. 
e. As the tissue between the lacrimal sac and the nasal cavity grows thinner, the light becomes brighter. Breaching of the wall is imminent. 
f. Shortly after breaching the wall. The tip of the laser fiber can be seen sticking through the newly formed osteotomy. 
g. Silicon intubation of the lower canaliculus. 
h. Intranasal image during silicon intubation of the upper canaliculus. The first silicon tube is already in place (lateral side) while the leading metal tip of the second silicon tube is sticking out of the ostium. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55981/55981fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>number of patients</td>
			<td>48</td>
		</tr>
		<tr>
			<td>male</td>
			<td>11</td>
		</tr>
		<tr>
			<td>female</td>
			<td>37</td>
		</tr>
		<tr>
			<td>mean age (years)</td>
			<td>60 &#177; 11</td>
		</tr>
		<tr>
			<td>surgical success rate*</td>
			<td>94%</td>
		</tr>
		<tr>
			<td>functional success rate (6 months)**</td>
			<td>78%</td>
		</tr>
		<tr>
			<td>postoperative lid swelling</td>
			<td>64%</td>
		</tr>
		<tr>
			<td>canalicular infection</td>
			<td>2%</td>
		</tr>
		<tr>
			<td>thermal injury</td>
			<td>2%</td>
		</tr>
		<tr>
			<td>silicon tube prolapse</td>
			<td>9%</td>
		</tr>
		<tr>
			<td>* defined as postoperative bypass patency</td>
			<td></td>
		</tr>
		<tr>
			<td>**defined as complete resolution of symptoms</td>
			<td></td>
		</tr>
	</tbody>
</table>
Table 1. 
Overview of the results of laser-assisted DCR as described in this protocol. Data previously published in Klin. Monbl. Augenheilkd. by Koch et al. in 201610.

Watch this Scientific Journal Video about Transcanalicular Diode Laser-assisted Dacryocystorhinostomy for the Treatment of Primary Acquired Nasolacrimal Duct Obstruction at JoVE.com

Transcanalicular Diode Laser-assisted Dacryocystorhinostomy for the Treatment of Primary Acquired Nasolacrimal Duct Obstruction

The goal of this protocol is to present transcanalicular laser-assisted dacryocystorhinostomy as a minimally invasive approach in the treatment of primary acquired nasolacrimal duct obstruction.

Today&#39;s gold standard in the treatment of infrasaccal primary acquired nasolacrimal duct obstruction (PANDO) is external dacryocystorhinostomy (DCR), ...

transcanalicular-diode-laser-assisted-dacryocystorhinostomy-for

Nanyang Technological University

Research

JoVE Journal

Medicine

11.0K Views.  University of Cologne. Het doel van dit protocol is te transcanalicular laser-assisted dacryocystorhinostomy presenteren als een minimaal invasieve benadering in de behandeling van primaire verworven nasolacrimal duct obstructie.

Video: Transcanalicular Diode Laser-assisted Dacryocystorhinostomy for the Treatment of Primary Acquired Nasolacrimal Duct Obstruction

Canalostomy As a Surgical Approach to Local Drug Delivery into the Inner Ears of Adult and Neonatal Mice

Local delivery of therapeutic drugs into the inner ear is a promising therapy for inner ear diseases. Injection through semicircular canals (canalostomy) has been shown to be a useful approach to local drug delivery into the inner ear. The goal of this article is to describe, in detail, the surgical techniques involved in canalostomy in both adult and neonatal mice. As indicated by fast-green dye and adeno-associated virus serotype 8 with the green fluorescent protein gene, the canalostomy facilitated broad distribution of injected reagents in the cochlea and vestibular end-organs with minimal damage to hearing and vestibular function. The surgery was successfully implemented in both adult and neonatal mice; indeed, multiple surgeries could be performed if required. In conclusion, canalostomy is an effective and safe approach to drug delivery into the inner ears of adult and neonatal mice and may be used to treat human inner ear diseases in the future.

Here we describe canalostomy procedure which allows local drug delivery into the inner ears of adult and neonatal mice through the semicircular canal with minimum damage to hearing and vestibular function. This method can be used to inoculate viral vectors, pharmaceuticals, and small molecules into the mouse inner ear.

Local delivery of therapeutic drugs into the inner ear is a promising therapy for inner ear diseases. Injection through semicircular canals (canalostomy) ...

