Intraocular Lens Power In Eyes Research Articles

Accuracy of formulas for intraocular lens power for eyes undergoing descemet stripping automated endothelial keratoplasty and cataract surgery.

To compare accuracy in intraocular lens (IOL) power calculation in eyes undergoing combined cataract and Descemet stripping and automated endothelial keratoplasty (C-DSAEK) surgery of the following formulas: Barrett Universal II, EVO, Haigis, Hoffer Q, Holladay 2, Kane and SRK/T. 72 eyes from 72 patients (38 males, (53%)) with a mean age 68.08 ± 8.69 years (from 44 to 88 years old) underwent combined C-DSAEK were included. The IOL powers to implant were calculated with Barrett Universal II formula targeting -1 D refraction. Preoperative and postoperative data were used to obtain the median of absolute prediction errors (MAE) targeting emmetropia with every tested formula. Means of MAE calculated were +1.45 D for Barrett Universal II, +1.37 D for EVO, +1.48 D for Haigis, +1.38 D for Hoffer Q, +1.37 D for Holladay 2, +1.39 D for Kane and +1.31 D for SRK/T. SRK/T MAE showed major significant (p < 0.01) differences compared to the other formulas. Even if tested formulas are not able to accurately target emmetropia, SRK/T seems to be able to provide closer results in eyes undergoing C-DSAEK.

Retrospective assessment of accuracy of nine intraocular lens power calculation formulae in eyes with axial myopia.

To compare the accuracy of nine conventional and newer-generation formulae in calculating intraocular lens power in eyes with axial myopia. Tertiary eye care center, Bengaluru, India. Retrospective cross-sectional, comparative study conducted in India. Patients undergoing uneventful phacoemulsification in eyes with axial length >26 mm were included. Preoperative biometry was done using Lenstar LS 900 (Haag-Streit AG, Switzerland). Single eye of patients undergoing bilateral implantation was randomly selected. Optimized lens constants were used to calculate the predicted postoperative refraction of each formula, which was then compared with the actual refractive outcomes to give the prediction errors, following which subgroup analysis was performed. The Kane formula, Barrett universal II, Emmetropia Verifying Optical (EVO) 2.0, Hill Radial Basis Function (Hill RBF) 3.0, Olsen formula, along with Wang Koch-adjusted four formulae, that is, Sanders Retzlaff Kraff/Theoretical (SRK/T), Holladay 1, Haigis, and Hoffer Q formula, were compared for intraocular lens power calculations. One hundred and sixty-five eyes that fulfilled all the inclusion criteria were studied. Hill RBF 3.0 had the lowest mean and median absolute prediction errors (0.355 and 0.275, respectively) compared to all formulas. In subgroup analysis (26-28, >28-30, and >30 mm), significant difference was seen only in extremely long eyes (>30 mm). The Hill RBF 3.0 formula generated the maximum percentage of eyes with refractive errors within ±0.25, ±0.5, ±0.75, and ±1 D (46%, 76.2%, 89.9%, and 95.8%, respectively). This is the first study evaluating all the formulas exclusively in the myopic eyes. Hill RBF 3 was found to be superior in accuracy to all other formulas.

Comparison of Biometric Formulae for Intra Ocular Lens Power Calculation

Purpose: To determine the accuracy of different biometric formulae for intraocular lens power (IOL) calculation in predicting a target postoperative refraction within ± 1.0 diopters in patients with long axial length undergoing phacoemulsification. Study Design: Cross sectional study. Place and Duration of Study: Department of Ophthalmology and visual sciences, Unit 1 Dow University of Health Sciences, Dr. Ruth KM Phau Civil Hospital Karachi from February 2019 to August 2019. Methods: The study included 45 eyes with cataract and preoperative uncorrected visual acuity ranging from 6/60-6/12, axial length of 24.5 to 27.0 mm with no other ocular problem. IOL power was calculated with SRK-T, Holladay 1 and Haigis formula installed in optical biometer AL-Scan (Nidek Co, Ltd., Gamagori, Japan) and by Barrett universal 2 formula from http://www.apacrs.org/barrett_universal2/. Patients underwent phacoemulsification by single surgeon. Follow up included refractive status using Autorefractokertometer, URK-700 (Unicos Co., Ltd., Korea) at 6th week post-operatively. Deviation of actual postoperative refraction from the predicted target preoperative refraction were calculated and values within ± 1.0 diopter were considered accurate. Data was analyzed using SPSS version 22. Results: Outcome in terms of postoperative refractive error (+1D to -1D) with respect to biometric formula showed 100% accuracy using Haigis formula, 90% accuracy using SRK-T formula, 72.72% accuracy using Barrett universal II formula and 66.67% accuracy using Holladay-1 formula. Conclusion: Haigis formula proved to be more reliable and accurate than SRK-T, Holladay 1 and Barrett universal II formulae for calculation of intraocular lens power in eyes with long axial length.

