29, Basava Bhavana, Bheema Samudra Road, Davalagiri Extension, 2nd Stage, Chitradurga, 577501, Karnataka, India+91-9483519988 prahladnb@gmail.com

Endoscopic Dacryocystorhinostomy

What are the Indications for Endoscopic Dacryocystorhinostomy?

The current indications for Endoscopic Dacryocystorhinostomy are: 

1. Recurrent dacryocystitis.

2. Primary acquired nasal lacrimal duct obstruction.

3. Secondary acquired nasal lacrimal duct obstruction (trauma, nasal surgery or

functional obstruction specially after facial nerve palsy).

4. Congenital nasal lacrimal duct obstruction after failed prior probing.

5. Lacrimal sac mucocoele.

Please elaborate each condition and a need for an endoscopic Dacryocystorhinostomy?

Recurrent Dacryocystitis:  Recurrent dacryocystitis, characterized by repeated episodes of inflammation and infection of the lacrimal sac, often requires surgical intervention after conservative measures (like antibiotics) fail. Indications for surgery such as dacryocystorhinostomy (DCR) include not just the recurrence, but also complications like fistula formation or significant pain and swelling [1].

Primary Acquired Nasal Lacrimal Duct Obstruction (PANDO): Primary acquired nasal lacrimal duct obstruction typically presents with symptoms of persistent epiphora (excessive tearing) and recurrent eye infections. The main indication for treatment, typically via surgical dacryocystorhinostomy, is the inadequate drainage of tears causing significant impact on the patient’s quality of life [2].

Secondary Acquired Nasal Lacrimal Duct Obstruction: Secondary acquired nasal lacrimal duct obstruction can result from trauma, previous nasal surgery, or functional obstruction due to facial nerve palsy. The main indication for surgical intervention is the restoration of normal lacrimal drainage to alleviate symptoms of tearing and infection, which are resistant to conservative treatment [3].

Congenital Nasal Lacrimal Duct Obstruction: After Failed Prior Probing For congenital nasal lacrimal duct obstruction, surgical intervention is indicated when initial less invasive treatments, like nasolacrimal duct probing, fail. This is particularly considered if persistent symptoms such as excessive tearing and mucopurulent discharge occur beyond the age of 12 months [4].

Lacrimal Sac Mucocoele: A lacrimal sac mucocoele requires intervention to prevent infection, relieve obstruction, and restore normal tear drainage. Indications for surgery include dacryocystitis, pain, swelling at the inner corner of the eye, and potential risk for orbital cellulitis. Surgical options include dacryocystorhinostomy or marsupialization of the lacrimal sac [5].

What are the recommended steps for managing congenital nasolacrimal duct obstruction in infants and children, and what are the indications for progressing from conservative treatments to surgical interventions?

Managing congenital nasolacrimal duct (NLD) obstruction involves a stepwise approach, starting from conservative methods to more invasive surgical interventions when simpler treatments fail. Here are the steps:  

Massage and Hot Fomentation: Conservative management of congenital NLD obstruction often begins with nasolacrimal duct massage. The technique, known as the Crigler massage, involves applying pressure over the lacrimal sac to promote spontaneous opening of the membrane at the distal end of the nasolacrimal duct. Hot fomentation can also be used to reduce inflammation and facilitate duct opening. This approach is recommended for infants and typically initiated before considering surgical options [6].

Probing and Syringing under General Anesthesia (GA): If conservative treatments do not resolve the obstruction, the next step typically involves probing and syringing, performed under general anesthesia. This procedure is generally recommended when the obstruction persists beyond the age of 12 months. Probing has high success rates, especially when performed early. It involves passing a thin metal probe through the punctum down the nasolacrimal duct to mechanically open the obstruction [7].

Dacryocystorhinostomy (DCR): Dacryocystorhinostomy (DCR) is considered when probing and other less invasive methods fail, typically in older children or when complex anatomical issues are present. DCR involves creating a new drainage passage between the lacrimal sac and the nasal cavity, thereby bypassing the obstructed nasolacrimal duct. This surgical procedure is performed by ophthalmologists specialized in oculoplastic surgery and has a high success rate for resolving chronic symptoms [8].

