Endoscopic Dacryocystorhinostomy (En-DCR): Complete Guide

Part 1: Anatomy of the Lacrimal Drainage System

Puncta

• Located at the posterior edge of the lid margin, at the junction of the lash-bearing lateral 5/6 (pars ciliaris) and the medial non-ciliated 1/6 (pars lacrimalis).
• Normally face slightly posteriorly and can be seen by everting the medial aspect of the lids.

Canaliculi

• Each canaliculus first runs vertically for ~2 mm from the lid margin - this vertical segment is called the ampulla.
• It then turns medially and runs horizontally for ~8 mm to reach the lacrimal sac.
• The horizontal canaliculus is surrounded by the Horner muscle (palpebral part of orbicularis oculi).
• The superior and inferior canaliculi unite in >90% of cases to form the common canaliculus, which opens into the lateral wall of the lacrimal sac.
• A mucosal fold called the valve of Rosenmüller guards the junction of the common canaliculus and the sac, preventing reflux.

Lacrimal Sac

• 10-12 mm long, lies in the lacrimal fossa between the anterior and posterior lacrimal crests.
• Bounded laterally by the frontal process of the maxilla and medially by the lacrimal bone, which separates it from the middle meatus of the nasal cavity.
• The upper 1/3 of the sac lies just superior to the anterior insertion of the middle turbinate.
• The remaining inferior 2/3 is oriented vertically, just under the anterior maxillary line (lacrimomaxillary suture).
• The axilla of the middle turbinate is the most reliable endoscopic landmark to locate the lacrimal sac.
• The common canaliculus (common internal punctum) opens into the sac approximately 3 mm above the axilla of the middle turbinate.

Nasolacrimal Duct

• 12-18 mm long - the inferior continuation of the lacrimal sac.
• Descends slightly laterally and posteriorly to open into the inferior nasal meatus, lateral to and below the inferior turbinate.
• Opening is partially covered by a mucosal fold: the valve of Hasner.

Part 2: Physiology of Tear Drainage (Why the Pump Matters)

1. Tears flow along the upper and lower marginal strips, pooling in the lacus lacrimalis medial to the lower puncta.
2. With each blink: orbicularis oculi (pretarsal part) compresses the ampullae, shortens the horizontal canaliculi, closes the puncta medially, and creates positive pressure forcing tears down the nasolacrimal duct - mediated by helically arranged connective tissue fibers around the sac.
3. When the eyes open: canaliculi and sac expand, creating negative pressure that draws tears from canaliculi into the sac.

Part 3: Sac Syringing (Lacrimal Irrigation) - Step by Step

Equipment

• Lacrimal dilator (Nettleship)
• 25-gauge blunt lacrimal cannula on a 2 mL syringe filled with saline
• Optional: fluorescein dye

Technique

1. Dilate the punctum with a Nettleship dilator using a rotating motion, first vertically then horizontally.
2. Insert the 25-gauge blunt cannula into the inferior (or superior) punctum - initially vertical for 2 mm, then horizontal for 8 mm following the canalicular anatomy.
3. Gently irrigate with saline.

Interpreting Results

Jones Tests

• Jones I test: Fluorescein drops in conjunctival fornix. Normal = complete disappearance within 5 min with dye recoverable from nose/throat on cotton swab (positive Jones I). Abnormal = obstruction present.
• Jones II test: After a negative Jones I, the conjunctival sac is irrigated with saline after placing fluorescein. Recovery of fluorescein-stained saline from the nose = obstruction is distal (duct level). Recovery of unstained saline = functional obstruction. No recovery = complete obstruction.

Part 4: What Is Endoscopic DCR?

Epiphora vs Watery Eye

• Epiphora: tears overflow the lid margin and run down the face - caused by obstruction, treated surgically.
• Watery eye: abnormally thick tear film alters vision but does not drain down the skin - caused by tear film composition problems or reflex tearing, treated medically.

Types of Obstruction

Advantages of Endoscopic over External DCR

• No external facial scar
• Similar success rates to external DCR
• Better visualization of the agger nasi region
• Ideal for revision cases
• Preserves the medial canthal tendon and lacrimal pump mechanism

Part 5: Pre-operative Workup and Diagnostics

Clinical Examination

1. Exclude lid laxity, malposition, punctal anomalies, blepharitis.
2. Palpate over the lacrimal sac - reflux of mucopurulence = dacryocystitis (obstruction amenable to DCR).
3. Dye disappearance test (Jones I) as described above.
4. Probing with Bowman probe to differentiate hard stop (sac entry - patent canaliculi) from soft stop (canalicular stenosis).
5. Syringing (Jones II) to confirm site of obstruction.

Imaging

• Dacryocystogram (DCG): Contrast injected into lacrimal system. Anatomic obstruction shows dye failing to pass beyond the sac-duct junction. Functional obstruction shows dye penetrating the nasal cavity but with delayed scintigraphy.
• Lacrimal scintigraphy: More physiologic - uses a drop of radiolabeled isotope in the conjunctival sac to measure transit time.
• CT-DCG: Best for pre-operative planning in endoscopic DCR - localizes the fundus of the sac relative to the middle turbinate axilla.

