A Comparison of Axial Length, Keratometry, and Measured White-to-white Using Different Devices

PURPOSE: To compare the accuracy and clinical usefulness of various devices by measuring axial length, keratometry, and white-to-white. METHODS: In 64 eyes of 56 cataract patients, axial length was measured using Galilei™, Lenstar®, and A-scans, and keratometry was measured using Galilei™, Lenstar®, and ARK. In 86 eyes of 74 cataract patients, white-to-white was measured using Galilei™ and Lenstar®. RESULTS: The average axial length measurements using Galilei™, Lenstar®, and A-scans were significantly correlated (p < 0.001), but without a statistically significant difference (p = 0.611). The 95% agreement range was the smallest at 0.22 mm for the Lenstar® and A-scans. The average mean K using Galilei™, Lenstar®, and ARK were significantly correlated (p < 0.001), but without a statistically significant difference (p = 0.657). The 95% agreement range was relatively small at 1.83 D for Lenstar® and ARK. The average white-to-white using Galilei™ and Lenstar® were significantly correlated (p < 0.001), with a statistically significant difference (p = 0.011). The 95% agreement range was 2.20 mm. CONCLUSIONS: Axial length, keratometry, and white-to-white measured by different devices were highly correlated and were not statistically different; however, agreement was low between measurements. It is therefore important to consider these findings when using them equally.

Comparison of the Refractive Outcomes According to the Differences of Biometry and Keratometry Reading

PURPOSE: The purpose of this study was to investigate the error tendency between preoperative expected refraction and postoperative manifest refraction based on axial length, anterior chamber depth, and keratometric data obtained by an automated keratometer and Pentacam(R) in cataract surgery cases and to report how their differences affect determination of intraocular lens (IOL) power. METHODS: The authors retrospectively reviewed the medical records of 110 eyes of 84 patients who underwent cataract surgery. Axial length and anterior chamber depth were measured by A scan ultrasound biometry, while keratometric values were obtained by an automated keratometer and Pentacam(R). IOL power was calculated using the SRK/T formula. Patients were divided into 3 groups based on the axial length, anterior chamber depth, and the difference of keratometric values between the 2 devices. Refractive error was analyzed 2 months after surgery. RESULTS: There were no statistically significant differences between axial length and anterior chamber depth among the groups; however, the K reading differences were statistically significant. Although the mean absolute error (MAE) of each group showed no statistical significance among the groups, the MAE was more pronounced in the group in which the keratometeric value measured by Pentacam(R) differed more than 1.00 diopter from the automated keratometer measurements. CONCLUSIONS: There was no statistically significant difference between axial length and anterior chamber depth among the groups. A difference of 1.00 diopter or more between the keratometric values obtained by an automated keratometer and Pentacam(R) significantly affects the postoperative refractive error; therefore, these factors should be considered when determining IOL power.