Lowest Median Absolute Error Research Articles

Efficacy of corneal curvature on the accuracy of 8 intraocular lens power calculation formulas in 302 highly myopic eyes.

To investigate the effect of corneal curvature (K) on the accuracy of 8 intraocular lens formulas in highly myopic eyes. Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China. Retrospective consecutive case series. 302 eyes (302 patients) were analyzed in subgroups based on the K value. The mean refractive error, mean absolute error (MAE), median absolute error (MedAE), root-mean-square absolute prediction error (RMSAE) and proportions of eyes within ±0.25 diopter (D), ±0.50 D, ±0.75 D, ±1.00 D were statistical analyzed. Emmetropia Verifying Optical (EVO) 2.0, Kane, and Radial Basis Function (RBF) 3.0 had the lower MAE (≤0.28) and RMSAE (≤0.348) and highest percentage of eyes within ±0.50 D (≥83.58%) in the flat (K ≤ 43 D) and steep K (K > 45 D) groups. Hoffer QST had the lowest MedAE (0.19), RMSAE (0.351) and the highest percentage of eyes within ±0.50 D (82.98%) in the normal K group (43 < K ≤ 45 D). When axial length (AL) ≤28 mm, all formulas showed close RMSAE values (0.322 to 0.373) in flat K group. When AL >28 mm, RBF 3.0 achieved the lowest MAE (≤0.24), MedAE (≤0.17) and RMSAE (≤0.337) across all subgroups. EVO 2.0, Kane, and RBF 3.0 were the most accurate in highly myopic eyes with a flat or steep K. Hoffer QST is recommended for long eyes with normal K values. RBF 3.0 showed the highest accuracy when AL >28 mm, independent of corneal curvature.

The accuracy of intraocular lens power calculation formulas based on artificial intelligence in highly myopic eyes: a systematic review and network meta-analysis.

To systematically compare and rank the accuracy of AI-based intraocular lens (IOL) power calculation formulas and traditional IOL formulas in highly myopic eyes. We screened PubMed, Web of Science, Embase, and Cochrane Library databases for studies published from inception to April 2023. The following outcome data were collected: mean absolute error (MAE), percentage of eyes with a refractive prediction error (PE) within ±0.25, ±0.50, and ±1.00 diopters (D), and median absolute error (MedAE). The network meta-analysis was conducted by R 4.3.0 and STATA 17.0. Twelve studies involving 2,430 adult myopic eyes (with axial lengths >26.0 mm) that underwent uncomplicated cataract surgery with mono-focal IOL implantation were included. The network meta-analysis of 21 formulas showed that the top three AI-based formulas, as per the surface under the cumulative ranking curve (SUCRA) values, were XGBoost, Hill-RBF, and Kane. The three formulas had the lowest MedAE and were more accurate than traditional vergence formulas, such as SRK/T, Holladay 1, Holladay 2, Haigis, and Hoffer Q regarding MAE, percentage of eyes with PE within ±0.25, ±0.50, and ±1.00 D. The top AI-based formulas for calculating IOL power in highly myopic eyes were XGBoost, Hill-RBF, and Kane. They were significantly more accurate than traditional vergence formulas and ranked better than formulas with Wang-Koch AL modifications or newer generations of formulas such as Barrett and Olsen. https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42022335969.

Visual Outcomes of Cataract Surgery in Patients With Keratoconus Using Toric and Non-toric Lenses

To compare the accuracy and outcomes of different intraocular lens (IOL) power calculation formulas in eyes with keratoconus undergoing cataract surgery with toric and non-toric IOLs. This was a consecutive retrospective case series study including patients from the Cornea Service at the Department of Ophthalmology and Visual Sciences at the University of British Columbia, Vancouver, Canada, from 2000 to 2020. Keratoconus was diagnosed based on corneal topography and clinician opinion. Patients who underwent topography-guided photorefractive keratectomy, intracorneal ring segments implantation, or corneal transplant were excluded. The manifest spherical equivalent, prediction errors, and median absolute errors were calculated. Descriptive statistics were expressed as mean ± standard deviation. There were 160 eyes from 101 patients; 136 eyes received non-toric lenses and 24 eyes received toric lenses. Most patients had mild disease (< 48.00 diopters [D]) when stratified by steep keratometry values. Patients with severe disease (> 53.00 D) were significantly more hyperopic following surgery (P < .05). The Barrett Universal II (0.26 D, inter-quartile range [IQR] = 0.4), Holladay 2 (0.31, IQR = 1.2), and SRK/T (0.42, IQR = 0.86) formulas had the lowest median absolute error. The postoperative prediction error following toric lens insertion was not significantly different than following non-toric lens insertion, and the mean absolute astigmatism was significantly reduced with toric lenses. The Barrett Universal II, Holladay 2, and SRK/T were the most accurate IOL power calculation formulas in patients with keratoconus undergoing cataract surgery. Hyperopic surprise was increased in severe keratoconus. Toric IOLs may be considered in patients with mild keratoconus. [J Refract Surg. 2023;39(5):319-325.].

Flapless and Conjunctiva-Sparing Technique for Transscleral Fixation of Intraocular Lens to Correct Refractive Errors in Eyes without Adequate Capsular Support.

To evaluate refractive outcomes, intraocular lens (IOL) power calculation, and IOL position following a novel conjunctiva-sparing transscleral fixation technique. Forty-one eyes of 40 patients managed with a flapless transscleral-sutured technique were included. Preoperative and postoperative refractive errors (spherical equivalents, SE) were compared. IOL position was assessed on the Scheimpflug images. IOL power was calculated by SRK/T, Holladay 1, and Hoffer Q formulas. The mean age was 57.39 ± 14.83 years (range: 26 to 79 years), and the mean follow-up was 7.46 ± 6.42 months (range: 1 to 24 months). Surgical indications were aphakia (n = 14), subluxated lenses (n = 3), and IOL dislocation (n = 24). The SE was 4.50 ± 6.38 diopter (D) (range: -3.75 to 13.75 D) preoperatively and -1.68 ± 1.57 D (range: -5.50 to 1.13 D) postoperatively (P < 0.001). The mean tilt angle and decentration were 2.90° ± 1.93° (range: 0.39° to 9.10°) and 0.23 ± 0.19 mm (range: 0.02 to 0.94 mm) vertically, and 1.75° ± 1.41° (range: 0.24° to 7.65°) and 0.18 ± 0.19 mm (range: 0.02 to 1.06 mm) horizontally, which were clinically insignificant. All three IOL formulas produced myopic errors (range: -0.29 to -0.50 D). The SRK/T had the lowest median absolute error (0.55 D), followed by the Holladay 1 (0.70 D) and the Hoffer Q (0.74 D). The three formulas had the same percentage of prediction errors (PEs) within ±0.5 D (43.48%), while the Hoffer Q had the highest percentage of PEs within ±1.0 D (82.61%). The present technique can serve as an alternative approach for transscleral IOL fixation and refractive correction in eyes with compromised capsular support, ensuring the stability of IOLs and reasonable IOL power calculation accuracy.

Autorefraction as an Objective Method to Evaluate Accuracy of Intraocular Lens Calculation Formulas.

