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Megumi Saiki, Kazuno Negishi, Murat Dogru, Naoko Kato, Hiroyuki Arai, Ikuko Toda, Ohnuma Kazuhiko, Kazuo Tsubota; Central - Peripheral Corneal Curvature Ratio No-History Method for Intraocular Lens Power Calculation after Excimer Laser Refractive Surgery. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6558.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate a new method not requiring pre-refractive surgical data for calculating the intraocular lens (IOL) power in eyes undergoing cataract surgery after myopic laser in situ keratomileusis(LASIK) and to compare the final refractive results with previously published formulae.
The double K method (Aramberri et al, 2003) using SRK/T formula was modified not to require the pre refractive surgical data. The formula was assessed in 23 eyes of 13 cataract patients after myopic LASIK. Refractive results of the current method(N), Haigis-L formula(H), Camellin-Calossi formula(C), BESSt formula with SRK/T(BS) and Hoffer Q(BH), and the Shammas method(S) were compared. In our method, the estimated pre-LASIK K-value (estimated-preKm) was used for the effective lens position calculation, and the mean anterior central K value was used for IOL power calculation by the vergence formula instead of Kpre and K post in the double K method. By independent analysis of the 57 LASIK patients, we found a significant correlation between the pre-LASIK corneal central curvature and post-LASIK corneal peripheral curvature, and derived the best-fit regression equation between them (R2=0.76, p<0.0001). The estimated-preKm was calculated from this equation.
The absolute prediction errors (ABEs) in diopters were 0.78(N), 0.85(H), 0.85(C), 1.65(BS), 1.24(BH), 1.03(S), respectively. The current method achieved the highest rate of ± 0.5 D sperical equivalent (43.5%), and had a significantly smaller ABE than with BS and BH. A postoperative uncorrected visual acuity of 20/20 and above was achieved in all cases attaining targeted emmetropia.
The current method is a new approach requiring no pre-refractive surgical data to determine IOL power in eyes undergoing cataract surgery after myopic LASIK.
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