Encyclopedia - Ultrasound: Eye

Ultrasound, or echography, is the transmission of high frequency sound waves into the eye, which are reflected by ocular tissues and displayed on a screen so that internal structures can be visualized. The technique is often used in the evaluation of ocular structures that are obscured by cataracts, a cloudy cornea, or blood in the vitreous fluid.

The procedure itself is noninvasive and painless. The doctor places a topical anesthetic (numbing eye drop) in the eye, and then uses a small probe, called a transducer, to touch the surface of the eye. The high frequency sound waves emitted by the probe bounce back and are reproduced on a computer screen as an electronic picture of structures inside the eye.

Ultrasound is useful in the diagnosis and differentiation of intraocular tumors, orbital tumors, extraocular muscle disorders, vitreous disorders, and retinal detachment. Ultrasound also can detect lesions in the eye or orbit that otherwise may go unnoticed, and it can locate foreign bodies in the eye. One of the most common applications of ultrasound is to determine the length of the eye from the cornea to the retina. It is an important measurement in calculating the power of the intraocular lens that replaces your eye's natural lens during cataract surgery.