Diversity in Lacrimal Pathway Morphology Among Patients with Congenital Nasolacrimal Duct Obstruction

Purpose: This prospective observational study aimed to explore the diversity in lacrimal pathway morphology among patients with congenital nasolacrimal duct obstruction (CNLDO) by examining dacryocystography (DCG) images. Patients and Methods: The study included 64 patients who underwent DCG before undergoing general anesthesia probing for unilateral CNLDO. Several parameters were measured from the lateral view of the DCG images: (1) the lacrimal sac (LS) and the nasolacrimal duct (NLD) angle, (2) the angle formed by the superior orbital rim (SOR), LS, and the NLD, (3) LS length, and (4) bony NLD length. Additionally, frontal views of the DCG images were utilized to measure (5) LS–NLD angle and (6) LS angle concerning the midline. Results: The average age of the patients was 34.3 months. The mean ± standard deviation of the measurements of the above parameters was (1) − 1.2° ± 16.5° (range: − 44.6° ± 46.6°), (2) − 5.0° ± 10.3° (range: − 24.0° ± 19.0°), (3) 10.2 ± 2.4 mm (range: 6.5– 16.0 mm), (4) 8.0 ± 2.5 mm (range: 3.1– 14.8 mm), (5) 15.6° ± 11.2° (range: − 16.8° ± 41.0°), and (6) 15.1 ± 5.2° (range: 3.3°– 29.8°). All parameters, except for parameter (3), conformed to a normal distribution. Conclusion: This study provides valuable anthropometric data derived from DCG images, highlighting the substantial variability in lacrimal pathway morphology among patients with CNLDO. Furthermore, anatomical constraints made probing with a straight metal bougie anatomically infeasible in 25.0% of the patients included in this study. Plain Language Summary: Understanding the morphology of the lacrimal pathway is crucial for the successful probing treatments in patients with congenital nasolacrimal duct obstruction (CNLDO). This study represents an initial effort to quantify anthropometric parameters of the lacrimal drainage system through dacryocystography images, specifically aiming to highlight the limitations of blind probing procedure. The results underscore significant variations in the morphology of the lacrimal drainage system among patients, which could impact diagnostic approaches and treatment strategies. Additionally, the findings suggest that patients with CNLDO who do not respond to blind probing may have underlying anatomical complexities. Therefore, rather than relying on repeated blind probing, employing dacryoendoscopy-guided probing under direct visualization could offer a more effective therapeutic alternative for complicated cases of CNLDO. Keywords: anatomy, congenital nasolacrimal duct obstruction, dacryocystography, dacryoendoscopy, epiphora, lacrimal lavage, probing, radiology