Anatomical Parameters of the Nasolacrimal Duct in Healthy Children Measured with Computed Tomography

OBJECTIVES: This study is an evaluation of anatomical parameters at different levels of the bony nasolacrimal duct (NLD) in healthy children of different age groups using computed tomography (CT) measurements. METHODS: Bony NLD CT images of 289 patients aged 0-15 years who presented at the emergency department with various indications and underwent a brain CT scan were retrospectively evaluated. The anterior-posterior and transverse diameter at the inferior orbital margin, the narrowest diameter of the NLD, NLD length, and the orientation angle in the sagittal plane (the angle between the line connecting the distal and proximal ends of the NLD and a line drawn parallel to the nasal floor) were analyzed by age group. RESULTS: The anterior-posterior and transverse diameters at the level of the inferior orbital margin and the NLD length recorded in sagittal CT images were statistically significantly greater in patients older than 5 years of age (p<0.05). While there was an increase in the narrowest diameter of the NLD beginning at the age of 3 years, it was not statistically significant (p=0.25). The degree of the angle between the central line and the nasal floor did not change significantly between the groups. (p>0.05). CONCLUSION: A greater anterior-posterior diameter, transverse diameter, narrowest diameter of the NLD, and NLD length were observed with increasing age. The NLD anatomical parameters that we have identified in healthy children may serve as an important and useful guide in determining locations of the NLD and selecting surgical instruments of appropriate size and diameter before NLD surgery.