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IOL power calculations after myopic LASIK/PRK eyes: comparison of optical coherence tomography-based formula, Barrett True K, and the ASCRS IOL power calculator

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Session Details

Session Title: Cataract Surgery Outcomes. IOL Power Calculations

Session Date/Time: Monday 07/09/2015 | 16:30-18:30

Paper Time: 16:48

Venue: Room 1

First Author: : D.Koch USA

Co Author(s): :    L. Wang   M. Tang   D. Huang              

Abstract Details


In eyes undergoing cataract surgery after myopic LASIK/PRK, to compare the optical coherence tomography-based IOL power formula (OCT), Barrett True K formula, and other methods on the ASCRS calculator.


Cullen Eye Institute, Baylor College of Medicine, Houston, TX, USA and Casey Eye Institute, Portland, Oregon, USA


In 104 consecutive eyes that had undergone cataract surgery after prior myopic LASIK/PRK, IOL calculations were performed using the OCT formula, Barrett True K, and ASCRS methods requiring no prior data. Using the actual refraction following cataract surgery as target refraction, we calculated the predicted IOL power for each method. The IOL prediction error was obtained by subtracting the predicted IOL power from the power of IOL implanted. Arithmetic IOL prediction errors, variances of mean arithmetic IOL prediction error, median refractive prediction error (RPE) and percent of eyes within 0.5 D and 1.0 D of RPE were calculated.


The median RPEs were 0.35 D, 0.43 D, 0.51 D, 0.48 D, 0.39 D, and 0.34 D, respectively, for the OCT, Barrett True K, Wang-Koch-Maloney, Shammas, Haigis-L, and Average of these 5 formulas (p < 0.05 comparing either OCT or Average to Barrett True K, Wang-Koch-Maloney, and Shammas). The % of eyes within 0.5 D of RPE were 68.3%, 57.7%, 50.0%, 52.9%, 55.8%, and 67.3%, and within 1.0 D of RPE, 92.3%, 89.4%, 86.9%, 88.5%, 90.4%, and 94.2%, respectively.


The OCT-based IOL power formula is a promising method. The ASCRS IOL power calculator has been updated to include the OCT and Barrett True K formulas.

Financial Interest:

One of the authors has significant investment interest in a company producing, developing or supplying product or procedure presented, One of the authors research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, One of the authors receives consulting fees, retainer, or contract payments from a competing company

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