Effect of pupil dilation on biometry measurements and intraocular lens power in eyes with high myopia.

The present study sought to evaluate the effects of pupil dilation on ocular parameter measurements and intraocular lens (IOL) power calculation using IOLMaster in highly myopic cataract patients. A total of 233 eyes were included in this prospective study and assigned to four groups based on range of axial length (AL) as follows: group A:26-28 mm, group B:28-30 mm, group C:30-32 mm, and group D:32-36 mm. Flattest and steepest keratometry (K1 and K2), AL, anterior chamber depth (ACD), lens thickness (LT), and white-to-white (WtW) were determined using IOLMaster before and after administration of topical tropicamide. The corresponding IOL powers were calculated using Sanders-Retzlaff-Kraff/theoretical (SRK/T), Haigis, and Barrett Universal II formulas. Variations in AL, K1 and K2 following dilation were not significant (P > 0.05 in all groups). The results showed that ACD increased significantly after dilation (P = 0.000 in all groups), whereas LT decreased significantly after dilation (P = 0.000, 0.000, 0.001, and 0.003). Post-dilation WtW increased significantly in Group A, B, and C (P = 0.001, 0.001, and 0.025) but not in Group D. When IOL power was calculated as a discrete variable, significant differences were observed between pre- and post-dilation IOL power. Pupil dilation in cataract eyes with high myopia does not cause significant changes in AL and K. However, it significantly increases ACD as well as WtW values and significantly decreases the LT value. Surgeons should evaluate the effect of pupil dilation on IOL power prediction as the present findings show extreme cases. Notably, Barrett Universal II formula had the best concordance between different pupil conditions in long eyes.

Management of refractive surprise after phacoemulsification due to a decentered laser-assisted in situ keratomileusis zone

A 39-year-old male with prior history of having undergone laser-assisted in situ keratomileusis (LASIK) in both eyes was referred for management of refractive surprise of +5.0 diopter following phacoemulsification with intraocular lens (IOL) implantation in the left eye. The IOL power was re-calculated using post-LASIK IOL power formulae, but it did not differ significantly from that of the implanted IOL. Topography in the left eye showed decentration of the laser ablation zone and mild ectasia. An IOL exchange was performed in the following steps: IOL extraction, postoperative aphakic refraction to calculate IOL power, and IOL implantation. Postoperatively, there was no refractive surprise. In the right eye, the IOL power was calculated using post-LASIK IOL power formulae, which did not result in postoperative refractive surprise. Our experience highlights the efficiency of aphakic refraction over post-LASIK IOL power formulae in predicting IOL power in eyes with decentered laser ablations.

Development of a New Method for Calculating Intraocular Lens Power after Myopic Laser In Situ Keratomileusis by Combining the Anterior-Posterior Ratio of the Corneal Radius of the Curvature with the Double-K Method.

