Encyclopedia - Ultrasound: B-Scan

A B-scan is an ultrasound device that emits high frequency sound waves to provide a cross-sectional, two-dimensional view of eye tissue that is not visible in other ways. These sound waves are reflected by eye tissues and orbital structures and converted into electrical pulses, which are displayed on a printout as bright spots on a black background.

To perform a B-scan examination, the doctor applies a topical anesthetic, a numbing eye drop, and then moves a hand-held instrument called a transducer over the closed eyelid. As the instrument is oriented in various directions, it provides different views of the inside of the eye, which, if needed, can be recorded with a camera. Sometimes, a water bath mechanism is used to obtain good images of the anterior (front) portion of the eye. After the test, you should not rub or touch your eyes for 30 minutes, and you should arrange for transportation home.

If you are diabetic, your doctor may use the B-scan to examine your retina for retinal detachment. If you have a vitreous hemorrhage, your doctor will be unable to examine the retina visually, so he or she must rely on the B-scan to detect any abnormalities.