High-resolution ultrasonic imaging and characterization of the ciliary body

PURPOSE. To develop a means for noninvasive in vivo visualization of the ci liary processes using very-high-frequency (50 MHz) ultrasound and to develo p quantitative morphologic descriptors that may relate to physiologic funct ion. METHODS. The region of the ciliary body was scanned with very-high-frequenc y ultrasound, both in rabbits and in normal human subjects. Data were acqui red in a series of planes so that the spacing between them was less than th e beam width of the transducer in its focal plane. Three-dimensional perspe ctive images were constructed, representing the anatomy of the angle region , including the ciliary processes. The automatically detected boundaries of the ciliary processes were analyzed to compute their periphery, area, shap e factor, and fractal dimension. These measures were compared between the h uman and the rabbit eye and analyzed for periodicities related to the spaci ng of successive processes. RESULTS. Three-dimensional images allowed visualization of the radial arran gement of the processes. All biometric descriptors were significantly diffe rent between the rabbit and human eye and showed periodicities consistent w ith spacing between processes. CONCLUSIONS. The methods described in this report are sensitive descriptors of the state of the ciliary processes. These techniques may be of value in measurement of changes in the ciliary body associated with disease, medica l therapy, and aging.