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Purpose To investigate the influence of anterior chamber depth (ACD) on the accuracy of the Kane, EVO 2.0, Barrett Universal II (BU II), Olsen, SRK/T, and Haigis formulas in patients with elongated eyes. Design Retrospective case series study. Methods A total of 106 patients (106 eyes) diagnosed with high myopia (axial length ≥26 mm) were enrolled and divided into 3 subgroups according to preoperative ACD. Mean refractive error (ME), mean absolute refractive error (MAE), median absolute refractive error (MedAE), and proportions of eyes within ±0.25 D, ±0.50 D, ±0.75 D, and ±1.00 D were calculated. Results In all patients, the MedAE was lowest for the Kane formula (0.28 D), followed by the BU II (0.34 D). In the shallow ACD subgroup, EVO 2.0 formula produced the lowest MedAE (0.22 D), and the highest proportion of eyes within ±0.25 D (58%); the BU II (0.23 D, 50%) and Kane (0.25 D, 50%) formulas produced similar proportions. In the deep ACD group, the MedAEs of the Haigis and SRK/T formulas (0.68 D and 0.50 D, respectively) were significantly higher than those of the EVO 2.0 (0.37 D), Kane (0.30 D), BU II (0.43 D), and Olsen (0.34 D) formulas (P Conclusions Overall, the Kane and EVO 2.0 formulas had the highest accuracy. EVO 2.0 and BU II formulas are recommended for patients with shallow ACD; the Kane formula is recommended for patients with deep ACD (especially patients with extremely elongated eyes). The SRK/T and Haigis formulas should be avoided as much as possible.

Purpose This study aimed to analyze biometry values cutoffs for the choice of the best intraocular lens power calculation formula for AcrySof IQ Vivity intraocular lens. Methods The study was designed as interventional case series with 3 months of follow-up. Intraocular lens power calculation formulas included Barrett Universal II and SRK/T. The first was adopted for the intraocular lens power choice. The quantitative analysis focused on the identification of specific biometric cutoffs considering axial length, anterior chamber depth, and corneal powers. We included only the dominant eye in the statistical analysis. Results One hundred and eight eyes of 54 patients (23 males; mean age 62 ± 5 years) with no ocular diseases were included. Best-corrected visual acuity improved from 0.3 ± 0.2 to 0.0 ± 0.0 logMAR. All the eyes reached spectacles-free far and intermediate visions; a spherical addition of + 1.0D was necessary to adjust near vision. We identified significant quantitative cutoffs based on axial length and anterior chamber depth. Barrett Universal II resulted the best formula for eyes disclosing an axial length >25 mm, whereas SRK/T turned out to be the best choice for the eyes characterized by an anterior chamber depth Conclusions Axial length and anterior chamber depth influence the choice of Barrett Universal II and SRK/T formulas. Quantitative biometric cutoffs may be useful to discriminate the best formula to be adopted.

PURPOSE Intraocular lens (IOL) power calculation in eyes with keratoconus typically results in hyperopic postoperative refractive error. The purpose of this study was to investigate the visual and refractive outcomes in patients with keratoconus having cataract surgery with a toric IOL and compare IOL power calculation accuracy of conventional formulas and keratoconus-specific formulas. SETTING Ein-Tal Eye Center, Tel-Aviv, Israel. DESIGN Retrospective case-series study. METHODS Postoperative visual acuity and manifest refraction were examined. The error in predicted refraction and IOL power calculation accuracy within a range of 0.50 to 2.00 diopters (D) were compared between different IOL calculating formulas. RESULTS 32 eyes with keratoconus were included. Visual acuity improved in all cases, and subjective astigmatism decreased from -2.95 ± 2.10 D to -0.95 ± 0.80 D (P < .001). The mean absolute errors were as follows: Barrett True-K formula for keratoconus with measured or predicted posterior corneal power, 0.34 D; Barrett Universal II formula, 0.64 D; Kane formula, 0.69 D; Kane formula for keratoconus, 0.49 D; SRK/T formula, 0.56 D; Haigis formula, 0.72 D; Holladay 1 formula, 0.71 D, and Hoffer Q formula, 0.87 D. Barrett True-K formula with measured posterior corneal power, SRK/T formula, and Kane formula for keratoconus resulted in a prediction error within ±0.50 D of 87.5%, 59.4%, and 53.1%, respectively. CONCLUSIONS Cataract removal with a toric IOL significantly improves visual acuity and decreases astigmatism in keratoconic eyes with a topographic central relatively regular astigmatic component. Keratoconus-specific formulas resulted in lower mean error in predicted refraction compared with conventional calculating formulas. Using the posterior corneal power within the Barrett True-K formula for keratoconus improved IOL power prediction accuracy.

