Accurate corneal thickness measurement using ultrasound

In this study, we developed a faster and more accurate method for the detection of corneal thickness using an ultrasonic pulse-echo method. After a ultrasound pulse was transmitted to the cornea, the echo was received in radio frequency. 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. Based on this method, a MCS-8031 microprocessor based pachymeter for measuring corneal thickness was developed. The center frequency of the ultrasonic transducer works was 30MHz and the echoes were digitized at a 180MHz sampling frequency. The device showed an accuracy of 1 mum for 10 repeated measurements.