Genetics

Ultrasound Cyclo Plasty in Eyes with Glaucoma

Glaucoma is a chronic disease caused by the progressive degeneration of the optical nerve fibers, resulting in decreased visual field that can lead to severe visual impairment, and eventually blindness. This manuscript describes a simple, surgeon-friendly, non-incisional technique, named Ultrasound Cyclo Plasty (UCP), for reducing intraocular pressure (IOP) in glaucoma patients. The technique determines a selective coagulation necrosis of the ciliary body; in addition, the stimulation of supra-choroidal and trans-scleral portions of the uveo-scleral outflow pathway has been recently proposed. UCP shows several technical improvements in ultrasound technology compared to previous techniques, providing more precise focusing on the target zone. The procedure is performed in the operating room under peribulbar anesthesia. Briefly, the coupling cone is put in contact with the eye and the ring probe, that contains six piezoelectric transducers which produce the ultrasound beams, is inserted inside it. Their proper centering over the ocular surface represents a crucial step for the correct targeting of the ciliary body. Sterile balanced salt solution is used to fill the empty spaces to ensure ultrasound acoustic propagation. Surgical treatment consists in the sequential automatic activation of each of the six transducers, for a total duration of less than 3 min. The patient leaves the hospital 1 h after the procedure with the treated eye patched. In the present study, 10 patients with open-angle glaucoma were followed-up during at least 12 months after the procedure. IOP was reduced at each interval compared to pre-operative, as well as the number of hypotensive medications. Twenty percent of patients did not respond to the treatment, and needed subsequent surgery to better control IOP. Treatment tolerability was good, with no cases of hypotony or phthisis. The UCP procedure is simpler, faster, safer, and less invasive than traditional cyclodestructive procedures with similar results in reducing IOP.

Glaucoma is a chronic disease with progressive degeneration of optic nerve fibers resulting in decreased visual field. Elevated intraocular pressure is considered the most important and the only treatable risk factor. This manuscript describes a simple, surgeon-friendly, non-incisional technique, named Ultrasound Cyclo Plasty, for reducing intraocular pressure in glaucoma patients.

Glaucoma is a chronic disease caused by the progressive degeneration of the optical nerve fibers, resulting in decreased visual field that can lead to ...

Behavior

Surgical Induction of Endolymphatic Hydrops by Obliteration of the Endolymphatic Duct

Surgical induction of endolymphatic hydrops (ELH) in the guinea pig by obliteration and obstruction of the endolymphatic duct is a well-accepted animal model of the condition and an important correlate for human Meniere's disease. In 1965, Robert Kimura and Harold Schuknecht first described an intradural approach for obstruction of the endolymphatic duct (Kimura 1965). Although effective, this technique, which requires penetration of the brain's protective covering, incurred an undesirable level of morbidity and mortality in the animal subjects. Consequently, Andrews and Bohmer developed an extradural approach, which predictably produces fewer of the complications associated with central nervous system (CNS) penetration.(Andrews and Bohmer 1989) 
The extradural approach described here first requires a midline incision in the region of the occiput to expose the underlying muscular layer. We operate only on the right side. After appropriate retraction of the overlying tissue, a horizontal incision is made into the musculature of the right occiput to expose the right temporo-occipital suture line. The bone immediately inferio-lateral the suture line (Fig 1) is then drilled with an otologic drill until the sigmoid sinus becomes visible. Medial retraction of the sigmoid sinus reveals the operculum of the endolymphatic duct, which houses the endolymphatic sac. Drilling medial to the operculum into the area of the endolymphatic sac reveals the endolymphatic duct, which is then packed with bone wax to produce obstruction and ultimately ELH. 
In the following weeks, the animal will demonstrate the progressive, fluctuating hearing loss and histologic evidence of ELH.

This video shows how to surgically obstruct the guinea pig's endolymphatic duct to produce endolymphatic hydrops.

Surgical induction of endolymphatic hydrops (ELH) in the guinea pig by obliteration and obstruction of the endolymphatic duct is a well-accepted animal ...

Biology

An &#8220;All-laser&#8221; Endothelial Transplant

The &#8220;all laser&#8221; assisted endothelial keratoplasty is a procedure that is performed with a femtosecond laser used to cut the donor tissue at an intended depth, and a near infrared diode laser to weld the corneal tissue. The proposed technique enables to reach the three main goals in endothelial keratoplasty: a precise control in the thickness of the donor tissue; its easy insertion in the recipient bed and a reduced risk of donor lenticule dislocation. The donor cornea thickness is measured in the surgery room with optical coherence tomography (OCT), in order to correctly design the donor tissue dimensions. A femtosecond laser is used to cut the donor cornea. The recipient eye is prepared by manual stripping of the descemetic membrane. The donor endothelium is inserted into a Busin-injector, the peripheral inner side is stained with a proper chromophore (a water solution of Indocyanine Green) and then it is pulled in the anterior chamber. The transplanted tissue is placed in the final and correct location and then diode laser welding is induced from outside the eyeball. The procedure has been performed on more than 15 patients evidencing an improvement in surgery performances, with a good recovery of visual acuity and a reduced donor lenticule dislocation event.

