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Abstract White cataracts and intumescent cataracts are challenging cases for almost all surgeons. In these eyes, during capsulorhexis creation, the pressure created by the hyper-hydration of lens fibers can cause spontaneous tears in the capsulorhexis that extend to the periphery. This has been termed the Argentinean Flag Sign. Once this occurs, the cataract surgery may become extremely difficult due to poor construction of the capsulorhexis, and possible rupture of posterior capsule. OCT is a non-invasive method that have the ability of in situ visualization of tissue, It became of particular importance in ophthalmology because of the key information provided by them regarding the physiology and the diseases related to the eye .The structures of the anterior segment can be analyzed using OCT .It became used increasingly due to its ability for providing a non - contact scans to the anterior segment of the eye. This makes the examination comfortable, safe and fast. The anterior segment optical coherence tomography (AS-OCT) act as a guide in determining the presence or absence of fluid pockets under the anterior capsule for stable and easy removal of subcapsular fluid pockets. The eye is a superficial fluid filled structure; ultrasound is an easy to use modality for visualization of ocular pathology and anatomy. The principles of ocular ultrasound are the same as other applications of this technology. Sound waves are generated at a frequency greater than 20,000Hz (20 kHz), and reflected back to the transducer by tissue in its path. When the sound wave returns, a Summary 58 piezoelectric crystal in the transducer vibrates, resulting in electrical impulses that are translate in to an image or other data. There are two main types of ultrasound used in ophthalmologic practice currently, A-Scan and B-scan. In A-scan or time-amplitude scan and In B-scan, or brightness amplitude scan, sound waves are generated at 10 MHz and converted into spikes that correspond with tissue interface zones. Biometry enables the measurement of the various dimensions of the eye, including axial length (AL), anterior chamber depth (ACD), lens thickness (LT) or central corneal thickness (CCT). These values, together with the keratometry are essential for the IOL power calculation. Precision of measurements is crucial, as a 0.1 mm error in AL results in a refractive error of about 0.27 diopter (D). B scan ultrasonography is the most commonly used modality for the assessment of posterior segment pathologies. Cataract is a degenerative disease of the lens. Ophthalmoscopy shows a white reflection with an opaque lens (leukocoria). In immature cataracts, scattered opacities are separated by clear zones. In a complete cataract, the lens has a completely opaque cortex; on US it is seen as a hyperechoic structure. Although cataract detection is not the primary aim of US, this technique is often routinely performed before mature cataract extraction in order to rule out possible contraindications to surgery, such as retinal or vitreous, and choroidal detachments, tumors, and other that cannot be seen on the ophthalmoscopic examination because of the cataract and could influence the choice of treatment and prognosis. |