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Thread: Essential Lectures of ophthalmic ultrasound (B-scan) videos

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    Default Essential Lectures of ophthalmic ultrasound (B-scan) videos

    B-scan ultrasonography is an important adjuvant for the clinical assessment of various ocular and orbital diseases. With understanding of the indications for ultrasonography and proper examination technique, one can gather a vast amount of information not possible with clinical examination alone. This article is designed to describe the principles, techniques, and indications for echographic examination, as well as to provide a general understanding of echographic characteristics of various ocular pathologies.

    Ophthalmic ultrasonography uses high-frequency sound waves, which are transmitted from a probe into the eye. As the sound waves strike intraocular structures, they are reflected back to the probe and converted into an electric signal. The signal is subsequently reconstructed as an image on a monitor, which can be used to make a dynamic evaluation of the eye or can be photographed to document pathology.

    Sound is emitted in a parallel, longitudinal wave pattern, similar to that of light. The frequency of the sound wave is the number of cycles, or oscillations, per second, measured in hertz (Hz). For sound to be considered ultrasound, it must have a frequency of greater than 20,000 oscillations per second, or 20 KHz, rendering it inaudible to human ears. The higher the frequency of the ultrasound, the shorter the wavelength (distance from the peak of one wave to the peak of the next wave). A direct relationship exists between wavelength and depth of tissue penetration (the shorter the wavelength, the more shallow the penetration). However, as the wavelength shortens, the image resolution improves.

    Given that ophthalmic examinations require little in the way of tissue penetration (an eye being 23.5 mm long on average) and much in the way of tissue resolution, ultrasound probes used for ophthalmic B-scan are manufactured with very high frequencies of about 10 million oscillations per second, or 10 MHz. In contrast, ultrasound probes used for purposes such as obstetrics use lower frequencies for deeper penetration into the body, and, because the structures being imaged are larger, they do not require the same degree of resolution. Recently, high-resolution ophthalmic B-scan probes (ultrasound biomicroscopy or UBM) of 20-50 MHz have been manufactured that penetrate only about 5-10 mm into the eye for incredibly detailed resolution of the anterior segment.
    Essential Lectures ophthalmic ultrasound (B-scan) attachment.php?attachmentid=177&stc=1&d=1431855768

    Lecture 1: A Brief History of Ultrasound video

    Lecture 2: Basic Physical Principals of Ultrasound video

    Lecture 3: Basic Instrument Design video

    Lecture 4:How Does an A-Scan Become a B-Scan? video

    Lecture 5: Examination Techniques for the Beginner video

    Lecture 6a: Real Time video

    Lecture 6b: Gray Scale video

    Lecture 6c: 3D Thinking video

    Lecture 7: How to Approach a Diagnosis? video

    Lecture 8: Vocabulary video











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