Background: A new method, the Iida–Shimizu–Shoji (ISS) method, is proposed for calculating intraocular lens (IOL) power that combines the anterior–posterior ratio of the corneal radius of the curvature after laser in situ keratomileusis (LASIK) and to compare the predictability of the method with that of other IOL formulas after LASIK. Methods: The estimated corneal power before LASIK (Kpre) in the double-K method was 43.86 D according to the American Society of Cataract and Refractive Surgery calculator, and the K readings of the IOL master were used as the K values after LASIK (Kpost). The factor for correcting the target refractive value (correcting factor [C-factor]) was calculated from the correlation between the anterior–posterior ratio of the corneal radius of the curvature and the refractive error obtained using this method for 30 eyes of 30 patients. Results: Fifty-nine eyes of 59 patients were included. The mean values of the numerical and absolute prediction errors obtained using the ISS method were −0.02 ± 0.45 diopter (D) and 0.35 ± 0.27 D, respectively. The prediction errors using the ISS method were within ±0.25, ±0.50, and ±1.00 D in 49.2%, 76.3%, and 96.6% of the eyes, respectively. The predictability of the ISS method was comparable to or better than some of the other formulas. Conclusions: The ISS method is useful for calculating the IOL power in eyes treated with cataract surgery after LASIK.

Comparison of prediction accuracy of five different biometric formulas

ABSTRACT Objective To compare the performance of Sanders-Retzlaff-Kraft/Theoretical, Hoffer Q, Barrett Universal II, Kane, and Hill-radial basis function formulas to calculate intraocular lens power in eyes with normal axial length, in terms of predicting target refraction by using partial coherence interferometry technology. Methods Phacoemulsification and intraocular lens implantation were performed in 135 eyes of 135 patients with an axial length between 22 and 24.5 mm. Axial length, keratometry, and anterior chamber depth were measured by intraocular lens Master 500. Sanders-Retzlaff-Kraft/Theoretical, Hoffer Q, Barrett Universal II, Kane, and Hill-radial basis function formulas were used for intraocular lens power calculations. The difference between the expected postoperative refraction and the mean absolute prediction error was calculated for each eye. Statistical significance was evaluated at the level of p 0.05). Conclusion The study showed the third-generation (Sanders-Retzlaff-Kraft/Theoretical and Hoffer Q), fourth-generation (Barrett Universal II) and new-generation (Kane and Hill-radial basis function) intraocular lens power calculation formulas had similar performances regarding calculation of intraocular lens power to predict target refraction after phacoemulsification in eyes with normal axial length.

Comparisons of intraocular lens power calculation methods for eyes with previous myopic laser refractive surgery: Bayesian network meta-analysis.

To compare the accuracy of the methods for calculation of intraocular lens (IOL) power in eyes with previous myopic laser refractive surgery. EENT Hospital of Fudan University, Shanghai, China. Network meta-analysis. A literature search of MEDLINE and Cochrane Library from January 2000 to July 2019 was conducted for studies that evaluated methods of calculating IOL power in eyes with previous myopic laser refractive surgery. Outcomes measurements were the percentages of prediction error within ±0.50 diopters (D) and ±1.00 D of the target refraction (% ±0.50 D and % ±1.00 D). Traditional and network meta-analysis were conducted. Nineteen prospective or retrospective clinical studies, including 1217 eyes and 13 calculation methods, were identified. A traditional meta-analysis showed that compared with the widely used Haigis-L method, the Barrett True-K formula, optical coherence tomography (OCT), and Masket methods showed significantly higher % ±0.50 D, whereas no difference was found in the % ±1.00 D. A network meta-analysis revealed that compared with the Haigis-L method, the OCT, Barrett True-K formula, and optiwave refractive analysis (ORA) methods performed better on the % ±0.50 D, whereas the Barrett True-K formula and ORA methods performed better on the % ±1.00 D. Based on the performances of both outcomes, the Barrett True-K formula, OCT, and ORA methods showed highest probability to rank the top 3 among the 13 methods. The Barrett True-K formula, OCT, and ORA methods seemed to offer greater accuracy than others in calculating the IOL power for postrefractive surgery eyes.

Comparison of the accuracy of intraocular lens power calculation formulas for eyes after corneal refractive surgery.

