Background Ultrasound biomicroscopy (UBM) is a safe and non-invasive auxiliary diagnostic tool. UBM evaluation of the lacrimal drainage system (LDS) can be limited by obstacles, such as keratinised epithelium of the skin coverage and difficulty with positioning the eye cup, owing to irregularities of the medial canthus area wherein the LDS is located.

Aim To evaluate LDS in normal individuals and in different pathological conditions using UBM.

Methods UBM evaluation was carried out using a modified technique using swimming goggles with the front eye piece removed as an adjunctive device to overcome the difficulties of UBM evaluation of LDS.

Results A total of 24 normal LDS were evaluated in 12 volunteers with an age range of 14 to 54 years (mean 31.17±14.09). The lacrimal sac (LS) longitudinal diameter was always greater than the screen limits (≥15 mm), and the width varied from 1.87 mm to 3.36 mm (mean 2.56±0.43). Horizontal scanning of the LS revealed a mean cross-sectional area of 5.74 (±2.61) mm². The cross-section diameter of the canaliculi varied from 0.52 mm to 0.88 mm. LDS was also evaluated with UBM for the following disorders: chronic dacryocystitis, LS fistula, mucocoele, dacryolith, LDS with silicon tube, congenital and acquired canalicular obstruction, punctal plugs, Down's syndrome and Sjögren syndrome after permanent punctal occlusion.

Conclusions UBM is a valuable tool in the assessment of both normal and diseased LDS. It is a valuable tool in the evaluation of LDS distal to the site of complete obstruction.