Novel Evidence Concerning Lacrimal Sac Movement Using Ultra-High-Frequency Ultrasound Examinations of Lacrimal Drainage Systems

Abstract

Purpose: Current hypothesis regarding the mechanism of active tear drainage is based on studies performed ex vivo or under nonphysiological conditions. Novel ultra-high-frequency ultrasound has the advantage of generating images with superior resolution, enabling measurements of low flow in small vessels, and the tracking of tissue motion in real time. The purpose of this study was to investigate the lacrimal drainage system and active drainage using this modality. Methods: The upper lacrimal drainage system was investigated with 40–70 MHz ultrasound in 22 eyes in 13 patients. Irrigation confirmed a lacrimal obstruction in 10 eyes. Motion tracking was used to map movement of the lateral lacrimal sac wall and to measure flow when possible. Results: The anatomy of the upper lacrimal drainage system was mapped in vivo, including the proximal canaliculi, which have not previously been imaged. The lacrimal sac lumen is slit shaped in its resting state but is distended when irrigated or if a nasolacrimal duct obstruction is present. Thus, the healthy lacrimal sac is not a cavity, and the medial retinaculum does not act against a stretched structure. Motion tracking visualized the “lacrimal pump,” showing that the direction of motion of the lateral lacrimal sac wall is mainly in the sagittal plane during blinking. Conclusions: Ultra-high-frequency ultrasound allows detailed physiological monitoring of the upper lacrimal drainage system in vivo. Our findings suggest that current theories of active tear drainage need to be reappraised.

Clinical application of ultra‐high frequency ultrasound: Discovering a new imaging frontier

“…In the first one, UHFUS could have a possible role in the detection of premature signs of breast implant ruptures. In the second one, there is currently only one study describing the anatomy of tear ducts with this technology, 57 and a field of interest could be the study of the papilla of the optic nerve.…”

UHFUS: A Valuable Tool in Evaluating Exocrine Gland Abnormalities in Sjögren’s Disease

“…It is worth noting that lacrimal glands are located superficially, even if there are currently no studies available on the use of ultra-high frequency ultrasound. Interestingly, ultra-high frequency ultrasound has been employed to assess other eye structures, such as the lacrimal drainage system, highlighting its importance and safety in evaluating ocular pathologies [28][29][30][31][32]. In addition, with conventional ultrasound, lacrimal glands can be frequently undetectable.…”