Analysis of Waveform-Derived ORA Parameters in Early Forms of Keratoconus and Normal Corneas

PURPOSE: To evaluate the Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments, Depew, NY) performance in differentiating grades I and II keratoconus from normal corneas using 41 parameters individually and to assess the effect of analyzing all parameters together. METHODS: This study compared the mean value of 41 ORA parameters in grades I and II keratoconus with healthy age-matched control eyes. Only eyes with a central corneal thickness between 500 and 600 µm were included. The area under the receiver operating characteristic curve was calculated for each of the 41 parameters independently and for all of the parameters