To compare the spherical equivalent (SE) and astigmatic prediction error between subjective refraction (SUBref) and autorefraction (AUTOref) after cataract surgery to determine whether the latter is useful as an objective method to compare the accuracy of different methods of intraocular lens (IOL) power calculation. Postoperative refraction was examined using two techniques: SUBref and AUTOref. The results of these two techniques were compared. Predicted postoperative refraction for spherical outcome was calculated with the Barrett Universal II (BUII), Haigis, Holladay I, SRK/T, Hoffer Q, and BUII with measured posterior corneal astigmatism (MPCA) formulas. Predicted postoperative refraction for astigmatic outcome was calculated with the Barrett Toric calculator, vergence-based toric calculator using the Holladay 1 formula for effective lens position, and Barrett Toric calculator MPCA formulas. Formula accuracy and ranking were compared between the two methods of refraction. Data were obtained from 219 eyes of 155 patients. Statistically significant differences were detected between SUBref and AUTOref for SE, J0, and J45 (P < .001). The spherical outcome formula analysis demonstrated no significant differences, whereas the predicted cylinder power analysis demonstrated significant differences within individual formulas between SUBref and AUTOref measures. The lowest median absolute error and the highest percentage of eyes achieving their refractive target for both SUBref and AUTOref were achieved with the BUII formula and the Barrett Toric calculator. AUTOref is a useful method with adequate accuracy to determine spherical and astigmatic outcome and equally or more effective in being able to discriminate between spherical outcome formulas. The AUTOref method can allow valuable studies to be conducted in less-than-optimal environments and provides the ability to compare studies without the confounding factors of SUBref. [J Refract Surg. 2022;38(9):580-586.].

Intraocular lens power calculation with ray tracing based on AS-OCT and adjusted axial length after myopic excimer laser surgery.

To report the results of intraocular lens (IOL) power calculation by ray tracing in eyes with previous myopic excimer laser surgery. G.B. Bietti Foundation I.R.C.C.S., Rome, Italy. Retrospective interventional case series. A series of consecutive patients undergoing phacoemulsification and IOL implantation after myopic excimer laser was investigated. IOL power was calculated using ray-tracing software available on the anterior segment optical coherence tomographer MS-39. Axial length (AL) was measured by optical biometry, and 4 values were investigated: (1) that from the printout, (2) the modified Wang/Koch formula, and (3) the polynomial equation for the Holladay 1 and (4) for the Holladay 2 formulas. The mean prediction error (PE), median absolute error (MedAE), and percentage of eyes with a PE within ±0.50 diopters (D) were reported. The study enrolled 39 eyes. Entering the original AL into ray tracing led to a mean hyperopic PE (+0.56 ±0.54 D), whereas with the Wang/Koch formula, a mean myopic PE (-0.41 ±0.53 D) was obtained. The Holladay 1 and 2 polynomial equations lead to the lowest PEs (-0.10 ±0.49 D and +0.08 ±0.49 D, respectively), lowest MedAE (0.37 D and 0.25 D), and highest percentages of eyes with a PE within ±0.50 D (71.79% and 76.92%). Calculations based on the Holladay 2 polynomial equation showed a statistically significant difference compared with other methods used (including Barrett-True K formula), with the only exception of the Holladay 1 polynomial equation. IOL power was accurately calculated by ray tracing with adjusted AL according to the Holladay 2 polynomial equation.

Intraoperative aberrometry compared to preoperative Barrett True-K formula for intraocular lens power selection in eyes with prior refractive surgery.

To compare the predictive refractive accuracy of intraoperative aberrometry (ORA) to the preoperative Barrett True-K formula in the calculation of intraocular lens (IOL) power in eyes with prior refractive surgery undergoing cataract surgery at the Loma Linda University Eye Institute, Loma Linda, California, USA. We conducted a retrospective chart review of patients with a history of post-myopic or hyperopic LASIK/PRK who underwent uncomplicated cataract surgery between October 2016 and March 2020. Pre-operative measurements were performed utilizing the Barrett True-K formula. Intraoperative aberrometry (ORA) was used for aphakic refraction and IOL power calculation during surgery. Predictive refractive accuracy of the two methods was compared based on the difference between achieved and intended target spherical equivalent. A total of 97 eyes (69 patients) were included in the study. Of these, 81 eyes (83.5%) had previous myopic LASIK/PRK and 16 eyes (16.5%) had previous hyperopic LASIK/PRK. Median (MedAE)/mean (MAE) absolute prediction errors for preoperative as compared to intraoperative methods were 0.49 D/0.58 D compared to 0.42 D/0.51 D, respectively (P = 0.001/0.002). Over all, ORA led to a statistically significant lower median and mean absolute error compared to the Barrett True-K formula in post-refractive eyes. Percentage of eyes within ± 1.00 D of intended target refraction as predicted by the preoperative versus the intraoperative method was 82.3% and 89.6%, respectively (P = 0.04). Although ORA led to a statistically significant lower median absolute error compared to the Barrett True-K formula, the two methods are clinically comparable in predictive refractive accuracy in patients with prior refractive surgery.

