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

Abstract

AimTo compare intraocular lens (IOL) calculation methods not requiring refraction data prior to myopic laser-assisted in situ keratomileusis (LASIK) and radial keratotomy (RK).MethodsIn 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.ResultsArithmetic 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.ConclusionIn 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.

Prediction accuracy of no-history intraocular lens formulas for a diffractive extended depth-of-focus intraocular lens after myopic corneal refractive surgery

“…29 However, in eyes with AL <28.0mm, the results of this study were comparable with those of Lwowski et al The differences in the AL range and differing measurement devices might explain the differences. Similar to Patel et al, the average IOL power in this study gave less variance and a higher percentage of eyes within a PE within ±1 D. 32…”

“…29 However, in eyes with AL <28.0mm, the results of this study were comparable with those of Lwowski et al The differences in the AL range and differing measurement devices might explain the differences. Similar to Patel et al, the average IOL power in this study gave less variance and a higher percentage of eyes within a PE within ±1 D. 32 This study had several limitations. First, the lens constants were not optimized because of the relatively small amount of cataract patients with a history of myopic corneal refractive surgery.…”

IOL Power Calculation and Cataract Surgery in Eyes with previous Small Incision Lenticule Extraction

“…The Kruskal-Wallis test was employed to assess the differences in PE between formulae and ray tracing. In addition, the variance of ME was calculated -a smaller variance indicates better consistency of a IOL calculation method 31 . Fisher's exact test with Bonferroni correction was used to test for statistically signi cant differences between proportions of eyes with PEs within ±0.50D and ±1.00D, respectively., A p-value of <0.05 was de ned as indicative of statistical signi cance.…”

Comparative clinical accuracy analysis of the newly developed ZZ IOL and four existing IOL formulas for post-corneal refractive surgery eyes

“…A recent study in patients after corneal refractive surgery revealed that the Barrett True-K formula was superior to the Haigis-L formula [9]. In addition, techniques not requiring prior refraction data (Haigis-L; Shammas; Barrett True-K nohistory; Wang-Koch-Maloney; 'average', 'minimum' and 'maximum' IOL power on the ASCRS IOL calculator) showed no significant differences in IOL PE for post-LASIK eyes [10]. A robust study assessing the accuracy of 12 IOL power formulas and revealed that the Olsen and Barrett formulas have excellent accuracy for overall eyes [11].…”