PURPOSE: To compare the accuracy of the Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Kane, and SRK/T formulas for intraocular lens power calculation in patients with high axial myopia. METHODS: In this retrospective study, 175 eyes (175 patients) that underwent uneventful cataract surgery were enrolled. According to the axial length (AL), the eyes were divided into long AL (26 ⩽ AL < 28 mm), super long AL (28 ⩽ AL < 30 mm), and extremely long AL (⩾ 30 mm). The mean absolute prediction errors (MAE) 3 months postoperatively and the percentage of eyes within different prediction error were compared, followed by subgroup analysis. RESULTS: The MAE and percentage of eyes within ±0.50 diopters (D) of the five formulas were as follows: Barrett Universal II (0.342, 74.9%), EVO 2.0 (0.314, 82.3%), Haigis (0.336, 74.9%), Kane (0.318, 78.9%), and SRK/T (0.398, 69.7%) ( P = .552 and .071, respectively). Although no significant difference was found among the five formulas in the super and extremely long AL groups ( P = .792 and .227, respectively), the EVO 2.0 formula achieved the highest accuracy (88.9%, 72 of 81) in the long AL group ( P = .049). Moreover, the accuracy of the EVO 2.0 and Haigis formulas was stable, regardless of AL. The SRK/T formula showed a negative trend in the long and super long AL groups, whereas the Barrett Universal II, Kane, and SRK/T formulas showed positive trends in the extremely long AL group. CONCLUSIONS: Overall, the EVO 2.0 and Kane formulas achieved better results in patients with high axial myopia, whereas the other three formulas showed slightly poor outcomes. [ J Refract Surg . 2021;37(11):754–758.]

It was almost 40 years ago when one of the authors (K.J.H.) published an organized system to quantify the accuracy of intraocular lens (IOL) power calculation formulas, methods, and instruments. At the behest of the editor of the American Journal of Ophthalmology, the IOL Power Club (along with a statistician) published an editorial in 2015 modernizing and quantifying the proper protocols for these studies. Over the past decade, so many new optical biometers, formulas, and methods (whose accuracies have yet to be completely tested) have been introduced that we were asked to modernize and update these guidelines yet again to help others design and report correctly the results of clinical studies on IOL power calculation and biometry for 2020. We evaluated guidelines to enroll patients, including visual acuity minimums, exclusion of bilateral eyes, sample size issues, demographics (age, gender, and ethnicity), and whether such studies should not be performed using the same data that were used to develop the formula being tested. We showed the absolute need for constant optimization, which formulas should be tested for comparison, refraction measurement (testing distance), as well as the analysis of the prediction error (median and mean absolute errors; standard deviation; range of errors; percentage of eyes with a prediction within ±0.25 diopter [D], ±0.50 D, ±0.75 D, and ±1.00 D; and interquartile displays) and statistical methods of analyses. We present methods of ranking formula accuracy, including the new Haigis IOL Formula Performance Index. We also point out the issues of who programmed the formulas being tested, that all formulas used in the study must be referenced, and the software version number of all instruments used in the study should be stated clearly. The definition of anterior chamber depth should be stated as measured from the corneal epithelium to the lens. We hope that these recommendations will help researchers to improve the validity and accuracy of their studies with the ultimate goal to improve the accuracy of IOL power calculation.