Accuracy of intraocular lens power formulas for eyes with scleral-sutured intraocular lenses in congenital ectopia lentis

To compare the accuracy of intraocular lens (IOL) power calculation formulas in eyes with congenital ectopia lentis (CEL) that underwent scleral-fixated IOL implantation. Zhongshan Ophthalmic Center, Guangzhou, China. Retrospective consecutive case-series study. 158 eyes from 158 patients diagnosed from December 12, 2017, to November 16, 2020, with CEL and undergoing a lensectomy and scleral fixation of a Rayner 920H or 970C model IOL were retrospectively reviewed. The prediction errors (PEs) of the spherical equivalent of 8 formulas, Barrett Universal II (BUII), Emmetropia Verifying Optical (EVO), Haigis, Hoffer Q, Holladay 1, Kane, Hill-RBF 3.0, and SRK/T, were compared. For CEL patients with scleral-sutured IOL, all 8 formulas yielded myopic PEs without constant optimization. After such optimization, the performance of each formula ranked by median absolute error (MedAE) from the lowest to highest in diopter (D) was as follows: SRK/T (0.47), EVO (0.48), Kane (0.52), BUII (0.53), Hoffer Q (0.58), Holladay 1 (0.59), Haigis (0.61), and Hill-RBF 3.0 (0.62) formulas. The EVO and SRK/T formulas had the highest prediction accuracy concerning the percentage of cases within ±0.50 D and ±1.00 D range of PE in eyes that experienced scleral-sutured IOL surgery, respectively. All formulas before constant optimization produced myopic PEs. After optimization, the SRK/T and EVO formulas had the lowest MedAE and the highest percentage of PE in the range within ±0.50 D for CEL patients with scleral-sutured IOL implantations.

Factors affecting prediction error after cataract surgery with implantation of various multifocal IOLs in patients with previous refractive laser surgery.

BackgroundThis study aimed to compare the clinical outcomes of implantation of various multifocal intraocular lenses (mIOLs) and the prediction accuracy of two intraocular lens (IOL) power calculation formulas for eyes that underwent previous corneal refractive surgery.MethodsFour types of mIOLs [TECNIS Symfony (Group I), AcrySof IQ PanOptix (Group II), LENTIS Mplus (Group III), and TECNIS ZLB00 (Group IV)] were used and the IOL power was calculated with the two no-history methods, Shammas-PL and Barrett True-K. Visual acuity and refractive outcomes including manifest refraction, prediction error (PE), absolute error (AE), and median absolute error (MedAE) were evaluated at three months after the cataract surgery.ResultsFor all groups the Barrett True-K formula produced a narrower range of PEs and lower MedAE than Shammas-PL. Eyes of lower predictive accuracy (group B, AE >0.5D) showed weak uncorrected distance visual acuity resulting from myopic refractive error and target refraction when compared to that of higher predictive accuracy (group A, AE ≤0.5 D).ConclusionsTargeting emmetropia using the Barrett True-K, which considers both anterior and posterior corneal curvature is recommended in patients undergoing mIOL implantation with prior corneal refractive surgery. Additionally, history of prior large amount of laser ablation seems to be an important factor related to low predictive accuracy.

Refractive outcomes of second-eye adjustment methods on intraocular lens power calculation in second eye.

To investigate the refractive outcomes of second-eye adjustment (SEA) methods in different intraocular lens (IOL) power calculation formulas for second eye following bilateral sequential cataract surgery. This retrospective consecutive case-series study included 234 eyes from 234 patients who underwent bilateral sequential phacoemulsification and implantation of enVista MX60 in a hospital setting. Postoperative refraction outcomes calculated by standard formulas (SRK/T and Barrett Universal II, BUII) with SEA method were compared with those calculated by an artificial intelligence-based IOL power calculation formula (PEARL DGS) under second eye enhancement (SEE) method. The median absolute error (MedAE), mean absolute error (MAE) and percentage prediction errors (PE) of eyes within ±0.25 diopters (D), ±0.50 D, ±0.75 D and ± 1.00 D were determined. Overall, the improvement in MedAE after SEA was significant for PEARL DGS (p < 0.01), SRK/T (p < 0.001) and BUII (p=0.031), which increased from 74.36, 71.37, and 77.78% to 83.33, 80.34, and 79.49% of eyes within a PE of ±0.50 D, respectively. For first eyes with a medium axial length (22-26 mm), PEARL DGS with SEE had the lowest MedAE (0.21 D). For a first-eye MAE over 0.50 D, SEA method led to significant improvement in the second eye (p < 0.01). Interocular axis length differences exceeding 0.3 mm were associated with weaker effects using SEA in the studied formulas (p > 0.05). Either SEA method with SRK/T and BUII formulas or second-eye enhancement method based on the PEARL DGS formula can improve postoperative refractive outcomes in second eye.

Comparison of IOL Power Calculation Formulas for a Trifocal IOL in Eyes With High Myopia.

To analyze the results of new intraocular lens (IOL) formulas (Emmetropia Verifying Optical [EVO], Kane, Olsen, and Barrett Universal II), traditional formulas (Haigis and SRK/T), and modified Wang-Koch axial length adjustment formulas with the SRK/T and Holladay 1 (SRK/Tmodified-W/K and H1modified-W/K) in Chinese patients with long eyes. In this retrospective case series, patients with an axial length of 26 mm or greater having uneventful femtosecond laser-assisted cataract surgery with one trifocal IOL model were enrolled. The actual postoperative spherical equivalent of the manifest refraction was compared with the formula-predicted refraction based on the implanted IOL power. A subgroup analysis was performed based on the axial length. A total of 113 eyes was enrolled. Using User Group for Laser Interference Biometry constants, the modified Wang-Koch formulas had the lowest percentage of eyes with hyperopic outcomes. The Barrett Universal II, Olsen, Kane, and EVO 2.0 formulas produced a statistically lower median absolute error than the SRK/Tmodified-W/K and SRK/T formulas (P < .05). The Barrett Universal II formula produced higher percentages of eyes within ±0.50 diopters (D) of the prediction error than the SRK/T formula (P < .05). In eyes with axial lengths of less than 28 mm, there were no significant differences in the prediction accuracy of the eight formulas. In eyes with axial lengths of 28 mm or greater, the new IOL formulas yielded the lowest median absolute error, followed by the H1modified-W/K and Haigis formulas. The SRK/Tmodified-W/K formula had the highest mean absolute error and the lowest percentages of eyes within ±0.25 and ±0.50 D of endpoint. The traditional formulas yielded the highest risk of refractive surprise. All formulas achieved good results in eyes with axial lengths of less than 28 mm with trifocal IOL implanted. The newer formulas tend to produce better outcomes for eyes with high myopia. The SRK/Tmodified-W/K formula provided improved accuracy only in eyes with axial lengths of 30 mm or greater. [J Refract Surg. 2021;37(8):538-544.].

VRF-G, a New Intraocular Lens Power Calculation Formula: A 13-Formulas Comparison Study.

PurposeTo compare the accuracy of a newly developed intraocular lens (IOL) power formula (VRF-G) with twelve existing formulas (Barret Universal II, EVO 2.0, Haigis, Hill-RBF 2.0, Hoffer Q, Holladay 1, Kane, Næeser 2, PEARL-DGS, SRK/T, T2 and VRF).MethodsRetrospective case series including 828 patients having uncomplicated cataract surgery with the implantation of a single IOL model (SN60WF). Using optimised constants, refraction prediction error of each formula was calculated for each eye. Subgroup analysis was performed based on the axial length (short ≤22.0mm; medium >22.0mm to <26.0mm; long ≥26.0mm). Main outcomes included mean prediction error (ME) mean (MAE) and median absolute error (MedAE), in diopters (D), and the percentage of eyes within ±0.25D, ±0.50D, ±0.75D and ±1.00D.ResultsFormulas absolute errors were statistically different among them (p<0.001), with Kane having the lowest MAE of all formulas, followed by EVO 2.0 and VRF-G, which had the lowest MedAE. The Kane formula had the highest percentage of eyes within ±0.25D (47.0%) and ±1.00D (97.7%) and the VRF-G formula had the highest percentage of eyes within ±0.50D (79.5%). For all AL subgroups, Kane, EVO 2.0 and VRF-G formulas had the most accurate performances (lowest MAE).ConclusionNew generation formulas may help us in achieving better refractive results, lowering the variance in accuracy in extreme eyes – Kane, EVO 2.0 and VRF-G formulas are promising candidates to fulfil that goal.

Accuracy of common IOL power formulas in 611 eyes based on axial length and corneal power ranges

AimsTo provide clinical guidance on the use of intraocular lens (IOL) power calculation formulas according to the biometric parameters.Methods611 eyes that underwent cataract surgery were retrospectively analysed in subgroups according...

Accuracy of Artificial Intelligence Formulas and Axial Length Adjustments for Highly Myopic Eyes

To compare the accuracy of artificial intelligence formulas (Kane formula and Radial Basis Function [RBF] 2.0) and other formulas, including the original and modified Wang-Koch (MWK) adjustment formulas for Holladay 1 (H1-MWK) and SRK/T (SRK/T-WK and SRK/T-MWK), the Barrett Universal II (BUII), the emmetropia-verifying optical (EVO), and the Haigis equation in highly myopic eyes. Retrospective consecutive case-series study. A total of 370 eyes with an axial length (AL) ≥26.0mm of 370 patients were enrolled, and subgroup analyses was performed based on ALs. The median absolute error (MedAE), the percentages of eyes with hyperopic outcome and within ±0.25 diopters (D), ±0.50 D, and ±1.00 D of prediction error were determined. Overall, the Kane equation had the lowest MedAE (0.26 D), followed by H1-WK (0.27 D) and H1-MWK (0.28 D). There were no significant differences in MedAE among the Kane equation, the RBF 2.0, the BUII, the H1-MWK, and the H1-WK, whereas the Kane equation had a significantly lower MedAE than EVO (P < .001), SRK/T-MWK (P= .001), SRK/T-WK (P= .006), and Haigis (P < .001). In extremely myopic eyes with an AL ≥30.0mm (n= 115), the Kane equation had a significantly lower MedAE than the RBF 2.0 (P= .001), the EVO (P= .019), the BUII (P= .013), and the Haigis method (P= .005), whereas no significant differences were found among the Kane, H1-MWK, and H1-WK equations. The Kane equation was comparable to RBF 2.0, BUII, H1-MWK, and H1-WK in highly myopic eyes and was better than RBF 2.0 and BUII in extremely myopic eyes. The Kane, H1-MWK, and H1-WK methods were equally accurate in eyes with high to extreme myopia.

Accuracy of eight intraocular lens power calculation formulas for segmented multifocal intraocular lens.

