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Li Wang, Douglas Koch; Evaluation of new updates in IOL power calculations after LASIK/PRK. Invest. Ophthalmol. Vis. Sci. 2013;54(15):804.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the accuracy of new updates in IOL power calculations in eyes with prior LASIK/PRK.
Using data from 43 consecutive eyes, we evaluated: 1) the Shammas-PL formula, which does not use the pre-LASIK K values to predict the effective lens position, comparing it to the double-K Holladay 1 formula; 2) an OCT-based IOL calculation formula, and 3) the ORA system, which performs intraoperative aphakic measurements. The manifest refraction was obtained at 1 month or later after cataract surgery. IOL power prediction errors were calculated and the variance of the IOL prediction error was evaluated to assess the consistence of the performance of each method.
With the Atlas 4-mm zone values, the Shammas-PL formula tended to produce a smaller variance of IOL prediction error, compared to that with double-K Holladay 1 formula. Comparing to the formulas on the ASCRS calculator, the OCT-based IOL formula had the lowest refractive mean absolute error of 0.41 D, followed by the Haigis-L (0.44 D), Shammas (0.51 D), Wang-Koch-Maloney (0.57 D), and Galilei (0.65 D). In 15 eyes, the ORA tended to produce higher refractive prediction error (0.69 D) compared to OCT-based formula, Haigis-L, and Shammas (0.36 - 0.47 D).
Refinements in existing calculations and new devices improve the accuracy of IOL power prediction in post-refractive surgical eyes. The ASCRS calculator has been updated accordingly.
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