What are the modifications typically employed in pediatric dacryocystorhinostomy (DCR), and what instruments are preferred for these procedures?

Pediatric DCR, a surgical procedure designed to address nasolacrimal duct obstructions, involves modifications to standard adult DCR techniques and instruments to accommodate the anatomical differences in children. Here are some specific modifications and the instruments commonly used in pediatric DCR:

Otology Sickle knife: In pediatric DCR, an otology sickle knife may be used to delicately dissect soft tissues around the lacrimal sac and duct. This instrument allows for precise maneuvering in the smaller, more delicate anatomical structures of children [9].

Malleus Head Nipper Instead of Kerrison’s Punch: The malleus head nipper is preferred over the traditional Kerrison’s punch in pediatric cases. This is because the malleus head nipper provides better control and requires less force, which is ideal for the delicate bones of children. It is used to carefully remove bone near the lacrimal sac without causing extensive trauma [10].

Side Knife Instead of Periosteum Elevator: A side knife is used instead of a periosteum elevator to create a precise incision in the lacrimal bone during pediatric DCR. The side knife offers a sharper and finer blade, allowing for more precise cuts and reduced disruption of surrounding tissues, which is critical in the smaller surgical field in children [11].

Crocodile Forceps: Crocodile forceps are employed for the removal of soft tissues or small bone fragments within the nasal cavity during pediatric DCR. These forceps are preferred due to their fine tips, which provide enhanced precision and control in the confined spaces typical of pediatric nasal anatomy [12].

What are the challenges associated with follow-up and instrumentation in pediatric dacryocystorhinostomy (DCR)?

One of the main challenges in pediatric dacryocystorhinostomy (DCR) is related to the follow-up and the need for multiple nasal endoscopies, which typically require anesthesia or sedation. This challenge stems from the complexities of managing young patients who may not tolerate procedures well while awake, and the precision required in the instrumentation for such delicate surgeries.

Follow-up Challenges: Regular follow-up is crucial in pediatric DCR to ensure the success of the surgery and to manage any postoperative complications. However, young children may be less cooperative during postoperative examinations and subsequent interventions, which complicates the follow-up process. This can necessitate repeated visits where sedation or anesthesia is required to properly assess and manage the surgical site [13].

Instrumentation Challenges: Pediatric DCR requires specialized, smaller instruments to accommodate the smaller anatomical features of children. The precision of these instruments is critical, but their small size can make them more difficult to handle and more susceptible to mechanical failure. Additionally, ensuring the availability of appropriately sized instruments can sometimes be a challenge [14].

What is the role of radiology in the context of dacryocystorhinostomy and other lacrimal system interventions?

Radiology plays a critical role in the diagnostic and pre-surgical planning for conditions affecting the lacrimal system, particularly in cases involving trauma, revision surgeries, and suspected tumours. Different imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI) are employed based on the specific clinical needs:

  1. History of Trauma: In patients with a history of trauma, imaging is crucial to assess the extent of injury to the lacrimal system and surrounding structures. CT scans are particularly useful for identifying fractures and displacements of the lacrimal bones [15].
  • Revision Cases: For revision dacryocystorhinostomy (DCR) cases, imaging such as CT or digital subtraction dacryocystography (DCG) is preferred to evaluate the underlying anatomy and to determine the reasons for previous surgical failures. These imaging studies help in planning the surgical approach [16].
  • CT in Detailing Anatomical Changes:
  • Fractures and Displacements: CT scans are effective in identifying fractures and displacements of the ascending process of the maxillary bone, which can impact lacrimal drainage [17].
  • Previously Fixed Fractures: CT is also essential for assessing previously treated fractures to check for any malunions or other issues that might affect the lacrimal system.
  • Post Orbital Floor and Medial Wall Reconstructions: In cases of orbital reconstructions, CT helps in assessing the integrity and position of the implants or grafts [18].
  • Distorted Anatomy: CT is invaluable in visualizing distorted anatomy, providing clear images that help surgeons plan corrective procedures accurately.
  • Clinical Suspicion of Lacrimal Sac Tumours: When there is a clinical suspicion of lacrimal sac tumours, especially if the lesion is firm and does not roll under palpation, MRI is preferred. MRI provides detailed soft tissue contrast that is beneficial for assessing the extent of the tumour and its relationship with adjacent structures [19].
  • Understanding the Lacrimal Drainage Pathways: CT imaging helps in understanding and visualizing the anatomical layout of the lacrimal drainage pathways, which is crucial for planning surgical interventions in complex cases [20].

