الفهرس 
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Abstract
Ultrasound biomicroscopy is a new imaging technique that uses high frequency ultrasound to produce images of the eye at near microscopic resolution.
Fifty mega hertz is an ideal compromise between depth and resolution to visualize the entire anterior segment.
There are three main components of the ultrasound biomicroscopy machine transducer, high-frequency signal processing and precise motion control.
In ultrasound biomicroscopy the probe may be used in the supine or the sitting position and the eye is open.
Ultrasound biomicroscopy systems are suitable for imaging of virtually all anterior segment anatomy and pathology, including the cornea, iridocorneal angle, anterior chamber, iris, ciliary body and lens.
Ultrasound biomicroscopy provides objective, high resolution, cross-sectional information on the anterior segment anatomy and is sometimes useful for understanding the mechanism of glaucoma.
Several types of glaucoma are caused by structural abnormalities of the anterior segment of the globe. This is particularly true of angle closure glaucoma and infantile glaucoma. The ability of ultrasound biomicroscopy to image the anterior chamber structures in depth at high resolution makes it a useful tool in glaucoma research and clinical practice.
Ultrasound biomicroscopy is useful in analyzing angle closure glaucoma and the mechanisms that produce it. Other ocular structures that may participate in the production of angle closure can be simultaneously imaged.
Ultrasound biomicroscopy has clear advantages in visualizing the structures behind the iris, which is important for ruling out plateau iris and angle closure caused by iridociliary cysts.
Conventional methods of ultrasound biomicroscopy provide a static image of the configuration of the angle at the exact moment of examination and thus the extent of occlusion can be determined. However, appositional closure cannot be accurately distinguished from synechial closure using this conventional ultrasound biomicroscopy method. The usefulness of indentation ultrasound biomicroscopy gonioscopy for eyes with relative pupillary block is reported.
Clinical factors do not appear to discriminate well between pseudo plateau iris and plateau iris. Ultrasound biomicroscopy is extremely helpful in confirming underlying mechanism and guiding therapy.
Ultrasound biomicroscopy has shown that iridociliary cysts can sometimes lead to angle closure by mechanical anterior displacement of the iris, or even to angle closure glaucoma. Ultrasound biomicroscopy helps not only to elucidate the underlying mechanism, but also to decide on the appropriate therapeutic approach.
Ultrasound biomicroscopy can play a role in differentiation of melanoma from adenoma, medulloepithelioma and melanocytoma.
Ultrasound biomicroscopy combined with slit lamp are used to provide images consistent with accepted concepts of the pathophysiology of malignant glaucoma, which help to make an accurate diagnosis. These procedures will allow individuals at risk for the disease to be identified and successfully treated before irreversible damage to the optic nerve has occurred.
Even a very small effusion over the ciliary body without clinically detectable choroidal detachment can be detected with ultrasound biomicroscopy.
Anterior chamber angle narrowing or closure may occasionally be associated with zonular defects. Ultrasound biomicroscopy can help define the mechanism of narrowing.
Ocular ultrasound biomicroscopy findings in cystinosis are similar to that reported for plateau iris syndrome.
On ultrasound biomicroscopy findings, a wider angle and the absence of cyclodialysis are significant predictors for the subsequent development of traumatic glaucoma.
Ultrasound biomicroscopy plus gonioscopy provide a valuable way to diagnose iridocorneal endothelial syndrome. Different subtypes of iridocorneal endothelial syndrome may have different ultrasound biomicroscopy manifestations. Ultrasound biomicroscopy can help to characterize the risk of angle closure glaucoma in the fellow eye of unilateral iridocorneal endothelial syndromes.
Various types of open angle glaucoma have been examined by ultrasound biomicroscopy. In certain types of open angle glaucoma such as pigmentary glaucoma, ultrasound biomicroscopy can play a much greater role.
Ultrasound biomicroscopy allows examination and measurement of the height of the trabecular meshwork. The presence of juvenile primary open angle glaucoma is suspected in eyes with a trabecular meshwork axial length ratio of less than the median value for normal eyes.
Ultrasound biomicroscopy is more sensitive than slit lamp biomicroscopy and gonioscopy in detecting anterior chamber silicone emulsification.
In aphakic glaucoma ultrasound biomicroscopy reveals a short ciliary process and flattened pars plicata after lensectomy. These findings are not present preoperatively and may have occurred because the tension of the zonules of Zinn is absent in the process of the eye growth. Ultrasound biomicroscopy also reveals membranous tissues behind the iris. These tissues may be formed by long term inflammation of the anterior segment from residual lens cortex or capsules.
Surgical iridectomy sites generally show a smooth edged gap in the iris on Ultrasound biomicroscopy. Yttrium argon garnet laser iridotomy is imaged as a much more irregular opening, with stromal disruption.
Ultrasound biomicroscopy has proved to be a useful tool to study chronic hypotony after glaucoma filtering surgery & facilitates the detection of supraciliary and suprachoroidal fluid.
The presence of a scleral chamber and absence of a subconjunctival filtering bleb are the usual ultrasound biomicroscopy findings in eyes with adequate control of intraocular preasure several months after viscocanalostomy.
In deep sclerectomy with collagen implant the ultrasound biomicroscopy findings confirm that the intraocular pressure lowering occurs by aqueous filtration through the thin remaining trabeculo-Descemetic membrane to an area under scleral flap. This is maintained open by the collagen implant.
Morphological investigation by ultrasound biomicroscopy enables to delineate a possible mechanism of action of deep sclerectomy with RHAI.
Ultrasound biomicroscopy has a value in detecting iris blockage of Ahmed tubes in the presence of corneal edema. Ultrasound biomicroscopy is instrumental in diagnosing the presence and cause of tube obstruction