[Imaging the lacrimal canaliculus with 20-MHz ultrasonography: a normal diagnosis (Part 1)].
BACKGROUND
High-frequency ultrasonography is used in ophthalmology with probes at 20, 30 and 50 MHz. The latter are used particularly for examining the anterior segments of the eye. The physical and acoustic parameters of the 20-MHz probes present an ideal compromise between resolution and penetration depth for examination of the lacrimal passages. These probes can be adapted to the I3 ultrasound diagnostic device, offering a clear financial advantage.


METHODS
During the ultrasound examination, the patient is in the supine position with the head back and turned away from the eye to be examined. For proper transmission, enough gel must be applied, so that the 20-MHz probe can easily navigate on the surface to be scanned. If there is no inflammation, Healon can be applied in the canal so that it is dilated and easier to visualize.


RESULTS
In all patients, we were able to visualize the canaliculi in the main cross-sections with the ultrasound. The edge of the eyelid, the lacrimal caruncle, and the medial palpebral ligament can serve as landmarks in the search for the canaliculi.


CONCLUSIONS
The 20-MHz probes are better adapted to visualizing the presaccular lacrimal passages than conventional 10-MHz probes and the 50-MHz biomicroscope, thus enhancing the spectrum of imaging methods.
Ostendorf
M
M
Clinique et Policlinique d'Ophtalmologie de l'Université Ernst-Moritz-Arndt de Greifswald, Rubenowstrabe 2, D-17489 Greifswald, Allemagne.
Tost
F
F
D004867:Equipment Design; D006801:Humans; D007765:Lacrimal Apparatus / Q000000981:diagnostic imaging*; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods