Scheimpflug photography keratometry readings for routine intraocular lens power calculation.
OBJECTIVE
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.


METHODS
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).


CONCLUSIONS
The K values from Scheimpflug photography did not improve accuracy over autokeratometer values for routine IOL power calculation.
Shammas
H John
HJ
Department of Ophthalmology, University of Southern California, The Keck School of Medicine, Los Angeles, California, USA. hshammas@aol.com
Hoffer
Kenneth J
KJ
Shammas
Maya C
MC
D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001699:Biometry; D002387:Cataract Extraction; D003315:Cornea / Q000502:physiology*; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D007910:Lenses, Intraocular; D008297:Male; D008875:Middle Aged; D010781:Photography / Q000379:methods*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology*