Comparison of intraocular lens calculation methods after myopic laser-assisted in situ keratomileusis and radial keratotomy without prior refractive data

Aim To compare intraocular lens (IOL) calculation methods not requiring refraction data prior to myopic laser-assisted in situ keratomileusis (LASIK) and radial keratotomy (RK). Methods In post-LASIK eyes, the methods not requiring prior refraction data were Hagis-L; Shammas; Barrett True-K no-history; Wang-Koch-Maloney; ‘average’, ‘minimum’ and ‘maximum’ IOL power on the American Society of Cataract and Refractive Surgeons (ASCRS) IOL calculator. Double-K method and Barrett True-K no-history, ‘average’, ‘minimum’ and ‘maximum’ IOL power on ASCRS IOL calculator were evaluated in post-RK eyes. The predicted IOL power was calculated with each method using the manifest postoperative refraction. Arithmetic and absolute IOL prediction errors (PE) (implanted–predicted IOL powers), variances in arithmetic IOL PE and percentage of eyes within ±0.50 and ±1.00 D of refractive PE were calculated. Results Arithmetic or absolute IOL PE were not significantly different between the methods in post-LASIK and post-RK eyes. In post-LASIK eyes, ‘average’ showed the highest and ‘minimum’ showed the least variance, whereas ‘average’ and ‘minimum’ had highest percentage of eyes within ±0.5 D and ‘minimum’ had the highest percentage of eyes within ±1.0 D. In the post-RK eyes, ‘minimum’ had highest variance, and ‘average’ had the least variance and highest percentage of eyes within ±0.5 D and ±1.0 D. Conclusion In post-LASIK and post-RK eyes, there are no significant differences in IOL PE between the methods not requiring prior refraction data. ‘Minimum’ showed least variance in PEs and more chances of eyes to be within ±1.0 D postoperatively in post-LASIK eyes. ‘Average’ had least variance and more chance of eyes within ±1.0 D in post-RK eyes.