Focused ultrasound concentrates a large amount of ultrasonic energy into a small focal zone. We have used new techniques to develop a transducer that creates intracorneal, thermally induced lesions in rabbit eyesin vitro.' Histologic study shows that these lesions are confined to the stroma and that the procedure causes no structural damage to the corneal epithelium or endothelium or other ocular structures. The potential uses of this device in corneal research and therapy are discussed.