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Scheimpflug photography keratometry readings for routine intraocular lens power calculation
H John Shammas1, Kenneth J Hoffer, Maya C Shammas
1Department of Ophthalmology, University of Southern California, The Keck School of Medicine, Los Angeles, California, USA. hshammas@aol.com
Purpose:
To prospectively evaluate keratometry (K) values obtained by Scheimpflug photography in eyes scheduled for cataract surgery, compare the results with K values obtained with an autokeratometer (automated K), and evaluate the K values in commonly used intraocular lens (IOL) power calculation formulas for routine cataract surgery.
Setting:
Private clinical ophthalmology practice, Lynwood, California, USA.
Methods:
The mean simulated K power (simulated K), equivalent K (equivalent K), and true net power (true net K) readings from the Pentacam Comprehensive Eye Scanner were compared with the automated K readings. Automated K, simulated K, and equivalent K values were compared in commonly used IOL power calculation formulas.
Results:
The mean automated K value was 43.49 diopters (D)+/-1.75 (SD) and the mean simulated K value, 43.49+/-2.00 D (P> .1). The mean equivalent K value was 43.78+/-1.97 D and exceeded the mean automated K and simulated K by 0.29 D (P> .1). The mean true net K was 42.31+/-2.13 D, which was 1.18 D lower than the automated K and simulated K values (P= .015). The IOL prediction mean absolute error was 0.41+/-0.27 D using the automated K method, 0.50+/-0.36 D using the simulated K method (difference 0.09 D) (P> .1), and 0.65+/-0.35 D using the equivalent K method (difference 0.24 D) (P< .01).
Conclusion:
The K values from Scheimpflug photography did not improve accuracy over autokeratometer values for routine IOL power calculation.