Part 6: Surgical Steps of Endoscopic DCR (Powered Technique)

Setup and Anesthesia

• General or local anesthesia with sedation.
• Patient positioned with head raised ~30 degrees to reduce venous congestion.
• 1% lidocaine with 1:100,000 epinephrine injected into the anterior lateral nasal wall for vasoconstriction and hydrodissection.
• Neuropatties containing 1:1000 epinephrine packed into the nasal cavity.
• 30-degree nasal endoscope used throughout, aimed in a superolateral direction.

Step 1: Septoplasty (if needed - ~50% of cases)

• A high endoscopic septoplasty is performed if the axilla of the middle turbinate cannot be completely visualized due to a deviated nasal septum.
• This creates adequate working space in the anterior-superior nasal cavity.

Step 2: Mucosal Flap Elevation

• A posteriorly pedicled mucoperiosteal flap is outlined with a No. 15 blade:
  • Vertical incision from the axilla of the middle turbinate downward
  • Horizontal incision along the inferior border
  • The flap dimensions are approximately 10 mm wide x 15 mm tall
• A sharp-suction Freer elevator achieves the elevation.
• The flap must be aggressively elevated off the entire lacrimal bone so that it remains attached only inferiorly at the uncinate process and superiorly at the axilla.
• Hemostasis is regained with topical vasoconstrictors before proceeding.

Step 3: Bone Removal

• A 4-mm Hajek-Koeffler punch (forward-biting) removes the frontal process of the maxilla covering the anterior lacrimal sac.
• Critical technique: Release the punch after each bite - failure to do so may inadvertently tear the sac wall.
• The thin lacrimal bone over the posterior sac is easily flaked off with a round knife.
• A DCR drill (diamond bur) then "saucerizes" the remaining bone to the edges of the original mucosal incisions.
• Drilling is complete when a hemisphere of the lacrimal sac sits "proud" on top of the saucerized bone - this allows flaps to lie open during healing rather than curl inward.
• The agger nasi cell is opened in almost all DCRs (incorporated into the marsupialized sac in ~55%).

Step 4: Cannulation (Probe Insertion)

• Superior and inferior puncta are dilated with a lacrimal dilator.
• A Bowman probe (00 size) is passed through the inferior canaliculus:
  • Initially directed horizontally and slightly posteriorly
  • As the sac is approached, tip is directed superiorly through the common canaliculus into the lacrimal sac
• Confirmation is essential: The tip of the probe must be clearly visible tenting the medial sac wall before cutting. If the whole sac moves with the probe but the tip is not visible, the probe is still in the common canaliculus - cutting here will damage the common internal punctum and cause surgical failure.
• An optical fiber light guide can alternatively be used for transillumination to identify the sac through the nasal wall.

Step 5: Marsupialization of the Lacrimal Sac

• Once the probe tip is clearly tenting the sac, a spear knife (sickle knife) opens the sac vertically from top to bottom.
• A ball probe is then passed through the medial sac wall incision to check adequacy of bone removal - any remaining bone is removed at this point.
• The common internal punctum (opening of common canaliculus) should now be visible approximately 3 mm above where the axilla was located.
• Anterior and posterior mucosal flaps of the sac are trimmed to create a wide opening (anterior flap retained, posterior flap trimmed or folded back against the septum/middle turbinate).
• The mucosal flap elevated from the lateral nasal wall is folded back over the middle turbinate to oppose the posterior sac flap and promote mucosalization rather than granulation.

Step 6: Silicone Stent Placement (Optional)

• Bicanalicular silicone intubation (Crawford tubes) may be placed through both canaliculi, through the new ostium, and out via the nasal cavity where they are clipped or tied.
• Stents maintain the ostium during early healing and prevent scarring.
• Note: Current evidence shows silicone tubing is not always necessary after primary En-DCR when the ostium is adequately large.
• Tubes are left in place for 1-6 months and removed via the nose (not pulled from the eye) to prevent aspiration.

Step 7: Post-operative Care

• Nasal saline irrigations begin the following day.
• Topical nasal steroid sprays reduce mucosal inflammation.
• Antibiotic-steroid eye drops for 4-6 weeks.
• Endoscopic review at 4-6 weeks to assess the ostium and remove any granulations.

Part 7: Complications of Endoscopic DCR

Intraoperative Complications

Post-operative Complications

Part 8: Causes of Surgical Failure and How to Prevent Them

1. Inadequate bone removal (most common cause overall): Any remaining bone creates a fluid meniscus. Prevention: Complete saucerization until the sac sits proud; use a ball probe to palpate the opened sac for hidden bony ledges.
2. Sac not fully opened: Not all of the sac mucosa is marsupialized. Prevention: Identify and center the common internal punctum in the ostium.
3. Granuloma at the ostium: Prevention: Mucosa-to-mucosa apposition of sac flap to nasal mucosal flap; topical steroids post-operatively.
4. Cheese-wiring by stent: Prevention: Loop technique when securing tube in the nose.
5. Proximal obstruction: DCR cannot succeed if the obstruction is at the level of the canaliculi (common canalicular stenosis) - must be diagnosed pre-operatively.

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