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 coupling agent or gel to the scanning head of the probe and then moves this 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.
