[20-MHz ultrasound of pre-saccular lacrimal ducts].

BACKGROUND: In clinical practice, ultrasound examination of the lacrimal drainage system is not able to represent the lacrimal canaliculi with a high quality but the high-resolution ultrasound with 20 MHz transducer is a better possibility to get images of the lacrimal canaliculi.

PATIENTS AND METHODS: A total of 20 patients suffering from diseases of the lacrimal drainage system were examined ultrasonographically. Detection and localisation of the lacrimal canaliculi was made by a 20 MHz sector scanner in combination with the ultrasound diagnostic system I. After patient positioning, the high-resolution ultrasound investigation was done via immersion connection (methylcellulose). Instillation of viscoelastic substances (e.g. Healon) was necessary to detect the lacrimal canaliculi.

RESULTS: In all investigated patients, the high-resolution ultrasound (transducer frequency of 20 MHz) allowed reproducible images of the lacrimal drainage system. Without viscoelastic substances, a good echographic visualisation of canaliculi structures was obtained from patients with chronic canaliculitis or dislocated punctum plugs. In chronic canaliculitis the ultrasonic images showed an ectatic canaliculus (diverticulum) and high-reflective structures (concrements).

CONCLUSION: The high-resolution ultrasound (transducer frequency of 20 MHz) seems to be well suited for investigations of the lacrimal drainage system. In comparison with ultrasound biomicroscopy the resolution is lower but the depth of penetration is higher. The use of 20 MHz ultrasonic examination can be helpful in the clinical diagnostic of chronic canaliculitis.