[Anatomical structure and morphometric parameters of the distal segment of the lacrimal drainage system]. / Anatomicheskoe stroenie i morfometricheskie pokazateli vertikal'nogo otdela slezootvodyashchikh putei.

The article analyzes the literature data concerning the anatomical structure of the tear ducts with a focus on morphometric studies of individual structures. It is noted that, despite the high information content of cadaveric studies, most of the information to date has been obtained with the use of intravital radiation visualization methods. It is shown that the lacrimal drainage system has age, gender, and racial characteristics. Most studies focus on features of the bone nasolacrimal canal, while there is a relative shortage of research devoted to soft-tissue nasolacrimal duct. The analysis showed that most of the studies are devoted to particular morphometric indicators, which makes it difficult to obtain a complete objective picture of the size of the tear duct. Information about its volume can be found only in a couple of studies. The numerical values of the obtained data vary, which can be explained by a different approach to the selection of research subjects, sample sizes, anatomical criteria and the calculation method of morphometric parameters. There are only a few studies on morphometric parameters of the nasolacrimal duct in healthy humans, which is extremely important for determining the pathogenesis of disorders of the patency of the lacrimal drainage system.

Dynamic viscosity of the wall of the lacrimal sac in disorders of the patency of the lacrimal ducts.

PURPOSE: To assess the dynamic viscosity of the lacrimal sac wall in patients with various origins of lacrimal duct obstruction. METHODS: The study was performed in 35 cases: 21 cases with primary nasolacrimal duct obstruction (PANDO) and 14 cases with secondary nasolacrimal duct obstruction after radioiodine therapy (SALDO). The study of biomechanical properties of the lacrimal sac was carried out using a test bench. The principle of the study was to indent the sample at a given speed and record the data obtained from the sensor of the force transmitted to the sample. The area under the curve (AUC) and the peak viscosity were calculated. A qualitative characteristic of the obtained curve was given. RESULTS: Median AUC in patients with PANDO was 17 × 106 [6 × 106; 19 × 106] N/m2 × s, in patients with SALDO 21 × 106 [13 × 106; 25 × 106] N/m2 × s. Intergroup differences were statistically significant (p = 0,048). The median peak viscosity in PANDO patients was 29 × 106 [25 × 106; 35 × 106] N/m2, in patients with SALDO 32 × 106 [21 × 106; 41 × 106] N/m2. The qualitative characteristics of the obtained curves differed. CONCLUSION: Biomechanical properties of the lacrimal sac may vary depending on the cause of obliteration of the lacrimal ducts. The integrated dynamic viscosity is significantly higher in SALDO patients due to exposure to radioiodine compared to that in PANDO patients.

[Biometric characteristics of the lacrimal passages in healthy individuals and in patients with nasolacrimal duct obstruction]. / Biometricheskie kharakteristiki slezootvodyashchikh putei v norme i pri dakriostenoze.

Despite an obvious interest in the processes occurring in the lacrimal passages in their obstruction, there is few articles analyzing their biometric parameters. PURPOSE: The study investigates the biometric characteristics of the lacrimal passages in healthy individuals and in patients with nasolacrimal duct obstruction. MATERIAL AND METHODS: The study included 81 cases of partial nasolacrimal duct obstruction and 38 cases without tear drainage insufficiency. All patients underwent computed tomography with dacryocystography. Analysis of the biometric parameters involved calculation of the length, volume, and average sectional area of the nasolacrimal duct and the nasolacrimal bony canal. The ratio R4/16l was calculated (where R is the radius of the nasolacrimal duct; l is the length of the nasolacrimal duct). The normality of values was assessed using the Shapiro-Wilk test. Intergroup differences were assessed using the Mann-Whitney test and t-statistics for independent samples. Correlation analysis was performed according to the Spearman method. ROC analysis was carried out. Differences were considered significant at p≤0.05. RESULTS: There were significant differences in the volume (p=0.004) and the average sectional area of the nasolacrimal duct (p=0.014), as well as in the length of the nasolacrimal canal (p=0.034). Relationships were established between the age of patients without tear drainage insufficiency and the length of the nasolacrimal canal (p=0.042); the length of the nasolacrimal canal and the volume of the nasolacrimal duct (p=0.034), as well as the volume of the nasolacrimal duct and the nasolacrimal canal in partial nasolacrimal duct obstruction (p=0.017). The AUC of the R4/16l ratio in the ROC analysis was 0.653 (p=0.007). CONCLUSION: In addition to the obvious differences, it was found that the length of the nasolacrimal bony canal significantly differed in the subjects of both study groups. We considered the tear ducts as a hydrodynamic system obeying Poiseuille's law, so we calculated the ratio R4/16l. The value of this ratio varied (p=0.016), and the ROC analysis showed high sensitivity and specificity of the criterion. This makes it possible to use this ratio as a diagnostic criterion for partial nasolacrimal duct obstruction.