Dacryocystorhinostomy: Indications, Steps and Complications

External dacryocystorhinostomy surgery is a meticulous procedure requiring a thorough understanding of anatomy and careful consideration of potential complications. We discuss all the steps of the external DCR procedure beginning from indications to the closure of the surgery. By following the outlined steps, surgeons can address lacrimal system disorders and achieve successful outcomes.

Table of Contents

So let us get started with steps of the External DCR surgery. We have discussed about the nerve blocks that can be employed before DCR surgery in the post on important nerve blocks of lacrimal sac.

Indications Of DCR Surgery

Persistent congenital lacrimal duct obstructions unresponsive to previous therapies.
Congenital lacrimal duct obstructions associated with mucocele, dacryocystitis, and not responsive to other treatments.
Primary acquired nasolacrimal duct obstructions (PANDO)
Secondary acquired nasolacrimal duct obstructions (SALDO)

Contraindications Of DCR Surgery

Patients on Anticoagulant Medications: Especially if unable to stop them preoperatively.
Active Dacryocystitis: Delay surgery until the infection is controlled.
Tumors of the Lacrimal Sac: Consider alternative procedures such as dacryocystectomy (DCT).

Preoperative Evaluation

Before embarking on a DCR surgery, essential pre-operative tests include hemoglobin levels, bleeding and clotting time assessments, blood pressure measurements, random blood sugar tests, and additional general anesthesia investigations when required.

Nasal Packing

DCR involves intricate work with delicate nasal mucosa, making nasal packing a vital aspect. Nasal mucosa is initially sprayed with 10% Lignocaine, followed by packing with a solution containing 4% Lignocaine or 0.5% Xylometazoline. .

WHY DIRECTION OF NASAL PACKING IS IMPORTANT:

When packing, directing it posteriorly gets lodged in the inferior meatus, while a superior approach lodges it into the middle meatus. The direction of nasal packing is crucial. It should be directed initially superiorly, followed by posteriorly and then inferiorly to ensure proper lodging in the middle meatus.

STEP 1 : External Skin Incision

Location and Type: The incision, whether straight or curved (10-12 mm), is positioned 3 to 4 mm away from the medial canthus. Caution is exercised not to exceed 2 mm above the medial canthus to prevent undesired consequences.

CLINICAL NUGGET

Complications that may arise at this step :

The angular vein, located 8 mm medial to the medial canthus, should not be violated to prevent excessive bleeding. Therefore , the incision is never made more medial than 3mm from the medial Canthus.
Complications such as scarring or webbing can arise if the incision extends beyond 2mm from the medial canthus and too much into upper eyelid .

STEP 2: Blunt Dissection Of Orbicularis Muscle

Separation of Fibers: Employ blunt dissection to separate orbicularis fibers without cutting to prevent damage to the lacrimal pump mechanism.If the lacrimal pump is damage a DCR will ultimately fail as the tears will not reach the puncta or sac.

STEP 3 : Identification of Medial Palpebral Ligament and Anterior Lacrimal Crest

Medial Palpebral Ligament: Identify and disinsert the medial palpebral ligament, ensuring not to dissect it. This ligament has anterior, posterior, and superior limbs, with the superior limb crucial for maintaining the contour of the medial canthus. Only the anterior limb is disinserted , therefore the contour of the medial canthus is unaffected post surgery .
Anterior Lacrimal Crest: Expose the anterior lacrimal crest by reflecting the medial palpebral ligament laterally. At this point one can identify the periosteum covering the bone.
Periosteum Exposure: Using a Freer periosteal elevator, the periosteum is separated from the bone and reflected laterally. Subperiosteal dissection is crucial to avoid bleeding from the perilacrimal sac plexus

STEP 4 : Exposure of Lacrimal Fossa

Relevant Anatomy of Lacrimal Fossa: Understand the lacrimal fossa, comprising the thicker frontal process of the maxillary bone and the thinner lacrimal bone.
Maxillary Dominated Fossa: In some cases, the maxillary bone contributes more than the lacrimal bone, creating a maxillary-dominated fossa. This can complicate osteum creation due to the thicker maxillary bone.

