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Megumi Saiki, Naoko Kato, Hidemasa Torii, Ikuko Toda, Hiroyuki Arai, Murat Dogru, Kazuo Tsubota, Kazuno Negishi; Modified A-P method for intraocular lens power calculation after myopic LASIK. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4022.
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© ARVO (1962-2015); The Authors (2016-present)
To propose the modified anterior-posterior method (A-P method)* that does not require historical data to calculate intraocular lens (IOL) power for eyes after laser in situ keratomileusis (LASIK).
We have previously reported the A-P method for eyes that have undergone myopic LASIK, not requiring preoperative data (Saiki et al. 2013 JCRS). The A-P method is a modification of the double-K method using the SRK/T formula, in which the estimated pre-LASIK keratometric (K) power calculated from the post-LASIK mean posterior sagittal power of the 6-mm zone, is used for the preoperative K value in the double-K method, and the post-LASIK anterior sagittal power is used for the postoperative K value. The median of the prediction errors using the A-P method were 0.16 D, and the 25 and the 75 percentile values of the prediction error distribution were -0.27 D and +0.98 D in the spectacle plane, respectively. To reduce the prediction error using the A-P method empirically, especially to reduce the hyperopic prediction error, the results of the A-P method were shifted to 0.98 D of the myopic value, which were defined as the results of the modified A-P method. Fourteen eyes (2 eyes of 2 men, 12 eyes of 9 women) that underwent phacoemulsification and IOL implantation after myopic LASIK from a different population were included in the current study, and the accuracy of the modified A-P method was investigated retrospectively.
The mean values of the arithmetic and absolute prediction refractive errors using the modified A-P method were -0.06 ± 0.58 D (range: -1.34 to 1.05 D) and 0.41 ± 0.40 D (range: 0.01 to 1.34 D): the median values of the arithmetic and absolute prediction errors were 0.07 D and 0.30 D, respectively. The prediction errors using the modified A-P method were within ±0.5 D in 71.4 % (10 eyes) and within ±1.0 D in 85.7 % (12 eyes). These results showed that the accuracy of the modified A-P method surpassed that of the A-P method.
The modified A-P method may be a good option for calculating the IOL power in eyes undergoing cataract surgery after LASIK when the preoperative LASIK data are unavailable. * Modified double-K method for intraocular lens power calculation after excimer laser corneal refractive surgery. Saiki M et al. J Cataract Refract Surg. 2013; 39(4):556-62
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