ABSTRACTComparative experiments were performed on conventionally chemtempered lenses and ones chemtempered in an ultrasonically stimulated, slowly oscillated salt bath. With ultrasonic stimulation, a substantially shorter treatment time was found to result in greater strength and greater surface enrichment of K+ions. The K+-rich surface layer was as deep or deeper than that found in conventionally chemtempered lenses. The results suggest that the ultrasonic stimulation continually enriches the salt bath with K+ions in the region of the lens surface.