Since the development of A- and B-scan ultrasound technique in the 1950s, significant progress in ophthalmic ultrasound has appeared. As the technology advances and ultrasound systems improve their ability to acquire and detect ultrasonic signals and to analyze them in terms of a spatial resolution and frequency distribution, there is no doubt that the extent of clinical applications will expand accordingly. Nevertheless, the fundamental physical restrictions of ultrasonography and Doppler will always remain the same. For ophthalmology, we hope that less expensive color Doppler systems with specifically designed probes, improved two-dimensional resolution, and Doppler spectrum acquisition will become more widely available. Because CDI allows for the first time a noninvasive assessment of the retrobulbar vasculature, we feel that many applications of this technology will develop for ophthalmology.