There is no enough knowledge about the accuracy of intraocular lens (IOL) power calculation formulas in steep corneas. This study may be the first one that compares the accuracy of the SRK II formula with Holladay1, Hoffer Q and Haigis formulas in steep corneas. We reported a case of a 60-year-old female, with a cataract in the left eye and with a steep cornea. We used the modern formulas; Holladay1, Hoffer Q and Haigis. The result (+7.0D) was unexpected compared to the manifest refraction and to the IOL power calculated in the right eye using the same formulas which was (+17.0D). We implanted (+12.0D) Sensar 1-piece IOL depending on our clinical experience. The post-operative refraction was (+0.00/-1.75axis106). Postoperative, we used the patient data to find the best formula in this case. We found that the SRK II (A118) result was (+11.5D) and thus this formula was the most accurate in this case. Keywords:SRK II; Holladay1; Hoffer Q; Haigis https://www.raftpubs.com/irjo-ophthalmology/articles/irjo_raft1012.php

Background To evaluate the effects of pretreatment for dry eye disease (DED) on the accuracy of intraocular lens (IOL) power calculation. Methods Patients who underwent uneventful cataract surgery were included in the study. IOL power was determined using the SRK/T and Barrett Universal II (Barrett) formulas. The patients were divided into non-pretreatment and pretreatment groups, and those in the pretreatment group were treated with topical 0.5% loteprednol etabonate and 0.05% cyclosporin A for 2 weeks prior to cataract surgery. Ocular biometry was performed in all groups within 2 days before surgery. The mean prediction error, mean absolute error (MAE), and proportions of refractive surprise were compared between the non-pretreatment and pretreatment groups at 1 month postoperatively. Refractive surprise was defined as MAE ≥ 0.75D. Results In a total of 105 patients, 52 (52 eyes) were in the non-pretreatment group and 53 (53 eyes) in the pretreatment group. The MAE was 0.42 ± 0.33, 0.38 ± 0.34 (SRK/T, Barrett) and 0.23 ± 0.19, 0.24 ± 0.19 in the non-pretreatment and pretreatment groups, respectively (p p = 0.024/0.016]. Pretreatment of DED was related to a reduction in postoperative refractive surprise. [SRK/T/Barrett: OR = 0.18/0.17 (95% CI: 0.05–0.71/0.05–0.60), p = 0.014/0.006]. Conclusions The accuracy of IOL power prediction can be increased by actively treating DED prior to cataract surgery.

Objective: To compare optical biometry and A-scan for calculating intraocular lens power in patients with nuclear cataract at tertiary care eye hospital. Study Design: Cross sectional comparative study. Place and Duration of Study: Armed Forces Institute of Ophthalmology, Pak Emirates Military Hospital, Rawalpindi, from Jul to Dec 2018. Methodology: In this study 70 eyes of 70 patients planned for cataract surgery by phacoemulsification underwent both optical biometry with intraocular lens master and ultrasound biometry applanation by A scan after informed consent. Intraocular lens power calculated by these two methods of biometry was compared. Phacoemulsification surgery was performed through a 2.3 mm superior temporal clear corneal incision. All patients underwent in the bag implantation of the same intraocular lens type. Results: The mean age of the patients was 62.89 ± 6.69 years. A significant (p-value65 years. Conclusion: Optical biometry was found efficient and safe method for calculation of intraocular lens power. Optical biometry is noncontact method having very less chance of infection and suitable for most of the eye types.

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.

Purpose: We investigated the change in the absolute error according to the difference between anterior and total keratometry, to determine the criterion for the difference in keratometry, and to determine the indication for using total keratometry. Methods: Sagittal and total refractive power were measured with 2-, 3-, and 4-mm Pentacam® rings, and the absolute error of each was calculated in patients who underwent cataract surgery in our hospital. The correlation between the difference value the sagittal minus the total refractive power and each absolute error was analyzed by simple regression analysis. The analysis was performed by dividing the patients into two groups based on 0.6, which is the average of the difference between the sagittal and total refractive power for the 3-mm ring. Results: Sagittal power was larger than total refractive power for all rings and the absolute error obtained by applying the total refractive power was larger than the sagittal power for the 2- and 4-mm rings (p < 0.001). The simple regression analysis revealed that the absolute error using sagittal power was positively correlated with the difference between sagittal power and total refractive power. In the group with less than 0.6, the absolute error using the total refractive power of all rings was larger than the sagittal power (p < 0.001). In the group exceeding 0.6, the absolute error using the total refractive power was less than using the sagittal power for the 3 mm ring (p = 0.028). Conclusions: The greater the difference between sagittal and total refractive power, the greater the absolute error using sagittal power. Accuracy was higher in the group exceeding 0.6 after applying total refractive power measured at the 3 mm ring compared to sagittal power.