In cataract surgery, calculating intraocular lens (IOL) power in patients who have previously received corneal refractive surgery on the same eye presents a clinical challenge. This study aims to compare the accuracy of the Haigis-L, Barrett True-K, and Shammas-PL formulas in predicting the IOL power in eyes following corneal refractive surgery. This study analyzed 32 eyes belonging to 28 patients who underwent cataract surgery and IOL implantation after previously undergoing myopic corneal refractive surgery. The IOL power was calculated using the Haigis-L, Barrett True-K, and Shammas-PL formulas, and the accuracy of the three formulas was compared. The Haigis-L, Barrett True-K, and Shammas-PL formulas had a mean arithmetic IOL prediction error of -0.65, -0.39, and -0.46, respectively. The mean numerical errors of the three formulas were significantly different from zero (P<0.001). The smallest median absolute refraction prediction error (median =0.40) belonged to the Barrett True-K formula, which was significantly smaller than that of the Haigis-L formula (median =0.57, P<0.05) but similar to that of the Shammas-PL formula (median =0.49, P>0.05). There was no significant difference in the percentage of eyes within either ±0.50 D or ±1.00 D of the predicted refraction error across the three formulas. The Barrett True-K formula can predict IOL power in eyes that have previously undergone myopic corneal refractive surgery better than the Haigis-L formula.

Network Meta-analysis of No-History Methods to Calculate Intraocular Lens Power in Eyes With Previous Myopic Laser Refractive Surgery.

To systematically compare and rank the predictability of no-history intraocular lens (IOL) power calculation methods after myopic laser refractive surgery. PubMed, Embase, the Cochrane Library, and the U.S. trial registry (www.ClinicalTrial.gov) were used to systematically search trials published up to August 2019. Included were case series studies reporting the following outcomes in patients with cataract undergoing phacoemulsification after laser refractive surgery: percentage of eyes with a refractive prediction error (PE) within ±0.50 and ±1.00 diopters (D), mean absolute error (MAE), and median absolute error (MedAE). A network meta-analysis was conducted using the STATA software version 13.1 (STATACorp LLC). Nineteen studies involving 1,098 eyes and 19 formulas were identified. A network meta-analysis for the percentage of eyes with a PE within ±0.50 D found that ray-tracing (Okulix), intraoperative aberrometry (Optiwave Refractive Analysis [ORA]), BESSt, and Seitz/Speicher/Savini (Triple-S) (D-K SRK/T), and Fourier-Domain OCT-Based formulas were more predictive than the Wang/Koch/Maloney, Shammas-PL, modified Rosa, Ferrara, and Equivalent K reading at 4.5 mm using the Double-K Holladay 1 formulas. With regard to ranking, the top four formulas as per the surface under the cumulative ranking curve (SUCRA) values for the percentage of eyes with a PE within ±0.50 D were the Okulix, ORA, BESSt, and Triple-S (D-K SRK/T). With regard to MAE, the ORA showed lower errors when compared to the Shammas-PL formula. In this regard, the top four formulas based on the SUCRA values were the Triple-S, BESSt, ORA, and Fourier-Domain OCT-Based formulas. The SToP (SRK/T), ORA, Fourier-Domain OCT-Based, and BESSt formulas had the lowest MedAE. Considering all three outcome measures of highest percentages of eyes with a PE within ±0.50 and ±1.00 D, lowest MAE, and lowest MedAE, the top three no-history formulas for IOL power calculation in eyes with previous myopic corneal laser refractive surgery were: ORA, BESSt, and Triple-S (D-K SRK/T). [J Refract Surg. 2020;36(7):481-490.].

New method for intraocular lens power calculation using a rotating Scheimpflug camera in eyes with corneal refractive surgery

To introduce and evaluate a refraction-based method for calculating the correct power of the intraocular lens (IOL) in eyes with corneal refractive surgery and to compare the results here to previously published methods. Retrospective review of medical records was done. Group 1 was used to derive two formulas. From the relevant IOL calculation and postoperative refractive data, the refraction-derived K values (Krd) were calculated using a linear regression analysis. The values obtained with the two formulas were compared to previously published methods in group 2 to validate the results. The following methods were evaluated: Haigis-L, Barrett True-K (no history), Potvin-Hill, BESSt 2, Scheimpflug total corneal refractive power (TCRP) 4 mm (Haigis), Scheimpflug total refractive power (TRP) 4 mm (Haigis), modified Scheimpflug TCRP 4 mm (Haigis), and modified Scheimpflug TRP 4 mm (Haigis). The modified TCRP 4 mm Krd (Haigis) had good outcomes, with 60% and 90% of eyes within ±0.50 D and ±1.00 D of the refractive target, respectively. A new method using modified Scheimpflug total corneal refractive power in the 4.0 mm zone appeared to be an accurate method for determining IOL power in eyes with corneal refractive surgery.