An all laser procedure is proposed in the endothelial transplant. The surgical technique is based on the use of a femtosecond laser to prepare the donor tissue. Laser welding technique is then used to secure the donor endothelium in the correct position.

The &#8220;all laser&#8221; assisted endothelial keratoplasty is a procedure that is performed with a femtosecond laser used to cut the donor tissue at an ...

Establishment of a Severe Dry Eye Model Using Complete Dacryoadenectomy in Rabbits

Dry eye disease (DED) is a complex disease with multiple etiologies and variable symptoms, having ocular surface inflammation as its key pathophysiologic step. Despite advances in our understanding of DED, significant knowledge gaps remain. Advances are limited in part due to the lack of informative animal models. The authors recently reported on a method of DED induced by injecting all orbital lacrimal gland (LG) tissues with the lectin concanavalin A. Here, we report a novel model of aqueous-deficient DED based on the surgical resection of all orbital LG (dacryoadenectomy) tissues. Both methods use rabbits because of their similarity to human eyes in terms of the size and structure of the ocular surface. One week after removal of the nictitating membrane, the orbital superior LG was surgically removed under anesthesia, followed by removal of the palpebral superior LG, and finally removal of the inferior LG. Dacryoadenectomy induced severe DED, evidenced by a marked reduction in the tear break up time test and the Schirmer&#39;s tear test, and significantly increased tear osmolarity and rose bengal staining. Dacryoadenectomy-induced DED lasted at least eight weeks. There were no complications and animals tolerated the procedure well. The technique can be mastered relatively easily by those with adequate surgical experience and appreciation of the relevant rabbit anatomy. Since this model recapitulates the features of human aqueous-deficient DED, it is suitable for studies of ocular surface homeostasis, DED, and candidate therapeutics.

A novel approach is presented to induce chronic dry eye disease in rabbits by surgically removing all orbital lacrimal glands. This method, distinct from those previously reported, produces a stable, reproducible model of aqueous deficient dry eye well suited to study tear physiology and pathophysiology and ocular therapeutics.

Dry eye disease (DED) is a complex disease with multiple etiologies and variable symptoms, having ocular surface inflammation as its key pathophysiologic ...

Endaural Endoscopic Atticoantrotomy (Retrograde Mastoidectomy) using a Constant Suction Bone-drilling Technique

Endoscopic middle ear surgery is a widely employed minimally invasive surgical technique to address middle ear and mastoid pathology. Bone drilling is the main technical challenge of endoscopic middle ear surgery. The accompanying video describes the detailed protocol of a constant-suction bone-drilling technique and the procedure of endaural exclusive endoscopic atticoantrotomy (retrograde mastoidectomy) using this technique. The main components of this bone-drilling technique include a soft and flexible suction tube, which is placed into the tympanic cavity to provide constant suction, and a soft sleeve, which is wrapped around the drill shaft to prevent the high-speed rotating shaft from damaging the lens of the endoscope. With these simple modifications, the traditional otological electrodrill can be used for drilling a tiny endaural incision in endoscopic middle ear surgery. Based on this bone-drilling technique, endaural endoscopic atticoantrotomy (retrograde mastoidectomy) can be successfully established for the removal of various amounts of bone, depending on the extent of the lesion. The short-term postoperative outcome seems promising.

Endaural Endoscopic Atticoantrotomy Retrograde Mastoidectomy using a Constant Suction Bone-drilling Technique

In this paper, we present the protocol and short-term outcomes of endaural exclusive endoscopic atticoantrotomy using a constant suction bone-drilling technique.

Endoscopic middle ear surgery is a widely employed minimally invasive surgical technique to address middle ear and mastoid pathology. Bone drilling is the ...

The Microscopic Transcanal Approach in Stapes Surgery Revisited

The microscopic transcanal (aka transmeatal) surgical approach was first described in the 60s, offering a minimally invasive means of reaching the external auditory canal, the middle ear, and epitympanon. Such an approach avoids a retroauricular or endaural skin incision; however, working through a narrow space needs angled microsurgical instruments and specific training in otologic surgery. The transcanal approach restricts the working space; however, it offers a binocular microscopic vision into the middle ear without extended skin incisions and thus, reducing post-operative pain and bleeding. In addition, this minimally invasive approach avoids scar tissue complications, hypoesthesia of the auricle, and potential protrusion of the pinna. Despite its numerous advantages, this method is still not routinely performed by otologic surgeons. Since this minimally invasive technique is more challenging, there is a need for extensive training in order for it to be widely adopted by otologic surgeons. This article provides step-by-step surgical instructions for stapes surgery and reports possible indications, pitfalls, and limitations using this microscopic transcanal technique.

This article describes the microscopic transcanal technique for stapes surgery, providing step-by-step surgical instructions for familiarizing surgeons with this approach.

The microscopic transcanal (aka transmeatal) surgical approach was first described in the 60s, offering a minimally invasive means of reaching the ...

