View 2024 Abstracts

Purpose

To study the pathogenesis of secondary acquired nasolacrimal duct obstruction (SALDO) due to radioiodine therapy (RIT).

Methods

An analysis of 1371 cases was carried out: clinical and epidemiological analysis in 588 and analysis of scintigrams in 203 patients after RIT, assessment of tear production in 37 patients before RIT, rhinological status in 152 patients, genetic analysis in 59 patients, biometric analysis in 144 patients, biomechanical analysis of tears ducts in 35 patients, histological analysis in 34 patients, molecular genetic analysis of tear ducts in 30 patients.

Results

SALDO developed in 11% of cases after RIT, with a higher incidence after repeated (24%) than after single (9%) RIT.

In women receiving recombinant human thyroid-stimulating hormone, the risk of radioiodine (RI) uptake into the tear ducts was 2.35 times higher compared to the classical preparation (p = 0.007). Basal and reflex tear production were higher in patients with uptake of RI in the tear ducts (p = 0.044; 0.015). The rs231775 polymorphism increased (p = 0.041) the risk of SALDO by 2.23 times.

When compared with primary obstruction, distal obstruction occured more often in SALDO (p = 0.003), tear duct ectasia was higher (p = 0.039), and the dynamic viscosity of the lacrimal sac was different (p = 0.048). The rhinological status was not changed in the patients with SALDO.

With SALDO, in the distal parts of the tear ducts, where high expression of NIS, the iodine receptor, was shown, primary necrobiotic changes occured in the secretory epithelium of the mucous glands, obstruction of their ducts and moderate fibrosis of the surrounding tissues were observed, the proportion of elastin fibers increased relative to collagen (p = 0.029). The severity of the changes depended on the amount of RI activity.

Conclusion

SALDO occurs due to the uptake of RI from the tear fluid, and obstruction in the distal parts is characteristic, which is explained by the pathogenesis.