To evaluate the accuracy of eight different intraocular lens (IOL) power calculation formulas for a segmented multifocal IOL. A total of 53 eyes of 41 adult cataract patients who underwent phacoemulsification and implantation with the SBL-3 segmented multifocal IOL between January 1, 2017 and January 31, 2019 were included in this retrospective study. Preoperative biometry measurements were obtained using an IOL Master. Manifest refraction was performed at least 4wk postoperatively. Accuracy of the eight formulas [Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Hill-RBF 2.0, Hoffer Q, Holladay 1, Kane, and SRK/T] was analyzed. Using current lens constants, all formulas exhibited errors of slight myopic shift in refractive prediction. The Barrett Universal II formula had a significantly lower median absolute error (MedAE) than did Holladay 1 (P=0.02), Kane (P=0.001) and Hill-RBF 2.0 (P<0.001) formulas. The Haigis formula had a lower MedAE value than did the Hill-RBF 2.0 formula (P=0.005). Differences in MedAE values among SRK/T, EVO and Hoffer Q formulas were not significant. After optimizing lens constants, the MedAE values of all formulas were reduced; significant changes were noted for EVO (P=0.022), Haigis (P=0.048), Hill-RBF 2.0 (P=0.014), Holladay 1 (P=0.045) and Kane (P=0.022) formulas. All formulas performed equally well after optimization of lens constants (P=0.203). All eight formulas tend to result in a myopic shift when using current lens constants. Optimized lens constants improve the accuracy of these formulas among adult Chinese patients.

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.].

Prediction of refractive outcomes with toric intraocular lens implantation

To evaluate and compare the accuracy of different methods to measure and predict postoperative astigmatism with toric intraocular lens (IOL) implantation. Ein-Tal Ophthalmology Center, Tel-Aviv, Israel. Retrospective case series. Postoperative corneal astigmatism was measured with 3 devices (IOLMaster 500; optical low-coherence reflectometry [OLCR]-based Lenstar LS 900; Atlas topographer) and compared with the manifest astigmatic refractive outcome in patients with toric IOLs. The error in the predicted residual astigmatism was calculated by vector analysis according to the measurement and calculation method used to predict the required toric IOL cylinder power. The centroid errors in predicted residual astigmatism were against the rule with the Alcon and Holladay toric calculators (0.53 to 0.56 diopter [D]), were lower with the Baylor nomogram (0.21 to 0.26 D), and were lowest for the Barrett toric calculator (0.01 to 0.16 D) (P <.001). The Barrett toric calculator had the lowest median absolute error in predicted residual astigmatism (0.35 to 0.54 D, all devices) compared with the Alcon and Holladay toric calculators with or without the Baylor nomogram (P <.021). The Barrett toric calculator and the OLCR device achieved the most accurate results; 75.0% and 97.1% of eyes were within ±0.50 D and ±0.75 D of the predicted residual astigmatism, respectively. Prediction of astigmatic outcomes with toric IOLs can be improved with appropriate measuring devices and methods to establish the required toric IOL power.

Riparian zone influence on stream water dissolved organic carbon concentrations at the Swedish integrated monitoring sites.

Short-term variability in stream water dissolved organic carbon (DOC) concentrations is controlled by hydrology, climate and atmospheric deposition. Using the Riparian flow-concentration Integration Model (RIM), we evaluated factors controlling stream water DOC in the Swedish Integrated Monitoring (IM) catchments by separating out hydrological effects on stream DOC dynamics. Model residuals were correlated with climate and deposition-related drivers. DOC was most strongly correlated to water flow in the northern catchment (Gammtratten). The southern Aneboda and Kindla catchments had pronounced seasonal DOC signals, which correlated weakly to flow. DOC concentrations at Gårdsjön increased, potentially in response to declining acid deposition. Soil temperature correlated strongly with model residuals at all sites. Incorporating soil temperature in RIM improved model performance substantially (20-62% lower median absolute error). According to the simulations, the RIM conceptualization of riparian processes explains between 36% (Kindla) and 61% (Aneboda) of the DOC dynamics at the IM sites.