Comparison of Corneal Curvatures Obtained with Different Devices

ABSTRACT

PURPOSE: To evaluate device efficacy using the corneal curvature value. METHODS: Prospectively, 35 patients (70 eyes) were enrolled in the present study. Three sets of corneal curvature values were obtained using the autorefractor (RK-F1(R)), manual keratometer (OM-2(R)), partial coherence interferometry keratometer (IOL Master(R)), wavefront analyzer (KR-1W(R)), and videokeratography (Orbscan II(R)). Repeatability of each device was evaluated by coefficient of variation, standard deviation, and intraclass correlation coefficient. RM-ANOVA on ranks was used to compare the differences in corneal curvatures among the devices. The Bland-Altman plot was performed to assess measurement agreement among the devices. RESULTS: The coefficient of variation values from each device ranged from 2.92% (IOL master(R)) to 3.06% (Orbscan II(R)), and the values of intraclass correlation coefficient ranged from 0.965 (KR-1W(R)) to 0.997 (IOL master(R)). Compared with the manual keratometer, there was a maximum corneal curvature difference of 1.23 D in KR-1W(R), while the other devices had differences less than 0.82 D. CONCLUSIONS: When assessing corneal curvature, the repeatability values were similar among the 5 devices, although a difference greater than 1 D was observed when comparing the KR-1W(R) to the manual keratometer.