Dacryocystorhinostomy (DCR) is a procedure wherein an alternate passage is created between the lacrimal sac and nasal mucosa through a bony ostium, bypassing the normal lacrimal pathway.
1. Persistent congenital lacrimal duct obstruction unresponsive to conservative management.
2. Primary acquired nasolacrimal duct obstruction (PANDO).
3. Secondary acquired nasolacrimal duct obstruction (SALDO).
DCR can be classified as either external or internal. In external DCR the bone of lacrimal sac fossa is accessed through a cutaneous incision over the medial canthus. In internal DCR the normal openings around the lacrimal outflow system ( puncta, canaliculus, nasal cavity) are utilized to create the passage between the lacrimal sac and nasal cavity, without any skin incision. Internal DCR is most commonly performed through an endonasal approach and can be performed by using roungers, drills and even lasers. Endonasal DCR s can be performed either under endoscopic guidance or under direct illumination. DCR s performed through puncta (transcanalicular DCR) utilize different types of lasers to open up the sac mucosa, bone of lacrimal sac fossa and finally the nasal mucosa to create the ostium. Following flow chart illustrates the different types performed to create an alternative lacrimal outflow pathway.
The following table provides success rates of different DCR techniques.
Tsirbas A, et al. OPRS. 2004;20:50-56.
Non endoscopic endonasal DCR
Razavi ME, et al. Orbit. 2009;28:1-6.
Endoscopic endonasal DCR
Tsirbas A, et al. OPRS. 2004;20:50-56.
Transcanalicular laser DCR
Piaton JM, et al. J Fr Ophtalmol 2001;24:253–264
The following are some of the conditions where an external DCR is best avoided.
1. Acute dacryocystitis (an indication for endonasal DCR).
2. Lacrimal sac neoplasm.
3. Adnexal neoplasm involving the sac
4. Traumatic NLDO causing severe disruption of anatomical landmarks.
5. Allergic rhinitis
6. Rhinosporidiosis of the lacrimal sac
7. Advanced age and age less than 1 year
ROPLAS (Regurgitation On Pressure over Lacrimal Sac).A ROPLAS positive patient is a case of nasolacrimal duct obstruction beyond doubt. To perform a correct ROPLAS follow the infraorbital rim to reach up to anterior lacrimal crest and then press just medially and posteriorly so that the sac gets pressed. A negative ROPLAS will many a times not preclude the diagnosis of NLDO. Following are some of the variations of this sign.
1. A patient can be ROPLAS positive even in the presence of a patent lacrimal system in cases of sump syndrome.
2. In cases of contracted sac and encysted mucoele ROPLAS can be negative even in the presence of NLDO.
3. Many patients have a habit of emptying the sac on regular intervals by performing self ROPLAS, these cases can also mislead the clinician with ROPLAS being negative.
Syringing:Syringing of the lacrimal system is an anatomical test to determine if an obstruction exists within the system. Syringing is generally done from the lower punctum, using a 23” canula attached to a 3 cc syringe, after dilating the punctum by a punctum dilator. The lower lid is put on a stretch by pulling the lid laterally. This is done to straighten the canaliculus and thus avoiding any false passage. The end of the canula is inserted 4 mm inside the lower punctum and then the fluid is irrigated. One of the three results may be found on syringing.
1. Fluid passes into nose and throat (patent lacrimal system).
2. Fluid regurgitates through the canaliculus, common canaliculus, and sac and comes out through the upper punctum.
3. Fluid comes directly back through the lower canaliculus.
There may be a combination of any two or even three of these findings.
Probing:Situation 2 in syringing can arise either due to a block at the level of NLD, lacrimal sac or common canaliculus, while situation 3 indicates a block of the individual canalicular system (upper and lower). The dilemma of situation 2 can be solved by passing a Bowmann’s lacrimal probe through the canaliculus (canalicular palpation). A “hard stop” on canalicular palpation indicates a block at the level of NLD or lacrimal sac while a soft stop indicates a common canalicular block. In situation 3 the probe is passed into the canalicular system and an artery forceps can be placed against the punctum on the probe, the probe is slowly withdrawn and the distance from the probe end to the artery forceps is measured. A block up to 6 mm into the canalicular system is defined as a proximal canalicular block, while any block beyond 6 mm is defined as distal canalicular block.
Dacryocystography (DCG):Dacryocystography is the most definitive test for assessing the anatomy of the nasolacrimal drainage system. It is performed by irrigating the nasolacrimal system by a radiopaque dye through the puncta. The dye flowing through the nasolacrimal system can then be visualized either by a roentgenogram (X-ray) or by a CT scan. A CT DCG is preferred nowadays owing to its ability to provide finer details of the surrounding bony anatomy. A DCG is indicated in the following situations.
1. Difficulty in determining whether there is a “hard stop” or a “soft stop”.
2. Traumatic NLDO.
3. Failed lacrimal surgery.
4. In canalicular obstruction where canaliculitis is suspected, a DCG will show an enlarged canaliculus.
5. Partial obstructions.
6. Patients suspected to have dacryoliths.
7. Patients with suggested lacrimal sac tumors.
8. Patients presenting with epiphora after a nose, sinus, or orbital surgery.
Nasal examination: a routine nasal examination by anterior rhinoscopy in the clinic followed by a nasal endoscopic examination should be carried out in every case to rule out any associated nasal pathology.
Hematological investigations: these include a hemoglobin level, blood sugar (fasting and postprandial), and a coagulation profile (BT, CT, APTT)
Control of BP: A preoperative measurement of blood pressure and its adequate control is essential before taking up the case for an external DCR. There are more chances of pre-op and post-op bleeding in cases of uncontrolled high blood pressure.
Stoppage of blood-thinning agents:Proper history should be taken about the patient being on any blood thinners (e.g aspirin, clopidogrel, warfarin). The patient should be advised to abstain from these drugs according to the following protocol under the advice of the concerned physician.
1. Aspirin: 10 - 14 days before surgery.
2. Warfarin: 5 days before surgery
3. NSAID: 3 days before surgery
It is better to shift any patient on warfarin to heparin, as heparin has a half-life of 5 hours.
Pre-op nasal decongestantsin the form of 0.05% xylometazoline nasal drops should be prescribed to all patients at least 2 days before surgery. The patient should also be started on topical antibiotic eye drops.
Local Vs General anesthesia:External DCR is most commonly performed under local anesthesia. General anesthesia has the advantage of airway control as well as blood pressure control. General anesthesia is indicated in very young, uncooperative, extremely nervous and anxious patients. It is also advisable to undertake cases of traumatic NLDO under general anesthesia. While maintaining hypotension it is prudent to limit the induced hypotension to 70% of the patient’s original systolic and diastolic blood pressure.
Local infiltration for external DCR: After proper sedation following areas need to be addressed for appropriate local anesthesia.
1.Infratrochlear nerve block:Infratrochlear nerve can be reached by injecting through the skin in a posterior direction just superior to the anterior limb of the medial canthal tendon. The patient’s vision should be checked periodically as there are chances of involving some vessels causing bleeding. It is better to avoid this block in one-eyed patients.
2.Subcutaneous injection in the sac area:With the needle still in place after injecting the infra trochlear block, its direction is changed and now the incision site is infiltrated right up to the periostium of anterior lacrimal crest. It is mandatory to withdraw the plunger before injecting it to make sure one is not in the angular vein.
3.Peri infraorbital nerve injection:The area around the infraorbital rim at the junction of lateral 2/3rd and medial 1/3rd is pierced subcutaneously and the needle is advanced towards the nose till it hits the side of the nose. The plunger is then withdrawn to make sure that one has not entered the angular vein, and a bolus of local anesthesia is then slowly injected on withdrawal till the needle comes out of the tissue plane. The area is then pressed to help the anesthetic agent diffuse around the infraorbital nerve.
The positioning of the patient:The patient is placed in a reverse Trendelenburg position (head up feet down position). This position facilitates venous drainage from the head and neck region thereby reducing bleeding.
Prerequisites:The following are some of the prerequisites which reduce the surgeon’s anxiety and bring considerable peace in the operating room thereby aiding in the success of the surgery.
1.Surgical loupe:A good surgical loupe provides appropriate magnification and helps in having a better view of a surgical site where everything is practically maneuvered through a keyhole.
