الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Evaluation of the posterior segment by optical methods requires transparency of ocular media. Ultrasonic techniques are not dependant on this condition. And also exact pathological anatomy of the interior of the eye can be demonstrated by ultrasound allowing the choice of proper type of surgery and entry site. Ultrasound helps in quantitative assessment of the density of the vitreous membranes that it will be correlated with the toughness of the membranes at surgery, so ultrasound is the most useful technique in the investigations of patients waiting for vitrectomy. Ultrasound is helpful in diagnosis of retinal detachment but a small retinal tear could not be detected by ultrasound expect if there is a vitreal membranes attached to the retina which could be the possible site of a small retinal tear. Also it has great value in differentiation the retinal detachment versus posterior vitreous detachment. First the posterior insertion of the membrane should be carefully assessed with B-scan, second the presence of a second membrane either anterior or posterior to the membrane in question, thirdly with A-scan technique, the vitreous membranes and retinal detachments have different reflectivities in the periphery, finally in kientic echography, typically shows after movement of a posterior vitreous detachment on B-scan which is helpful.