To evaluate the prediction accuracy of the intraocular lens (IOL) power calculation using adjusted corneal power according to the posterior/anterior corneal curvature radii ratio in the Haigis formula (Haigis-E) in patients with a history of prior myopic laser vision correction. Seventy eyes from 70 cataract patients who underwent cataract surgery and had a history of myopic laser vision correction were enrolled. The adjusted corneal power obtained with conventional keratometry (K) was calculated using the posterior/anterior corneal curvature radii ratio measured by a single Scheimpflug camera. In eyes longer than 25.0 mm, half of the Wang-Koch (WK) adjustment was applied. The median absolute error (MedAE) and the percentage of eyes that achieved a postoperative refractive prediction error within ± 0.50 diopters (D) based on the Haigis-E method was compared with those in the Shammas, Haigis-L, and Barrett True-K no-history methods. The MedAE predicted using the Haigis-E (0.33 D) was significantly smaller than that obtained using the Shammas (0.44 D), Haigis-L (0.43 D), and Barrett True-K (0.44 D) methods (P

Objective: To evaluate the effect of pterygium excision on intraocular lens (IOL) power and refraction. Methods: The present study was carried out on patients with combined cataract and pterygium excision (combined group) and pterygium surgery first and cataract surgery after one month (sequential group). Parameters such as mean keratometry (K) values, axial length, IOL power, and corneal astigmatism were compared pre and postoperatively in the combined and sequential groups. Results: 70 eyes of 70 patients were included in the present study. The mean age of the participants in the combined group was 70.46±10.12, whereas that in the sequential group was 68.68±11.22 (p=0.243). The mean horizontal length of the pterygium in the combined group was 2.64±0.17 mm and 2.57±0.17 mm in the sequential group. The mean postoperative K values (p=0.03) and IOL power (p=0.04) in the combined group were significantly higher than the preoperative values. The estimated postoperative refractive error in the combined group was -0.50±1.00 D and 0.25±0.5 D in the sequential group (p=0.04). On the other hand, the postoperative refraction in the sequential group was predictable. Corneal visibility was diminished on the nasal side in almost all the patients in the combined group as compared to the sequential group. Conclusion: The postoperative refraction errors were positively correlated with the length of pterygium in the combined group. The unpredictability of these errors recommends sequential surgery in cases with concurrent pterygium and cataract.

AimTo compare the preoperative biometric data and the refractive accuracy of cataract surgery among major surgical sites in a nationwide multicentre study.MethodsWe prospectively obtained the preoperative biometric data of 2143 eyes of 2143 consecutive patients undergoing standard cataract surgery at major 12 facilities and compared the preoperative biometry as well as the postoperative refractive accuracy among them.ResultsWe found significant differences in most preoperative variables, such as axial length (one-way analysis of variance, p=0.003), anterior chamber depth (pConclusionsRegional divergences of the preoperative biometry were not necessarily negligible, and the optimised intraocular lens power calculation formula was individually different among the 12 facilities. Our findings highlight the importance of individual optimisation of these formulas at each facility, especially in consideration of these biometric variations.Trial registration numberClinical Trial Registry; 000039976.

This study evaluated the accuracy of total keratometry (TK) and standard keratometry (K) for intraocular lens (IOL) power calculation in eyes treated with femtosecond laser-assisted cataract surgery. The retrospective study included a retrospective analysis of data from 62 patients (91 eyes) who underwent uneventful femtosecond laser-assisted cataract surgery with Artis PL E (Cristalens Industrie, Lannion, France) IOL implantation by a single surgeon between May 2020 and December 2020 in Severance Hospital, Seoul, South Korea. The new IOLMaster 700 biometry device (Carl Zeiss Meditec, Jena, Germany) was used to calculate TK and K. The mean absolute error (MAE), median absolute error (MedAE), and the percentages of eyes within prediction errors of ± 0.25 D, ± 0.50 D, and ± 1.00 D were calculated for all IOL formulas (SRK/T, Hoffer-Q, Haigis, Holladay 1, Holladay 2, and Barrett Universal II). There was strong agreement between K and TK (intraclass correlation coefficient = 0.99), with a mean difference of 0.04 D. For all formulas, MAE tended to be lower for TK than for K, and relatively lower MAE and MedAE values were observed for SRK/T and Holladay 1. Furthermore, for all formulas, a greater proportion of eyes fell within ± 0.25 D of the predicted postoperative spherical equivalent range in the TK group than in the K group. However, differences in MAEs, MedAEs, and percentages of eyes within the above prediction errors were not statistically significant. In conclusion, TK and K exhibit comparable performance for refractive prediction in eyes undergoing femtosecond laser-assisted cataract surgery.

