Anatomical Variation of Lacrimal Sac Fossa and Bony Nasolacrimal Duct among Adult Egyptians: Dry Bone and Radiological Study

Background: Successful lacrimal surgery begins with understanding the anatomy of the
lacrimal drainage system. Detailed knowledge of the orientation of the bony lacrimal
passages is a key feature for success of lacrimal probing and intubation. The present study
was assigned to demonstrate the anatomy of the lacrimal drainage system and its variants
among adult Egyptians. Material and methods: The study included 44 dry skulls and 83
multidetector computed tomography (MDCT) images of adults of both sexes. The anterior
and posterior lacrimal crests were examined in dry bones. The length, width of the upper,
middle and lower thirds of lacrimal sac fossa (LSF) were measured using the digital
Vernier caliper. Radiological CT images were examined for anteroposterior and transverse
diameters of the entrance, narrowest point and exit of nasolacrimal duct (NLD). The length
of NLD and the angle between the longitudinal axis of the NLD and floor of the nose were
measured. Results: The LSF was formed by the frontal process of maxilla and lacrimal
bone at different proportions. The width of the middle and lower thirds of LSF were
significantly greater in males than females. Radiological CT images showed that the
anteroposterior and transverse diameters of the entrance of the NLD were significantly
greater in females than males below 40 years. Conclusion: Sex and age of the patient
should be considered while selecting the optimal NLD stent for patient with NLD
obstruction. The precise dimensions of NLD can reduce the risk of injury during the
transnasal operations.
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