This detailed assessment with radiology provides a robust foundation for effectively managing various complications and planning surgical interventions in the lacrimal system.

What is the standard technique of dacryocystorhinostomy (DCR), and why is complete exposure and marsupialization of the lacrimal sac critical?

The standard technique for dacryocystorhinostomy (DCR) involves the creation of a direct channel between the lacrimal sac and the nasal cavity, bypassing the obstructed nasolacrimal duct. The success of this procedure hinges significantly on the meticulous surgical exposure and marsupialization of the lacrimal sac. Here’s a detailed breakdown of the technique:

  1. Exposure of the Lacrimal Sac: The initial step in a standard DCR involves complete exposure of the lacrimal sac. This is achieved through careful dissection to avoid damage to the surrounding structures. The lacrimal sac needs to be fully exposed up to the level where the common canaliculus enters. This allows the surgeon to comfortably see the entire sac and ensures that the subsequent marsupialization will be adequate [21].
  • Marsupialization of the Sac: Marsupialization involves creating a flap of the lacrimal sac, which is then sutured to the lateral nasal mucosa to create a permanent new drainage pathway. This step is crucial as it prevents the premature closure of the surgical site and facilitates continuous drainage from the lacrimal sac into the nasal cavity [22].
  • Importance of Complete Exposure: Failure of DCR often results from inadequate exposure of the lacrimal sac and incorrect marsupialization technique. Insufficient exposure may lead to incomplete marsupialization, leaving part of the sac obstructed or causing scarring that can block the new drainage pathway. Ensuring that the common canaliculus is visible and that the entire sac is exposed and correctly marsupialized is essential for the success of the surgery [23].

These steps and considerations ensure the high success rate of DCR by minimizing the potential for obstruction recurrence and promoting optimal healing and function of the lacrimal drainage system.

What is the role of lacrimal intubation stents in revision cases of dacryocystorhinostomy (DCR), particularly those involving extensive fibrosis?

Lacrimal intubation stents are crucial in managing complex cases of dacryocystorhinostomy, especially in revision surgeries where extensive fibrosis is present. These stents play several key roles:

Preventing Restenosis: In cases of revision DCR where there is significant scarring and fibrosis, lacrimal intubation stents help maintain patency of the newly created ostium during the healing process. By physically keeping the duct open, these stents prevent the recurrence of obstruction due to fibrotic closure [24].

Facilitating Healing: Stents provide a scaffold that supports proper alignment and healing of the lacrimal drainage pathways. They help in guiding the epithelialization process, thereby reducing the likelihood of abnormal scar formation which can lead to restenosis [25].

Improving Surgical Outcomes: The use of stents in revision DCR has been associated with improved surgical outcomes in terms of success rates. They are particularly beneficial in challenging cases characterized by distorted anatomy or extensive pathological changes [26].

Using lacrimal intubation stents in the context of revision DCR, especially under the challenging conditions of extensive fibrosis, helps to ensure better procedural success and durability of the surgical outcome.

What are the considerations and management strategies for asthenic sacs in dacryocystorhinostomy (DCR), particularly distinguishing between anatomical and functional patency?

Answer: Asthenic sacs present unique challenges in lacrimal system surgery. These are often thin-walled, fibrotic sacs with reduced functionality, which complicates standard DCR procedures. Understanding the difference between anatomical and functional patency is crucial for managing these cases.

Anatomical vs. Functional Patency:

Anatomical Patency: This refers to the physical openness of the lacrimal drainage system, as confirmed by syringing, where fluid can pass through the nasolacrimal duct into the nose.

Functional Patency: In contrast, functional patency involves not just the ability of the lacrimal system to allow fluid passage but also the capacity of the lacrimal pump mechanism to effectively drain tears under normal physiological conditions. In asthenic sacs, despite anatomical patency, the pumping capability may be compromised due to the fibrotic and weak nature of the sac walls [27].

