An Algorithm for Accurate Measurement of Corneal Thickness Using Ultrasound RF Signal

A faster and more accurate method for the detection of corneal thickness using an ultrasonic pulse-echo technique was proposed. The corneal thickness was calculated from the time interval between the two echoes reflected at front and rear interfaces of the cornea. The time interval between two echoes was obtained by detecting the peaks of the digitized echoes. A phase-adjusting method, which is superior to the often-used interpolation approach, was used to improve the time resolution to 1/20 of the sampling period. Simulation studies showed this method is comparable to the interpolation method in accuracy at a majority of signal to noise conditions and dynamic ranges of the A/D converter but much easier to implement. The algorithm was implemented in a MCS-8031 microprocessor based pachymeter for measuring corneal thickness. The center frequency of the ultrasonic transducer was 30MHz and the echoes were digitized at a 180MHz sampling frequency. The device showed an accuracy of 1 m for ...

• Type: Journal
• Year: 2006
• Where: IJCSS
• Authors: P. J. Cao, K. Kirk Shung
• Keywords: Corneal Thickness, IJCSS 2006, Often-used Interpolation Approach, Ultrasonic Pulse-echo Technique