Normative dimensions and symmetry of the lacrimal drainage system on dacryocystography: statistical analysis of morphometric characteristics
Abstract
Background: Asymmetric lacrimal flow occurs in females more than males. We hypothesised that the normal lacrimal drainage system (LDS) may show subtle left-rightasymmetry in morphometry when imaged on dacryocystography (DCG).
Materials and methods: We retrospectively reviewed 60 normal bilateral LDSs.Images were analysed for 7 parameters: (1) combined length of either the superioror inferior canaliculus plus common canaliculus, (2) angle of insertion of common canaliculus into lacrimal sac (LS), (3, 4) length and width of the LS, (5) length of thenasolacrimal duct (NLD), and (6, 7) width of proximal and distal NLD. We testedthe effect of independent variables (age, gender, and side) on each dependentvariable (length, width, or angle) using regression analysis. We used a Studentt-test for independent samples to statistically compare bilateral LDSs.
Results: Patient median age was 62 years, and male:female ratio was 27:73. Mean dimensions and angles for all LDSs were: (1) 14.5 mm, (2) 57°,(3) 11.6 mm, (4) 2.1 mm, (5) 20.7 mm, (6) 1.4 mm, and (7) 1.8 mm. No independent variable affected variation in length, width, or angle. No significant difference emerged between dimensions of right and left LDSs in both sexes.Conclusions: A degree of affective lateralisation in the brain is known to result inlacrimal flow asymmetry after mood manipulation. We show that this is not reflected in LDS anatomy. Moreover, our detailed morphometric data can aid in therapeuticplanning of LDS luminal procedures, especially when DCG images of one LDS are used as a road map for contralateral interventions.