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

BackgroundTo compare the accuracy of intraocular lens power calculation formulae after laser refractive surgery in myopic eyes.MethodsWe searched the databases on PubMed, EMBASE, Web of Science and the Cochrane library to select relevant studies published between Jan 1st, 2009 and Aug 11th, 2019. Primary outcomes were the percentages of refractive prediction error within ±0.5 D and ±1.0 D.ResultsThe final meta-analysis included 16 studies using seven common methods (ASCRS average, Barrett True-K no history, Double-K SRK/T, Haigis-L, OCT formula, Shammas-PL, and Wang-Koch-Maloney). ASCRS average yielded significantly higher percentage of refractive prediction error within ±0.5 D than Haigis-L, Shammas-PL and Wang-Koch-Maloney (P = 0.009, 0.01, 0.008, respectively). Barrett True-K no history also yielded significantly higher percentage of refractive prediction error within ±0.5 D than Shammas-PL and Wang-Koch-Maloney (P = 0.01, P < 0.0001, respectively), and a similar result was found when comparing OCT formula with Haigis-L and Shammas-PL (P = 0.03, P = 0.01, respectively).ConclusionThe ASCRS average or Barrett True-K no history should be used to calculate the intraocular lens power in eyes after myopic laser refractive surgery. The OCT formula if available, can also be a good alternative choice.

Validation of the SToP formula for calculating intraocular lens power in eyes with previous myopic excimer laser surgery

To validate the accuracy of the SToP formula for calculating the intraocular lens (IOL) power from measurements obtained with a rotating Scheimpflug camera (Pentacam) in eyes with previous myopic excimer laser surgery. IRCCS - Fondazione Bietti, Rome, Italy. Retrospective case series. Corneal curvature measurements were taken in eyes that had cataract surgery after myopic excimer laser surgery. Values from both versions of the SToP calculator (based, respectively, on the Holladay 1 and the SRK/T formulas) were compared with historical (Masket and Savini) and no-history methods (Barrett True-K, BESSt formula, equivalent K-readings, Triple-S, and Shammas). Fifty eyes of 50 patients with historical data were analyzed. The SToP formula based on the SRK/T achieved the lowest median absolute error (MedAE) (0.31 diopters [D]) and a higher percentage of eyes (62%) with a prediction error in refraction within ±0.5 D. Excellent outcomes were also achieved with the Masket method, the BESSt formula, the Savini method, and the Triple-S method, which led to similar MedAEs (from 0.31 to 0.37 D) and an even higher percentage of eyes with a prediction error within ±0.5 D (from 64% to 76%). The SToP formula based on the Holladay 1 was slightly less accurate. Several methods based on Scheimpflug camera measurements were used to successfully calculate the IOL power in eyes with previous myopic excimer laser surgery. The SToP formula based on the SRK/T was one of the best choices.

ASCRS calculator formula accuracy in multifocal intraocular lens implantation in hyperopic corneal refractive laser surgery eyes

To evaluate the accuracy of different intraocular lens (IOL) power calculation formulas available on the American Society of Cataract and Refractive Surgery calculator in calculating multifocal IOL power in eyes with previous hyperopic corneal refractive laser surgery. Retrospective case series. Amsterdam University Medical Center, University of Amsterdam, and Retina Total Eye Care, Driebergen, the Netherlands. This study compared the accuracy of 3 formulas using historical refractive data (ie, Masket, modified Masket, and Barrett True-K) and 3 formulas using no previous refractive data (ie, Shammas, Haigis-L, and Barrett True-K no-history). Sixty-four eyes were included. The variance of the prediction error of the various formulas was similar and ranged from 0.27 D2 to 0.33 D2 (P=.99). The modified Masket formula had a significantly higher median absolute prediction error than the Masket formula, Barrett True-K formula, and mean value of all formulas (P<.001). All formulas showed comparable accuracy in predicting IOL power in eyes after hyperopic corneal refractive laser surgery except for the modified Masket formula, which performed less accurately than the Masket formula, Barrett True-K formula, and mean value of all formulas.