STEP 5 : Creation Of Bony Ostium

Sutural Line Fracture: A sutural line between the frontal process of the maxillary bone and the lacrimal bone is carefully fractured, creating an opening into the nasal cavity.
Osteotomy Tool: A Karrison bone nibbling rongeur, with a J-shaped end, is used to nibble the bone, gradually enlarging the osteum.
Limits and Size of Osteum: The osteum must be of adequate size (10-12 mm). However, some scholars understand and advocate that 8 by 8 millimeters is also acceptable. The limits of the ostium are as follows:-

BOUNDARIES OF AN IDEAL OSTIUM IN DACRYOCYSTORHINOSTOMY.

ANTERIORLY till the punch cannot be inserted between the bone and the nasal mucosa.
POSTERIORLY till removal of aerated ethmoid.
SUPERIORLY till 2 mm above the medial canthus.
INFERIORLY till the nasolacrimal canal is partly deroofed.

COMPLICATIONS ASSOCIATED WITH OSTIUM CREATION :-

CSF Rhinorrhea: Care should be taken not to create a superior or high ostium, as it can lead to damage to the cribriform plate and cerebrospinal fluid (CSF) rhinorrhea. One should not extend beyond the fronto-ethmoido suture while creating the ostium. Also Torsional motions during bone nibbling may inadvertently extend fractures, causing CSF leakage. Post DCR if a patient presents with chronic headaches with rhinorrhea, damage to cribriform plate should be suspected.
Sump Syndrome: An insufficient size osteotomy inferiorly may lead to tears accumulating in the lower part of the lacrimal sac, causing sump syndrome. A revision DCR or laser can be used to extend the osteotomy inferiorly to treat sump syndrome.

STEP 6 : Identification Of Lacrimal Sac And Flaps Creation

Identification of Lacrimal Sac: Using a Bowman’s probe through an upper punctum, the lacrimal sac is identified without damaging the common internal punctum.Damage to Common internal punctum can cause secondary closure of the common canaliculus and failed DCR
Tenting of the Sac:The sac is tented at the junction of its posterior and medial borders, assisting in its identification.

I-Shaped Incisions:

Separate vertical incisions are meticulously made in both the lacrimal sac and the adjacent nasal mucosa. These initial incisions create two ‘I’ shapes, one in the lacrimal sac and another in the nasal mucosa. Each ‘I’ shape extends from the fundus of the lacrimal sac down to the nasolacrimal duct, forming central vertical lines in both structures.

Horizontal Extension of incision/ Converting I shaped incision to H shaped Incision

Following the vertical incision, two horizontal incisions are carefully introduced at either end of the vertical line, converting the ‘I’ shape into an ‘H’ shape. These horizontal incisions extend outward from the central vertical line.

This results in the formation of two distinct sets of flaps – anterior and posterior flaps in both the lacrimal sac and the nasal mucosa
Posterior flaps are excised.
Anterior flaps are sutured with 6-0 Vicryl, connecting the lacrimal sac to the nasal cavity
CREATION OF FUNCTIONAL CONNECTION :The suturing process creates a connection between the anterior flaps of the lacrimal sac and nasal mucosa, establishing a functional ostium behind them, that allows for the proper drainage of tears.

CLINICAL NUGGET

The leading reason for DCR failure is often due to the soft tissue blocking the ostium. Also, fibrous growth can contribute to this issue. However, this can be successfully prevented by utilizing antifibrotic agents such as mitomycin c.(0.2mg/ml-0.5mg/ml)

STEP 7 : Wound Closure

Orbicularis and Skin Closure: Appose the orbicularis with 6-0 Vicryl and close the skin with 6-0 nylon or Silk. In pediatric cases, glue can be used.
Stent Considerations: Silicone stents may be inserted through the canalicular system. Stents are generally removed after 8 to 12 weeks, with some advocating for removal at the 4-week mark to prevent biofilm formation.

DCR surgery is a meticulous procedure requiring a thorough understanding of anatomy and careful consideration of potential complications. By following the outlined steps, surgeons can address lacrimal system disorders and achieve successful outcomes.If you are an audiovisual learner and wish to learn about DCR that way,you can watch our video on DCR steps on youtube.