Scheimpflug keratometry versus conventional automated keratometry in routine cataract surgery

Abstract

To evaluate keratometry (K) readings obtained with an automated keratometer (IOLMaster) and Scheimpflug imaging (Pentacam) in eyes having routine cataract surgery and to compare the predicted and actual refractive outcomes. Epsom/St. Helier University Hospitals, London, United Kingdom. In this retrospective study, the mean absolute prediction errors (MAEs) were obtained for automated keratometry and Scheimpflug keratometry: true net power, anterior K, and equivalent K [corrected] values for 1.0 to 7.0 mm corneal diameters. Eyes were divided into lower delta K (mean 1.15 diopters [D]) and higher delta K (mean 2.13 D) groups and lower preoperative astigmatism (mean 0.83 D) and higher preoperative astigmatism (mean 2.55 D) groups to determine notable trends. The study evaluated 29 eyes. The lowest MAE was 0.424 D +/- 0.421 (SD) for Scheimpflug equivalent [corrected] K at 3.0 mm; the second lowest was 0.452 +/- 0.359 D for automated keratometry, which had the smallest SD overall. The difference was not statistically significant. In the lower delta K and astigmatism groups, the automated keratometer had the lowest MAE and smallest standard deviation. In the higher groups, there was a trend toward increased accuracy for the Scheimpflug equivalent [corrected] K values at 3.0 mm. In this small study, Scheimpflug imaging was not superior to automated keratometry overall, but the data suggest a trend toward increased accuracy of Scheimpflug equivalent [corrected] K values in eyes with more irregular corneas. No author has a financial or proprietary interest in any material or method mentioned.