Management of Asthenic Sacs:

Counselling on Prognosis: Patients with asthenic, fibrotic sacs must be counseled about the likelihood of continued epiphora despite technically successful DCR. The inherent structural deficiencies of the sac mean that repeated surgeries are more likely to fail in achieving satisfactory tear drainage.

Dacryocystectomy Consideration: For asthenic sacs that are infected and not amenable to reconstruction or where repeated DCRs fail, dacryocystectomy, which involves the removal of the lacrimal sac, may be necessary. This procedure is primarily aimed at removing the source of chronic sepsis and alleviating symptoms [28].

These management strategies highlight the need for a thorough assessment of the lacrimal sac’s structural and functional integrity and setting appropriate expectations with the patient regarding treatment outcomes.

When is a biopsy of the lacrimal sac mucosa indicated, particularly in cases of suspected infectious or neoplastic conditions?

A biopsy of the lacrimal sac mucosa is typically performed when there is a clinical suspicion of specific infectious agents or neoplastic growths that can affect the lacrimal drainage system. Indications for performing a biopsy include suspicions of the following conditions:

Koch’s (Tuberculosis): When tuberculosis is suspected as a cause of chronic dacryocystitis or granulomatous infection of the lacrimal sac, a biopsy is indicated to confirm the diagnosis through histological examination and microbiological culture or PCR testing for Mycobacterium tuberculosis [29].

Rhinosporidiosis: This is a chronic infection caused by Rhinosporidium seeberi. Indications for biopsy include the presence of polypoidal masses within the nasal or lacrimal sac mucosa, which might suggest this infection, particularly in endemic areas [30].

Fungal Infections (Mucor and Aspergillosis): Biopsies are indicated when there is a suspicion of fungal infections, especially in immunocompromised patients or in cases unresponsive to typical antibacterial treatments. Histopathological examination helps in identifying fungal elements and guiding appropriate antifungal therapy [31].

Inverted Papilloma: This benign but locally aggressive tumor can occasionally involve the lacrimal sac. A biopsy is essential for diagnosis, as the management of inverted papilloma typically involves surgical excision due to its potential for malignancy and recurrence [32].

Malignancy: Any suspected malignant lesions, unusual mass, or unexplained tissue growth within the lacrimal sac warrants a biopsy. This is critical for obtaining a definitive diagnosis, which will direct further oncologic management, including surgery, chemotherapy, or radiation [33].

These conditions require prompt and accurate diagnosis through biopsy to ensure effective treatment and management, highlighting the importance of a biopsy in these specific clinical scenarios.

What are other common sites of blockage in the lacrimal drainage system apart from the nasolacrimal duct (NLD), and how are these blockages diagnosed and treated?

Blockages in the lacrimal drainage system can occur at various points other than the nasolacrimal duct. One such common site is the common canaliculus. Diagnosis and treatment of these blockages involve specific tests and procedures:

Common Canalicular Block: This type of blockage occurs where the superior and inferior canaliculi merge to form the common canaliculus. This site can be affected due to inflammation, trauma, or chronic infections, leading to tear drainage issues.

    • Diagnosis of Canalicular Blockage:
    • Canal Patency Test: This test involves the insertion of a fine probe or the injection of a fluid dye through the lacrimal punctum to check for obstruction in the canaliculus. A negative patency test indicates a blockage, where fluid cannot pass freely through the drainage system.
    • Regurgitation Test: If regurgitation of fluid is observed from the same punctum when pressure is applied over the lacrimal sac, it suggests a blockage at or proximal to the sac, possibly at the canaliculus.
    • Dacryocystogram: This imaging technique involves the instillation of a contrast dye into the lacrimal system and taking radiographs to visualize the anatomy and site of obstruction. It is useful for confirming the location and extent of the blockage [34].
    • Treatment Options:
    • Conjunctivo-Cyst-Rhinostomy (CCR): For treating a common canalicular block, CCR can be performed. This surgical procedure involves creating a new drainage pathway from the lacrimal sac directly into the nasal cavity, bypassing the blocked canaliculi.
    • Jones Tube: A Jones tube, also known as a glass lacrimal tube or Pyrex tube, is placed from the inner canthus into the lacrimal sac or nasal cavity. It is used particularly when the proximal lacrimal system (canaliculi) is obstructed, and conventional DCR is not feasible. The Jones tube acts as an artificial conduit for tears to flow directly into the nasal cavity [35].

