The use of ultrasound in the evaluation of diabetic vitreoretinopathy.

A basic examination of the globe is performed with A-scan ultrasonography, and careful attention is given to the extent of vitreous opacities and areas of high reflectivity. B-scan ultrasonography then is used to delineate the topography of the disorder. A change in the patient's position while scanning may allow liquid blood to flow across the retina so that it can be displayed. Other kinetic clues are used to differentiate opacities in the vitreous from liquid blood on the retina, fibrovascular membranes, and retina itself. Finally, A-scan quantitation is used again to differentiate fibrovascular membranes from retinal detachment and the posterior surface of the posterior vitreous detachment. A careful sketch of the pathological condition is made for use in monitoring the patient or at vitrectomy.