2.Illumination:Adjusting illumination according to the surgeon’s requirement is a challenge especially with the routine operating room light, as the person adjusting illumination doesn’t have a clear idea exactly where the light should fall. Fiber optic illumination and illumination mounted on the surgeon’s surgical loupe give the best visualization of the operating field.
3.Cautery and suction:A bipolar cautery is mandatory for external DCR. The need for a proper suction with spare suction tips (to be used in case the previous one clogs) can’t be overemphasized. Both these instruments keep the operating field clear of excess blood.
4.Assistant:The job of the assistant is to anticipate and facilitate. The person assisting the surgeon should have a clear knowledge of the surgery as on many occasions he/she will not be able to see what is going on inside.
Nasal packing:Nasal packing is done with ribbon gauze soaked in 0.05% xylometazoline. While putting nasal pack one should be aware of not pushing it too far superiorly in the roof of the nose with the potential risk of breaching the cribriform plate and CSF leak.
Incision:Though various incisions have been described, a straight incision 3-4 mm from medial canthus and 10-12 mm in length provides adequate exposure and also keeps the angular vein away from the surgical site.
Lacrimal sac dissection:After the incision blunt dissection is carried out to reach up to the periostium. The periostium is then reflected off with the help of Freer’s perisoteal elevator. Some surgeons prefer preserving the medial canthal tendon (MCT). The structure being a landmark for the most inferior projection of the cribriform plate of ethmoid bone, there are chances of it getting damaged with rotational forces of bone punch and CSF leak. However snipping off the MCT provides good exposure of the fundus of the sac, and injury to cribriform plate can be avoided if one is careful enough in removing bone in this area not go too high up. Normally the cribriform plate lies 25 mm from the common internal punctum. Once the sac is exposed it is dissected off the lacrimal sac fossa with blunt dissection and the fossa is exposed.
Creating bony ostium.Once the sac fossa is exposed the bone punching is started after breaking the thin suture line between the lamina papyracea of the ethmoid bone and lacrimal bone. Care should be taken that the roungers punch is inserted between the nasal mucosa and bone, and the nasal mucosa doesn’t get injured or torn. The following are the boundaries of the desired ostium.
1. Anteriorly till the punch can’t be inserted between the nasal mucosa and bone.
2. Posteriorly till posterior lacrimal crest.
3. Superiorly just above MCT (not more than 2 mm).
4. Inferiorly till NLD is deroofed.
Silicone tube intubation.Indications for silicone tube intubations are:
1. The resistance felt during passing the probe through the common canaliculus while raising sac flap.
2. Traumatic NLDO.
3. Revision DCR
Flap creation and anastomosis:For creating sac flap a Bowmann probe is passed through the lower punctum and the sac is tented as posterior as possible to create a big anterior flap. An incision is then given from the fundus of the sac up till the NLD. The anterior flap is raised by converting the incision into an H shape. The posterior flap is cut. Similarly, an anterior nasal mucosal flap is raised and the posterior one is excised. Both the flaps are then anastomosed with the help of absorbable 6-0 vicryl sutures. The flaps can then be sutured to the overlying periostium to keep them in a hinged up position.
Wound closure:After flaps are anastomosed, the wound can be closed by apposing orbicularis with 6-0 vicryl sutures and skin with 6-0 nylon. Alternatively, skin can also be apposed with the help of glue, especially in children.
Post-op care includes:
Keep a watch on nasal bleeding.
Head end elevation.
Avoid blowing nose
Start nasal decongestant.
Systemic antibiotics and analgesics and topical antibiotic steroid eye drops.
The patient is called after 1 week for suture removal and syringing. Patient is then reviewed at 6 weeks, 6 months and 1 year. Any tube removal is done after 3 months.
To enumerate the following are some of the possible complications in any external DCR surgery.
1. Intraoperative, immediate and delayed hemorrhage.
2. Orbital emphysema.
3. Orbital hemorrhage.
4. CSF leakage.
6. Silicone tube related complications (tube migration, slit canaliculus).
7. Obstruction of the nasofrontal duct leading to frontal sinusitis and frontal sinus mucocele.
8. Scar disfigurement.
9. Persistent epiphora.