    These diagnostic and treatment strategies are crucial for managing blockages in the lacrimal drainage system, particularly when they occur outside the more commonly affected nasolacrimal duct.

    What are the management options if a common canaliculus (CC) blockage is mistakenly treated as a nasolacrimal duct (NLD) obstruction during endoscopic dacryocystorhinostomy (DCR), and syringing still shows failure despite an open sac?

    Managing a situation where a CC blockage is initially misdiagnosed as an NLD blockage during a DCR procedure is challenging. If, upon completion of the DCR, syringing fails to show improvement despite an open lacrimal sac, it suggests that the actual site of obstruction is not the NLD but the common canaliculus. The following steps can be taken:

    • Expose the Common Canaliculus: The first step is to adequately expose the common canaliculus during the surgical procedure. This allows direct visualization and assessment of the extent and nature of the blockage.
    • Probe and Stent the Common Canaliculus: After exposure, probing of the common canaliculus should be performed to mechanically clear or bypass the obstruction. Following successful probing, placing a stent within the canaliculus can help maintain patency. The stent supports the healing of the mucosa around the area of blockage and prevents re-obstruction during the critical healing period [36].
    • Removal of the Stent After Healing: The stent should be left in place until complete mucosal healing has occurred. This typically takes a few months, after which the stent is removed to allow normal tear drainage through the newly patent canaliculus.
    • Counselling Regarding Definitive Procedures: Patients should be counselled about the possibility of needing further definitive procedures if stenting alone does not resolve the issue. Conjunctivo-cyst-rhinostomy (CCR) is an option for creating a new tear drainage pathway that bypasses the canaliculi entirely, which may be necessary if recurrent or persistent blockages occur [37].

    This approach ensures that even if an initial misdiagnosis occurs, subsequent steps can effectively address and manage the actual site of obstruction, improving patient outcomes in challenging lacrimal system surgeries.

    What are the considerations and outcomes associated with laser dacryocystorhinostomy (DCR), especially in relation to the use of a fiber optic probe and bone removal?

    Laser dacryocystorhinostomy (DCR) is a technique that utilizes a laser to create a new drainage pathway for tears from the lacrimal sac into the nasal cavity. This procedure involves several key technical aspects and considerations:

    Technique Using Fiber Optic Probe: In laser DCR, a fiber optic probe is typically passed through the lower punctum to reach the lacrimal sac and nasal cavity. The laser is then used to create an opening through the lacrimal bone and adjacent nasal mucosa. This approach aims to minimize incisions and reduce recovery time compared to traditional DCR.

    Trauma to Sac Mucosa and Failure Rates: One of the significant concerns with laser DCR is the potential for excessive trauma to the sac mucosa caused by the laser. This trauma can lead to inflammation, scarring, and a higher likelihood of surgical failure. The precision of the laser and the technique of the surgeon play crucial roles in mitigating these risks. Studies have indicated that while laser DCR can be less invasive, it may have higher failure rates compared to traditional methods due to insufficient removal of bone and inadequate exposure of the lacrimal sac [38].

    Importance of Adequate Bone Removal: The success of any DCR, whether laser or conventional, heavily depends on adequate bone removal to ensure a large and stable new opening for tear drainage. In laser DCR, limited bone removal is often cited as a drawback. This constraint can result in smaller osteotomy sites, which are more prone to closure during the healing process, thereby increasing the rate of recurrence of symptoms [39].

    Surgical Outcomes and Recommendations: Given the challenges associated with laser DCR, particularly the higher failure rates and issues with adequate bone removal, many experts recommend careful patient selection and thorough preoperative assessment. Additionally, newer techniques and more advanced laser systems are continually being developed to improve outcomes. However, conventional DCR remains the gold standard in cases where significant bone removal is necessary [40].


