Prediction accuracy of intraocular lens power calculation methods after laser refractive surgery

Abstract

BackgroundThis study aimed to evaluate the prediction accuracy of postoperative refractions using partial coherence interferometry (IOL-Master) and applanation ultrasound (AL-3000) assisted with corneal topography (TMS-4) in eyes that had undergone myopic laser-assisted in situ keratomileusis (LASIK).MethodsHaigis-L formula, Koch–Maloney method using Haigis formula, Shammas clinically derived K-value (simulated keratometric value) correction (Shammas c.d.) using Haigis formula, and Shammas post-LASIK (Shammas-PL) formula were used in eyes with myopic LASIK. Constants were derived from the optimized constants in 133 virgin eyes. Refractive outcomes were determined by streak retinoscopy and subjective manifest refraction. Methods and formulas were evaluated by mean error (ME), standard deviation (SD), range of error, mean absolute error (MAE), median absolute error, 95% confidence interval of MAE, and percentage of eyes within ±0.5 diopter (D), ±1.0 D, and ±1.5 D of prediction.ResultsSDs of the Haigis-L, Koch-Maloney method using the Haigis formula, Shammas c.d. using the Haigis formula, and the Shammas-PL formula using IOL-Master were 0.721, 0.695, 0.695, and 0.698; and those using AL-3000 assisted with TMS-4 were 0.782, 0.741, 0.743, and 0.778, respectively.ConclusionsNo-history methods that corrected corneal power with measurements using IOL-Master were promising in myopic post-LASIK eyes, but still a gap in prediction accuracy exists between virgin eyes and post-LASIK eyes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12886-017-0439-x) contains supplementary material, which is available to authorized users.

Prediction Accuracy of Total Keratometry Compared to Standard Keratometry Using Different Intraocular Lens Power Formulas

“…12 TK is based on actual measurements of the total cornea, which may be particularly advantageous for certain patients who may benefit from a more accurate information about their total corneal power (eg, in astigmatic or post-LASIK eyes). [4][5][6][7][8]14,15 Our results showed distinct trends after application of standard keratometry and TK data to the formulas Haigis-T, Barrett Universal II/Barrett TK Universal II, Barrett TK Toric, and the Barrett Toric Calculator. Overall, descriptive statistics showed a smaller distribution of APE for SE and cylinder when TK data were used instead of standard keratometry data.…”

“…This can be advantageous for certain patients who may benefit from more accurate information about their total corneal power (eg, in astigmatic or post-LASIK eyes). [4][5][6][7][8]14,15 TK measures the refractive power of the cornea expressed in a toric model, consisting of three values (TK1, TK2, and Ta). TK is compatible with keratometry data for normal eyes, allowing TK values to be included in classic IOL calculation formulas.…”

Accuracy of intraocular lens power calculation formulae after laser refractive surgery in myopic eyes: a meta-analysis

“…Among these, three studies did not have percentage data, 16 studies included only one of the selected formulae, five studies were hyperopic laser refractive surgery or radial keratotomy surgery. After the exclusion of these studies, 16 articles were used for analysis [5,[12][13][14][15][16][17][22][23][24][25][26][27][28][29][30].…”

Consistency evaluation of intraocular lens power calculation methods in eyes that have undergone small-incision lenticule extraction

“…Haigis-L [8], Shammas-PL [9], Camellin-Calossi [9] and Barret True K [11] formula are commonly used formulas for IOL power calculation for cornea refractive surgery eyes [9,12]. The aim of our study was to evaluate the consistency of IOL power calculations in these four different formulas for cataract surgery in eyes after SMILE, and provide a basis for the calculation of the IOL power of cataract patients after SMILE.…”

“…The consistency of Haigis-L and Shammas-PL in the four formulas is higher, indicating that the calculation of IOL can obtain relatively accurate values even without previous case data, which is more convenient for clinical calculation. And the high correlation of all the formulas demonstrated Camellin-Calossi formula and the Barret True K formula are available as a reference.Haigis-L and Shammas-PL have been widely used and shown promising results which are based on a correction of the corneal power by adjusting the keratometric index[9,12]. The use of the adjusted keratometric index is a valid and easy method to estimate the central corneal power in corneas with previous keratorefractive surgery.…”