Summary Purpose Descemet membrane endothelial keratoplasty (DMEK) combined with cataract extraction and intraocular lens insertion (new triple procedure) limits postoperative refractive errors. The objective of this study was to assess refractive accuracy after DMEK combined with cataract extraction and intraocular lens implantation. Setting Four university hospitals (Rouen, Paris, Reims, Grenoble). Design This retrospective multicenter study included patients with symptomatic corneal endothelial decompensation and cataract. Methods The primary outcome was the difference between the target spherical equivalent and postoperative refraction at months 2 and 6. Secondary outcomes were visual acuity, keratometry, pachymetry and endothelial cell density. Results A total of 130 eyes of 111 patients (mean age 66.2 years) were included (94% with Fuchs’ endothelial dystrophy). For a mean refractive target set at −0.50 (±0.57) D, the mean (95% CI) refractive error was hyperopia of +0.49 (0.314; 0.664) D at 2 months and +0.46 (0.299; 0.619) D at 6 months. Best corrected distance visual acuity was improved in all patients: from 0.49 (±0.3) logMAR to 0.14 (±0.14) logMAR at 2 months and 0.05 (±0.1) logMAR at 6 months. Mean corneal thickness decreased from 621.6 (±37.6) μm to 515.2 (±42.6) μm at 2 months and 539.0 (±39.0) μm at 6 months. Conclusions Good refractive accuracy was obtained after the new triple procedure with DMEK. Hyperopic shift is common after triple procedures, and its persistence should be evaluated in future studies in order to anticipate a change in its value to optimize intraocular lens power calculation.

Purpose To review the literature to evaluate the outcomes of intraocular lens (IOL) power calculation in eyes with a history of myopic LASIK or photorefractive keratectomy (PRK). Methods Literature searches were conducted in the PubMed database in January 2020. Separate searches relevant to cataract surgery outcomes and corneal refractive surgery returned 1169 and 162 relevant citations, respectively, and the full text of 24 was reviewed. Eleven studies met the inclusion criteria for this assessment; all were assigned a level III rating of evidence by the panel methodologist. Results When automated keratometry was used with a theoretical formula designed for eyes without previous laser vision correction, the mean prediction error (MPE) was universally positive (hyperopic), the mean absolute errors (MAEs) and median absolute errors (MedAEs) were relatively high (0.72–1.9 diopters [D] and 0.65–1.73 D, respectively), and a low (8%–40%) proportion of eyes were within 0.5 D of target spherical equivalent (SE). Formulas developed specifically for this population requiring both prerefractive surgery keratometry and manifest refraction (i.e., clinical history, corneal bypass, and Feiz-Mannis) produced a proportion of eyes within 0.5 D of target SE between 26% and 44%. Formulas requiring only preoperative keratometry or no history at all had lower MAEs (0.42–0.94 D) and MedAEs (0.30–0.81 D) and higher (30%–68%) proportions within 0.5 D of target SE. Strategies that averaged several methods yielded the lowest reported MedAEs (0.31–0.35 D) and highest (66%–68%) proportions within 0.5 D of target SE. Even after using the best-known methods, refractive outcomes were less accurate in eyes that had previous excimer laser surgery for myopia compared with those that did not have it. Conclusions Calculation methods requiring both prerefractive surgery keratometry and manifest refraction are no longer considered the gold standard. Refractive outcomes of cataract surgery in eyes that had previous excimer laser surgery are less accurate than in eyes that did not. Patients should be advised of this refractive limitation when considering cataract surgery in the setting of previous corneal refractive surgery. Conclusions are limited by the small sample sizes and retrospective nature of nearly all existing literature in this domain.

