Related Experiment Video
Updated: May 10, 2026
Comparison of Agreement and Accuracy using Binocular Wavefront Optometer with Autorefractor and Phoropter
Published on: September 16, 2025
Scheimpflug corneal power measurements for intraocular lens power calculation in cataract surgery
Elie Saad1, Maya C Shammas1, H John Shammas2
1Shammas Eye Medical Center, Lynwood, California.
Purpose:
To compare the keratometric (K) readings from the Pentacam-HR (High Resolution) unit with the automated K values from the IOLMaster keratometer (KIOLM), 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 (KF), true net power (KTNP), and total refractive power (KRP) are compared with KIOLM. 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:
KF averaged 0.03-0.13 diopter (D) higher than KIOLM (P > .05), KTNP averaged 1.16-1.21 D lower than KIOLM (P > .001), and KRP averaged 0.23-0.72 D lower than KIOLM (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 KIOLM (P > .05). MedAE was lower in all categories when the pupil was 3 mm or smaller.
Conclusion:
The Pentacam KF values were the closest to KIOLM and the KF readings from the 2-mm ring yielded the best results for IOL power calculation.
