Corneal mechanical sensitivity measurement using a staircase technique.
PURPOSE: To determine the repeatability of an unequal staircase technique (Garcia-Perez Staircase, GPS) to measure corneal mechanical threshold using the CRCERT-belmonte Aesthesiometer, and to compare this with a previously-reported psychophysical method (method of constant stimuli, MOCS). METHODS: The GPS, utilising unequal ascending and descending steps, was used to obtain a threshold measurement from the mean of six response reversals. repeatability was determined for the GPS and MOCS methods (N = 14), and threshold results obtained with each method were compared (N = 10). RESULTS: The GPS (65.0 +/- 16.9 mL min(-1); CoR +/- 18.3 mL min(-1)) method was more repeatable than the MOCS (64.0 +/- 15.7 mL min(-1); CoR +/- 37.3 mL min(-1)) and the absolute values obtained with the two methods were not significantly different. CONCLUSIONS: Although each method gave equivalent threshold results, the GPS method was more repeatable and quicker to apply and hence should reduce the influence of patient fatigue and help to minimise possible carry-over effects.