Ultrasonography or echography is a diagnostic imaging procedure that utilizes ultrasonic sound to create images of the interior of the eye. The technique is invaluable when the optical media of the eye is opaque or too dense to enable direct visualization of the back of the eye such as in severe cataract, hemorrhaging, and infection. Ultrasound may guide surgical planning for retinal detachment and trauma. Ultrasound is also used to diagnose and measure intraocular tumors.