Accuracy of the Barrett True-K formula for intraocular lens power prediction after laser in situ keratomileusis or photorefractive keratectomy for myopia

To compare the accuracy of the Barrett True-K formula with other methods available on the American Society of Cataract and Refractive Surgery (ASCRS) post-refractive surgery intraocular lens (IOL) power calculator for the prediction of IOL power after previous myopic laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, and private practice, Mesa, Arizona, USA. Retrospective case series. The accuracy of the Barrett True-K formula was compared with the Adjusted Atlas (4.0 mm zone), Masket, modified-Masket, Wang-Koch-Maloney, Shammas, and Haigis-L methods to calculate IOL power. A separate analysis of 2 no-history methods (Shammas and Haigis-L) was performed and compared with the Barrett True-K no-history option. Eighty-eight eyes were available for analysis. The Barrett True-K formula had a significantly smaller median absolute refraction prediction error than all other formulas except the Masket, smaller variances compared with the Wang-Koch-Maloney, Shammas, and Haigis-L, and a greater percentage of eyes within ±0.50 diopter (D) of predicted error in refraction compared with the Adjusted Atlas, Masket, and modified Masket methods (all P < .05). In eyes with no historical data, the Barrett True-K no-history formula had a significantly smaller median absolute refraction prediction error and a greater percentage of eyes within ±0.50 D of the predicted error in refraction than the Shammas and the Haigis-L formulas (both P < .05). The Barrett True-K formula was either equal to or better than alternative methods available on the ASCRS online calculator for predicting IOL power in eyes with previous myopic LASIK or PRK.

Accuracy of Intraocular Lens Power Formulas Involving 148 Eyes with Long Axial Lengths: A Retrospective Chart-Review Study.

Purpose. This study aims to compare the accuracy of intraocular lens power calculation formulas in eyes with long axial lengths from Chinese patients subjected to cataract surgery. Methods. A total of 148 eyes with an axial length of >26 mm from 148 patients who underwent phacoemulsification with intraocular lens implantation were included. The Haigis, Hoffer Q, Holladay 1, and SRK/T formulas were used to calculate the refractive power of the intraocular lenses and the postoperative estimated power. Results. Overall, the Haigis formula achieved the lowest level of median absolute error 1.025 D (P < 0.01 for Haigis versus each of the other formulas), followed by SRK/T formula (1.040 D). All formulas were least accurate when eyes were with axial length of >33 mm, and median absolute errors were significantly higher for those eyes than eyes with axial length = 26.01–30.00 mm. Absolute error was correlated with axial length for the SRK/T (r = 0.212, P = 0.010) and Hoffer Q (r = 0.223, P = 0.007) formulas. For axial lengths > 33 mm, eyes exhibited a postoperative hyperopic refractive error. Conclusions. The Haigis and SRK/T formulas may be more suitable for calculating intraocular lens power for eyes with axial lengths ranging from 26 to 33 mm. And for axial length over 33 mm, the Haigis formula could be more accurate.

特殊な角膜形状眼の眼内レンズ度数決定

特殊な角膜形状眼の眼内レンズ度数決定

Comparison of intraocular lens power calculation methods after myopic laser refractive surgery without previous refractive surgery data

To compare the accuracy of intraocular lens (IOL) power calculation methods for post-myopic excimer laser surgery patients without previous refractive surgery data using the Holladay IOL Consultant Program and the American Society of Cataract and Refractive Surgery (ASCRS) IOL Power Calculator. Wang Vision Cataract and LASIK Center, Nashville, Tennessee, USA. Case series. Eight methods were used to calculate IOL power: Holladay 2 partial coherence interferometry (PCI)-K, Holladay 2 FlatK, Wang-Koch-Maloney, Shammas No-History, Haigis-L, ASCRS-Average, ASCRS-Min, and ASCRS-Max. The optimum IOL power corresponding to the target refraction was back-calculated using the stable post-cataract surgery refraction and implanted IOL power. Using the optimum IOL power, the predicted IOL power error and the resultant refractive error with each method were calculated and compared. The Holladay 2 FlatK method was most accurate for IOL power calculation, followed by the Holladay 2 PCI-K, ASCRS-Min, Wang-Koch-Maloney, ASCRS-Average, Shammas No-History, Haigis-L, and ASCRS-Max. Statistically significant differences were observed between Holladay 2 FlatK and Holladay 2 PCI-K (P<.05), Wang-Koch-Maloney and ASCRS-Average (P<.05), and Haigis-L and ASCRS-Max (P<.01). No statistically significant differences were observed between the Holladay 2 PCI-K, ASCRS-Min, and Wang-Koch-Maloney or between the ASCRS-Average, Shammas No-History, and Haigis-L (both P>.05). The Holladay 2 FlatK method provided the most accurate IOL power in eyes without previous myopic laser surgery data. If the Holladay IOL Consultant Program is unavailable, the ASCRS methods can be used; the ASCRS-Min represents the most accurate method.