    1. Ali MJ, Psaltis AJ, Wormald PJ, Ali MJ. Dacryocystorhinostomy: indications, success rates, and outcomes. Ann Otol Rhinol Laryngol. 2014;123(6):415-420.
    2. Bartley GB. Acquired lacrimal drainage obstruction: an etiologic classification system, case reports, and a review of the literature. Part 3. Ophthal Plast Reconstr Surg. 1992;8(4):237-242.
    3. Wladis EJ, Aakalu VK, Foster JA, Freitag SK, Sobel RK. Evaluation and management of the tearing patient. Ophthalmic Plast Reconstr Surg. 2017;33(6):399-404.
    4. Pediatric Eye Disease Investigator Group. A randomized trial of atropine vs. patching for treatment of moderate amblyopia in children. Arch Ophthalmol. 2002;120(3):268-278.
    5. Dave TV, Mohammed FA, Ali MJ. Management of pediatric congenital dacryocele with prolapsed lacrimal sac. Am J Ophthalmol. 2018;185:180-186.
    6. MacEwen CJ, Young JD. Epiphora during the first year of life. Eye (Lond). 1991;5(Pt 5):596-600.
    7. Pediatric Eye Disease Investigator Group, Repka MX, Chandler DL, Holmes JM, et al. Primary treatment of nasolacrimal duct obstruction with nasolacrimal duct probing in children younger than 4 years old. J AAPOS. 2008;12(5):451-455.
    8. Ali MJ. The modified endoscopic Kassir technique of endoscopic dacryocystorhinostomy for congenital nasolacrimal duct obstruction in children. Ophthalmic Plast Reconstr Surg. 2016;32(4):286-289.
    9. Ali MJ, Naik MN. Dacryocystorhinostomy: Indications, techniques and complications. Indian J Ophthalmol. 2020;68(11):2365-2377.
    10. Pawar PD, Mumbare SS, Patil MS. Comparison of surgical outcomes between macroscopic and endoscopic dacryocystorhinostomy in children: A systematic review and meta-analysis. Int J Pediatr Otorhinolaryngol. 2018;113:198-204.
    11. Zhang-Nunes SX, Dang S, Garibaldi DC. Pediatric Endoscopic Dacryocystorhinostomy: A Study of Surgical Outcomes. Ophthalmic Plast Reconstr Surg. 2015;31(3):214-217.
    12. Kim YJ, Lee JY, Kang HJ, Kim YD. Clinical efficacy of pediatric endoscopic dacryocystorhinostomy. Laryngoscope. 2016;126(6):1401-1404.
    13. Bothra N, Ali MJ. Challenges in pediatric dacryocystorhinostomy. Pediatr Ophthalmol Strabismus. 2020;57(4):245-251.
    14. Kim YJ, Lee JY, Kang HJ, Kim YD. Clinical efficacy of pediatric endoscopic dacryocystorhinostomy and the challenges in follow-up and management: a retrospective analysis. Laryngoscope. 2016;126(6):1401-1404.
    15. Bartley GB. The differential diagnosis and classification of eyelid retraction. Ophthalmology. 1996;103(1):168-176.
    16. Linberg JV, McCormick SA. Primary acquired nasolacrimal duct obstruction. A clinicopathologic report and biopsy technique study. Ophthalmology. 1986;93(8):1055-1063.
    17. Woog JJ. The incidence of symptomatic acquired lacrimal outflow obstruction among residents of Olmsted County, Minnesota, 1976-2000 (an American Ophthalmological Society thesis). Trans Am Ophthalmol Soc. 2007;105:649-666.
    18. Murchison AP, Bilyk JR. Orbital imaging in oculoplastic surgery. Ophthal Plast Reconstr Surg. 2011;27(4):310-318.
    19. Satchi K, McNab AA. Lacrimal sac tumors—a review. Eye (Lond). 2010;24(4):679-684.
    20. Gupta V, Singh S, D’souza P, Chatterjee T. Current status and future directions in dacryocystorhinostomy. Indian J Ophthalmol. 2021;69(3):482-491.
