Corneal Indentation During Ultrasonic Pachometry

Abstract

PURPOSE: This study attempted to determine whether the indentation of the cornea with an ultrasonic probe affects the corneal-thickness measurement. METHODS: A solid-tip ultrasonic transducer was mounted into the spring arm of a standard Goldmann Applanation Tonometer. Five human subjects were studied. The visual axis of each cornea was marked with a corneal marker, and the ultrasonic transducer was placed on the visual axis. Corneal-thickness measurements were made during five tension settings of the tonometer: 0, 10, 20, 40, and 80. The R-F signals were received by using a 475 Textronix oscilloscope, and the thicknesses were digitally measured. RESULTS: There was no trend for decreasing or increasing thickness measurements with increasing tension settings. CONCLUSION: Corneal-thickness measurements by ultrasonic pachometry are not significantly affected by corneal indentation with the ultrasonic probe.