Improved system for sonographic imaging and biometry of the cornea.

We developed a programmable motion system for high-frequency (50 MHz) ultrasonographic imaging of the cornea. The system permits a variety of scanning modes, including arc scans matched to the approximate radius of curvature of the cornea. This approach allows high-precision biometry (+ or - 2 microm) over a much larger region of the cornea than the 3 mm central zone obtainable with conventional rectilinear scanning. Using 60 degree wide meridional arc scans covering each clock-hour of a rabbit cornea, we obtained data over an 8 mm wide central zone and produced maps representing the thickness of the corneal epithelium.