Ultrasonically produced hyperthermia in ophthalmology

Abstract

A series of related experimental and theoretical studies have been conducted on lesions produced in various structures of the eye by ultrasonically induced hyperthermia. Results obtained in animal eyes have been used to plan clinical treatments of various diseases. Clinical treatments of medically nonresponsive glaucoma are now in progress, and an 81% success rate has been achieved. This paper will review a theoretical model of ultrasonically induced hyperthermia. The model has been applied to the study of lesions produced in thin ocular layers by focused beams exhibiting various frequencies and beamwidths. Empirical corrections for blood flow cooling have been incorporated using data reported for related laser experiments. The model has successfully predicted the threshold values and sizes of experimental chorioretinal and scleral lesions that are useful in treating ocular disorders. In addition, the paper will describe ultrasound and thermal parameters that have been used successfully in treating human tumor transplants in nude athymic mice. [Work supported by NIH.]