Scheimpflug Corneal Power Measurements for Intraocular Lens Power Calculation in Cataract Surgery

PURPOSE: To compare the keratometric (K) readings from the Pentacam-HR (High Resolution) unit with the automated K values from the IOLMaster keratometer (K-IOLM), and to evaluate them in the commonly used intraocular lens (IOL) power calculation formulas for routine cataract surgery. DESIGN: Prospective, comparative observational study. METHODS: SETTING: Private practice, Lynwood, California. STUDY POPULATION: Fifty cataractous eyes scheduled for surgery between July and August 2012. OBSERVATION PROCEDURE: The K readings from the Pentacam-HR unit taken at the 2-, 3-, 4-, and 5-mm zones and the 2-, 3-, 4-, and 5-mm rings, respectively, from 3 different maps: sagittal corneal front (K-F), true net power (K-TNP), and total refractive power (K-RP) are compared with K-IOLM. IOL power calculations were performed with each of the 25 sets of K readings. MAIN OUTCOME MEASURES: The IOL prediction median absolute error (MedAE) obtained with each measurement. RESULTS: K-F averaged 0.03-0.13 diopter (D) higher than K-IOLM (P > .05), K-TNP averaged 1.16-1.21 D lower than K-IOLM (P > .001), and K-RP averaged 0.23-0.72 D lower than K-IOLM (P > .001), with large variations in the measurements. The MedAE obtained with the different Pentacam K readings ranged from 0.44-0.64 D vs 0.52 D obtained with K-IOLM (P >.05). MedAE was lower in all categories when the pupil was 3 mm or smaller. CONCLUSION: The Pentacam K-F values were the closest to K-IOLM and the K-F readings from the 2-mm ring yielded the best results for IOL power calculation. ((C) (C) 2013 by Elsevier Inc. All rights reserved.)