Purpose: To assess the predictability of desired postoperative refractive outcomes using the SRK-II formula for intraocular lens (IOL) power calculation in children undergoing cataract surgery in eyes with a previous pars plana vitrectomy (PPV). Methods: In this retrospective study, 68 eyes of 66 children who underwent cataract surgery and IOL implantation in eyes that had previous vitrectomy between January 2008 and December 2017 were included. Data were collected on preoperative and postoperative characteristics. The Mann-Whitney test, Kruskal-Wallis test, and multinominal logistic regression were used for comparing the results. Results: Absolute prediction error (APE) in the cohort was 1.29 ± 1.13. Desirable refractive outcome with insignificant prediction error of less than 0.50 diopters (D) was found in approximately one-third of the children. Patients were further subdivided by magnitude of APE as ≥ 0.50 to ≤ 1.00 D and > 1.00 D. Age at the time of surgery, axial length, mean keratometry, silicone oil removal, IOL position, scleral buckle, and corneal suture did not affect APE and there was no significant difference between the groups ( P > .05). Conclusions: The mean APE of the SRK-II formula for IOL power calculation in pediatric eyes that had vitrectomy is comparable to that reported in the literature for routine pediatric cataract surgeries. Factors such as age, axial length, corneal power, IOL position (bag/sulcus), scleral buckle, corneal suture, and silicone oil removal done prior to surgery or along with cataract surgery did not affect the APE. [ J Pediatr Ophthalmol Strabismus . 2021;58(2):126–131.]

PURPOSE To evaluate and compare the predictability of intraocular lens (IOL) power calculation after small-incision lenticule extraction (SMILE) for myopia and myopic astigmatism. SETTING Department of Ophthalmology, Philipps University of Marburg, Marburg, Germany. DESIGN Retrospective comparative case series. METHODS Preoperative evaluation included optical biometry using IOLMaster 500 and corneal tomography using Pentacam HR. The corneal tomography measurements were repeated at 3 months postoperatively. The change of spherical equivalent due to SMILE was calculated by the manifest refraction at corneal plane (SMILE-Dif). A theoretical model, involving the virtual implantation of the same IOL before and after SMILE, was used, and the IOL power calculations were performed using ray tracing (OKULIX, version 9.06) and third- (Hoffer Q, Holladay 1, and SRK/T) and fourth-generation (Haigis-L and Haigis) formulas. The difference between the IOL-induced refractive error at corneal plane before and after SMILE (IOL-Dif) was compared with SMILE-Dif. The prediction error (PE) was calculated as the difference between SMILE-Dif-IOL-Dif. RESULTS The study included 204 eyes that underwent SMILE. The PE with ray tracing was -0.06 ± 0.40 diopter (D); Haigis-L, -0.39 ± 0.62 D; Haigis, 0.70 ± 0.48 D; Hoffer Q, 0.84 ± 0.47 D; Holladay 1, 1.21 ± 0.51 D; and SRK/T, 1.46 ± 0.54 D. The PE with ray tracing was significantly smaller compared with that of all formulas (P ≤ .001). The PE variance with ray tracing was σ2 = 0.159, being significantly more homogenous compared with that of all formulas (P ≤ .011, F ≥ 6.549). Ray tracing resulted in an absolute PE of 0.5 D or lesser in 81.9% of the cases, followed by Haigis-L (53.4%), Haigis (35.3%), Hoffer Q (25.5%), Holladay 1 (6.4%), and SRK/T (2.9%) formulas. CONCLUSIONS Ray tracing was the most accurate approach for IOL power calculation after myopic SMILE.