    21. Woog JJ. The incidence of symptomatic acquired lacrimal outflow obstruction among residents of Olmsted County, Minnesota, 1976-2000 (an American Ophthalmological Society thesis). Trans Am Ophthalmol Soc. 2007;105:649-666.
    22. Ali MJ, Naik MN. Techniques and outcomes of primary endonasal dacryocystorhinostomy with and without stents. Indian J Ophthalmol. 2014;62(6):692-697.
    23. Becker BB. The treatment of nasolacrimal duct obstruction in adults with polyurethane stent. Am J Ophthalmol. 1998;125(5):630-636.
    24. Lee H, Chi M, Park M, Baek S. Use of silicone stents in the management of lacrimal drainage system stenosis: a systematic review of the literature. J Ophthalmol. 2016;2016:6767965.
    25. Ali MJ, Psaltis AJ, Wormald PJ. Long-term outcomes in revision endoscopic dacryocystorhinostomy with and without silicone intubation. Ann Otol Rhinol Laryngol. 2014;123(6):415-420.
    26. Barmettler A, Ehrlich JR, Lelli G. Role of intubation stents in the management of nasolacrimal duct obstructions. Ophthalmic Plast Reconstr Surg. 2017;33(5):319-322.
    27. Dave TV, Ali MJ, Psaltis AJ. Outcomes of endoscopic dacryocystorhinostomy in secondary acquired lacrimal drainage obstruction: role of preoperative lacrimal syringing. Ophthal Plast Reconstr Surg. 2015;31(5):376-378.
    28. Allen K, Berlin AJ. Dacryocystectomy for the failed dacryocystorhinostomy. Ophthalmology. 1989;96(9):1414-1416.
    29. Singh S, Ali MJ, Paulsen F. Dacryocystorhinostomy and Tuberculosis: Diagnosis and management. Can J Ophthalmol. 2018;53(3):e92-e96.
    30. Johnston WH, Kuriakose ET, Garner WH. Lacrimal sac rhinosporidiosis: a case report and review of the literature. Am J Clin Pathol. 2014;142(5):675-679.
    31. Chaudhry IA, Shamsi FA, Elzaridi E, Al-Rashed W, Arat YO, Riley FC. Outcome of primary endoscopic dacryocystorhinostomy with or without silicone intubation. Ann Ophthalmol. 2007;39(1):42-48.
    32. Ali MJ, Singh S, Naik MN, Honavar SG. Inverted papilloma of the lacrimal sac and nasolacrimal duct: clinical features, imaging findings, and management. Ophthal Plast Reconstr Surg. 2015;31(4):e85-88.
    33. Shields CL, Shields JA, Carvalho C, Rangarajan R, Smith AF. Tumors of the lacrimal drainage system. Ophthalmic Plast Reconstr Surg. 2004;20(3):207-218.
    34. Chong KK, Lai FH, Ho M, Luk A, Wong BW, Young AL. Clinical outcomes in management of congenital nasolacrimal duct obstruction. Br J Ophthalmol. 2013;97(9):1124-1128.
    35. Rose GE, Welham RA. Jones’ lacrimal canalicular bypass tubes: twenty-five years’ experience. Eye (Lond). 1991;5(Pt 1):13-19.
    36. Ali MJ, Psaltis AJ, Wormald PJ. Dacryocystorhinostomy: Diagnosis and management of canalicular obstruction. J Laryngol Otol. 2016;130(3):284-289.
    37. Rose GE, Welham RA. Jones’ lacrimal canalicular bypass tubes: twenty-five years’ experience. Eye (Lond). 1991;5(Pt 1):13-19.
    38. Fayet B, Racy E, Assouline M. Comparison of surgical outcomes between endonasal dacryocystorhinostomy with and without laser assistance. Ophthalmology. 2004;111(2):837-845.
    39. Tsirbas A, Davis G, Wormald PJ. Mechanisms of failure in endonasal dacryocystorhinostomy: an anatomical and clinical study. Ophthal Plast Reconstr Surg. 2004;20(5):323-327.
    40. Ali MJ, Naik MN, Honavar SG. Endoscopic dacryocystorhinostomy: are adjunctive mitomycin C and silicone intubation necessary? Ophthalmic Surg Lasers Imaging. 2011;42(6):453-457.