Endolymphatic Duct Blockage as a Surgical Treatment Option for M&#233;ni&#232;re's Disease

Endolymphatic duct blockage is a relatively new treatment option for M&#233;ni&#232;re's disease, aiming to reduce vertigo attacks while sparing hearing and equilibrium. After a regular mastoidectomy, the posterior semicircular canal is identified, and Donaldson's line is determined. This is a line through the horizontal semicircular canal, crossing the posterior semicircular canal. The endolymphatic sac is usually found at this site under the posterior semicircular canal. The bone of the endolymphatic sac and the dura are thinned until the sac is skeletonized, after which the endolymphatic duct is identified. The duct is then blocked with a titanium clip. Using a computerized tomography (CT) scan, the position is confirmed. Follow-up visits take place 1 week, 6 weeks and 1 year after surgery. To this day, only one prospective trial assessing this method has been conducted, comparing this new method to endolymphatic sac decompression. Results of the duct blockage are promising, with 96.5% of the patients free of vertigo after 2 years. However, further research is required.

Endolymphatic duct blockage is a relatively new surgical method for patients suffering from M&#233;ni&#232;re's disease. Following a regular mastoidectomy, the endolymphatic duct is identified and ligated using a regular titanium hemoclip. The effectiveness of this procedure is currently being assessed in a randomized trial.

Endolymphatic duct blockage is a relatively new treatment option for M&#233;ni&#232;re's disease, aiming to reduce vertigo attacks while sparing hearing ...

Robot-Assisted Transcanal Endoscopic Ear Surgery for Congenital Cholesteatoma

Congenital cholesteatoma accounts for 25% of cholesteatoma cases in children. Transcanal Endoscopic Ear Surgery (TEES) is ideal for these patients because it offers a wide endoscopic view of the middle ear and a minimally invasive approach. The two main limitations are the loss of one operative hand and a narrow external auditory canal in younger children. Here, we present the case of a 3-year-old patient with a Potsic stage III congenital cholesteatoma adherent to the incus and branches of the stapes. A robotic-assisted TEES procedure was performed, during which a robotic arm with 6 degrees of freedom held a 0&#176;, 2.9 mm wide endoscope, enabling the surgeon to work in a narrow environment with both hands. The procedure's duration was 2 h and 9 min, including 16 min for the installation and draping of the robotic arm. After a trans-canal approach, the cholesteatoma was dissected from the ossicles using both a needle (or sickle knife) and suction to stabilize the ossicles and limit the risk of hearing trauma. The cholesteatoma was debulked to reduce its size, allowing it to be pushed under the malleus anteriorly and then separated from other adherences before removal. A tragal cartilage graft was used to reinforce the tympanic membrane.

This protocol describes the removal of congenital cholesteatoma using minimally invasive transcanal endoscopic ear surgery with a two-handed approach and a robotic endoscope holder.

Congenital cholesteatoma accounts for 25% of cholesteatoma cases in children. Transcanal Endoscopic Ear Surgery (TEES) is ideal for these patients because ...

Nasolacrimal Lavage as a Treatment for Ocular Surface Toxic Soup Syndrome

Ocular surface toxic soup syndrome (OSTSS) is characterized by inadequate tear drainage through the nasolacrimal duct system, leading to the accumulation of inflammatory mediators in the tear film. This condition can result in toxic keratoconjunctivitis, with symptoms such as conjunctival hyperemia, itchiness, discomfort, and epiphora. Dilation and irrigation are common diagnostic procedures in both optometry and ophthalmology, used to assess nasolacrimal duct obstruction in cases of epiphora. This technique involves the injection of saline into the nasolacrimal duct system through the puncta, followed by the evaluation of reflux, which indicates obstruction. Although intended to be diagnostic, many patients report significant improvements in epiphora and ocular comfort after the procedure. In this paper, we present a case study in which a patient achieved complete resolution of epiphora and itchiness following therapeutic nasolacrimal lavage performed every 2 months. Subjective improvements in symptoms in 3 additional patients are also reported. We propose nasolacrimal lavage not only as a diagnostic tool but also as an effective therapeutic intervention for managing OSTSS.

OSTSS leads to pooled inflammatory mediators in the tear film, causing symptoms like epiphora and discomfort. Here, we present a case where therapeutic nasolacrimal lavage every 2 months resolved epiphora and itchiness, suggesting its efficacy as a therapeutic intervention for OSTSS. Additionally, we report subjective improvements in symptoms in 3 additional patients.

Ocular surface toxic soup syndrome (OSTSS) is characterized by inadequate tear drainage through the nasolacrimal duct system, leading to the accumulation ...

Transcanalicular Diode Laser-assisted Dacryocystorhinostomy for the Treatment of Primary Acquired Nasolacrimal Duct Obstruction

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