Ocular Ultrasound

Abstract

Ocular ultrasound is an invaluable tool for the evaluation of the eye and orbit. However, the eye and orbit are potentially sensitive to the thermal and mechanical effects of ultrasound. When performing B-mode imaging, dedicated ocular settings should be used. If these settings are not available, limiting the acoustic output to Food and Drug Administration (FDA) recommended maximum levels is strongly advised. Especially important is the acoustic output in spectral (pulsed) and color Doppler modes, which can exceed the FDA's maximum recommended levels for the eye. Adjusting settings to decrease acoustic output and limiting the time of the examination should be done when performing a Doppler examination. The acoustic output of shear wave elastography is significantly higher than FDA guidelines for the eye and should be considered experimental.

Development and evaluation of a point-of-care ocular ultrasound curriculum for medical students - a proof-of-concept study

“…The curriculum was developed bearing in mind recommendations of professional associations, recent publications and (international) university approaches to ultrasound training [ 8 , 10 , 21 , 22 , 30 , 31 , 37 , 38 ]. Interdisciplinary exchanges between ophthalmology, neurology, radiology and otorhinolaryngology also took place for this purpose to take into account the relevant issues of the different disciplines.…”

Liability, risks, and recommendations for ultrasound use in the diagnosis of obstetrics diseases

“…As a result, it has the potential to cause a wide range of changes (or “bioeffects”) in the tissues it passes through. Potentially harmful effects on tissues may be broken down into two categories: thermal and non-thermal (or mechanical) [ [54] , [55] , [56] , [57] , [58] , [59] ]. The conversion of acoustic energy into heat is an indirect cause of thermal effects caused by the propagation of a waveform.…”

A systematic review of ultrasound-mediated drug delivery to the eye and critical insights to facilitate a timely path to the clinic

“…Low (22-50 kHz) ultrasound frequencies with longer wavelengths increase the time for significant bubble growth and cavitation to occur, increasing not only the efficient translation of acoustic to mechanical energy into tissue, but the degree of tissue damage, too [103]. Comparatively, at the higher frequencies used in ophthalmic imaging (7-100 MHz) both the penetration distance and cavitating potential of the ultrasound wave are drastically reduced [104,105], which limits their application in drug delivery. When considering frequency in drug delivery, the range used depends on the application: MBP EXO applications use higher minimum frequencies compared to AS and MBP ENDO methods (0.3MHz compared to 0.02MHz) and similar maximum frequencies (3 MHz, Table 4).…”

“…Elevations in ocular temperature due to prolonged exposure to ultrasound may result in increased denaturation of plasma membrane proteins, an increase in plasma membrane fluidity, and subsequent cell lysis [43]. In addition, high intensity ultrasound has induced cataracts, corneal clouding, and lens opacification in humans, and as such these adverse effects should be assessed post-sonication [104,164]. Toxic in vitro thermal effects become apparent between 39 to 40 ºC, whilst coagulation of proteins occurs between 44 to 46 ºC and the protein constitutes of enzymes become denatured at approximately 50 ºC [163].…”