Biomechanical properties of lacrimal drainage pathways in dacryostenosis

BACKGROUND: In the literature, there is a deficit of data regarding clinical and morphological correlations in characterizing lacrimal drainage pathways. However, changes in the biomechanical properties of the lacrimal drainage pathways may influence the clinical picture of dacryostenosis, and may also have a predictive value in the context of prognosis of surgical procedures. AIM: The aim of this study is to study of changes in the viscoplastic properties of the lacrimal sac wall in dacryostenosis MATERIALS AND METHODS: The study included 38 patients with dacryostenosis. All patients underwent a biometric examination of lacrimal drainage pathways to determine the average area of their section. All observations were divided into cases with stenotic changes (at an average section area of the lacrimal drainage pathways less than 0.18 mm2 — 26 observations) and with ectatic changes (at an average section area of lacrimal drainage pathways equal to or more than 0.18 mm2 — 12 observations). The biomechanical properties of lacrimal sac wall samples obtained during dacryocystorinostomy were analyzed. The peak value of the viscosity of the lacrimal sac wall and the integral viscosity of the lacrimal sac wall (AUC) were determined. RESULTS: In patients with stenotic changes, a correlation was determined between the duration of lacrimation and the average section area of lacrimal drainage pathways (r = –0.537, p = 0.018), in patients with ectatic changes, a correlation was determined between the average section area of lacrimal drainage pathways and the peak value of the viscosity of the lacrimal sac wall (r = 0.662, p = 0.019). No correlations of biometric parameters with the integral viscosity of the lacrimal sac wall (AUC) were found. CONCLUSIONS: At stenotic changes in lacrimal drainage pathways, the average area of their section depends on the duration of lacrimation; this dependence is absent when a critical level of ectasia is reached. With an increase in the average cut area of lacrimal drainage pathways, the value of the peak viscosity of the lacrimal sac wall increases.