The Accuracy of the Double-K Adjustment for Third-Generation Intraocular Lens Calculation Formulas in Previous Keratorefractive Surgery Eyes

To evaluate the effect of the double-K (DK) modification on third-generation formulas. Thirty-eight previously myopic and 24 previously hyperopic eyes that underwent phacoemulsification with intraocular lens (IOL) insertion after Laser in situ keratomileusis (LASIK) were evaluated. Pre-LASIK refraction and keratometry, post-LASIK topography, axial length (AL), IOL type and power, and 1-month postphacoemulsification refraction were recorded spherical equivalent after phacoemulsification (SE(postphaco)). Measured corneal power was adjusted using published and validated methods for postmyopic and posthyperopic LASIK. For each eye, and using SE(postphaco), different DK-IOL formulas were used to calculate the corresponding IOL power, the outcome measure, which was compared with the implanted IOL. DK-Holladay 1 yielded the highest Pearson correlation coefficient (PCC), 0.955 for myopes and 0.943 for high myopes (AL>26 mm). Mean error (ME) and mean absolute error (MAE) for myopes for DK Sanders-Retzlaff-Kraff theoretical formula [DK-SRK/T] were 0.44±0.84 D and 0.75±0.61 D for DK-SRK/T compared with -0.04±0.67 D and 0.52±0.40 D for DK-Holladay 1 (P<0.001 and P=0.016, respectively), and 0.03±0.88 and 0.64±0.58 for DK-Hoffer Q. For high myopes, ME and MAE were 0.75±0.81 D and 0.84±0.69 D for DK-SRK/T, and -0.05±0.74 D (P<0.0001) and 0.57±0.45 D (P=0.019) for DK-Holladay 1. About 29% of DK-SRK/T eyes with large AL had MAE>1.5 D, compared with 0% for DK-Holladay 1 and 14% for DK-Hoffer-Q. Eyes with previous hyperopic LASIK faired similarly for all formulas, with similar PCCs, and only 8% in each category with MAE>1.5 D. DK-SRK/T overestimates IOL power in eyes with large AL, especially with concomitant steep pre-lasik keratometry. Among third-generation formulas, DK-Holladay 1 seems more accurate to use in postmyopic LASIK eyes.

Modified double-K method for intraocular lens power calculation after excimer laser corneal refractive surgery

To propose the new anterior-posterior method (A-P method) that does not require historical data to calculate intraocular lens (IOL) power after laser in situ keratomileusis (LASIK) and to compare the accuracy of the method with other IOL formulas after LASIK. Keio University Hospital, Tokyo, Japan. Case series. Eyes having phacoemulsification and IOL implantation after myopic LASIK were analyzed retrospectively. The A-P method is a modification of the double-K method using the SRK/T formula in which the estimated pre-LASIK keratometry (K) power calculated from the post-LASIK posterior sagittal power in the 6.0 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 accuracy of the A-P method was compared with that of other formulas that do not require preoperative data and with formulas that require preoperative data. The median values of the arithmetic and absolute prediction errors using the A-P method were 0.16 diopter (D) and 0.54 D, respectively. The prediction errors using the A-P method were within ± 0.50 D in 46.4% of eyes and within ± 1.00 D in 75.0%. The percentage of eyes within ± 1.00 D of the prediction errors with the A-P method was highest with the no-history methods. The A-P method may be a good option for calculating IOL power in eyes having cataract surgery after LASIK when preoperative LASIK data are unavailable.