B-scan Ultrasonography, often called just B-scan or Brightness scan, offers two-dimensional cross-sectional view of the eye as well as the orbit. A B-scan is used on the outside of the closed eyelid to view the eye. This type of diagnostic tool is most helpful when there is difficulty examining the eye normally. There might be lid problems that make a routine examination difficult like edema or tarsorrhaphy or severe cataracts and keratoprosthesis. A B-scan can help accurately view other eye structures like the lens, choroid, sclera, vitreous and retina. A B-scan is helpful in diagnosing retinal detachment. A B-scan is often a tool combined with an A-scan to help determine various eye abnormalities.