PURPOSE: To comparatively evaluate the accuracy of newer intraocular lens (IOL) calculation formulas and common third-generation formulas after Wang-Koch adjustment in the prediction of postoperative refraction in highly myopic eyes. METHODS: This was a retrospective study including eyes with high myopia that had uncomplicated cataract surgery with implantation of an AcrySof MA60MA IOL (power range: −5.00 to +5.00 diopters [D]) (Alcon Laboratories, Inc). All patients underwent optical biometry (Carl Zeiss IOLMaster 500 and IOLMaster 700, and Allegro Biograph) and the postoperative spherical equivalent for the implanted IOL was estimated using SRK/T, Holladay 1 (both Wang-Koch adjusted), Haigis, Barrett Universal II, Kane, Ladas, and Hill-RBF v2.0 formulas. Outcomes included the median absolute prediction error (MedAE) and the proportion of eyes within ±0.25, ±0.50, and ±1.00 D of the preoperative prediction. RESULTS: Eighty-two eyes with a mean axial length of 30.89 ± 1.85 mm were included. The MedAE in ascending order was Hill-RBF v2.0 0.31 D, Kane 0.33 D, Barrett 0.36 D, Holladay I wk 0.37 D, SRK/T wk 0.37 D, Holladay I wk 0.43 D, Haigis ULIB 0.54 D, and Ladas 0.61 D. The formula with the lowest MedAE (Hill-RBF v2.0) yielded a prediction error within ±0.25, ±0.50, and ±1.00 D in 43.1%, 70.6%, and 94.1% of cases, respectively. CONCLUSIONS: Recent formulas such as Barrett Universal II, Kane, and Hill-RBF v2.0 and Wang-Koch adjusted formulas perform well in this subset of patients with high myopia. The Hill-RBF v2.0 formula had the lowest MedAE and highest proportion of eyes within ±0.25, ±0.50, and ±1.00 D of the predicted target. [ J Refract Surg . 2021;37(3):207–211.]

Background: The effectiveness of cataract surgery depends on preoperative biometric data, including the axial length (AL), keratometric value (K), anterior chamber depth (ACD), and the accuracy of the intraocular lens power (IOLp) calculation. Five generations of IOLp calculation formulas have been developed. This review summarizes these formulas and focuses on the characteristics, advantages, and disadvantages of each. Moreover, it compares the results of several formulas used in patients with specific characteristics. Methods: The authors searched PubMed and Google Scholar, using keyword combinations including IOLp, formulas, AL, ACD, K, and diopters (D). Two hundred recent articles that referred to IOLp calculation formulas and their effectiveness when used preoperatively in cataract surgery were retrieved and analyzed. Results: Each generation has advantages and disadvantages for individual patients, and the selection of the most appropriate IOL differs due to patients’ different ALs. The shorter or longer the eye is, the less accurate some formulas become. Formulas such as SRK-T, Holladay, SRK-II, Hoffer, and Binkhorst II seem to have comparable efficacy. However, studies have indicated that Hoffer is superior for short eyes. In contrast, SRK/T appears to be slightly more superior for long eyes. The fifth-generation formulas also appear to be very promising. Conclusions: Based on the available literature, there is no gold standard as yet that can be used for all patients. Instead, each patient should be managed individually depending on their particular eye characteristics.

Purpose: To assess the accuracy of the intraocular lens (IOL) power calculation based on three methods using artificial intelligence (AI) and one formula using no AI. Methods: During cataract surgery on 114 eyes, one type of IOL was implanted, calculated with the Hill-RBF 2.0 method. The theoretical postoperative refractions were calculated using the Kane and the Pearl-DGS methods and a vergence based formula (Barrett Universal II, BUII). The differences between the manifest and objective postoperative refractions and the predicted refractions were calculated. The percentage of eyes within ±0.5 D and ±1.0 D prediction error (PE), the mean, and the median absolute errors (MAE and MedAE) were also determined. Results: The mean age of the patients was 69.48 years; the axial length was between 21.19 and 25.39 mm. The number of eyes within ±0.5/±1.0 D PE was 96/108 (84.21%/94.73%) using the Hill-RBF 2.0 method, 92/107 (80.70%/93.85%) with the Kane method, 91/107 (79.82%/93.85%) with the Pearl-DGS method, and 91/106 (79.82%/92.98%) with the BUII formula, using subjective refraction. With objective refractometric data, PEs were within ±0.5 D in 88 (77.19%), 83 (72.80%), 82 (71.92%), and 80 (70.17%) cases (Hill-RBF, Kane, Pearl-DGS, BUII, respectively). MAE and MedAE were also best with the Hill-RBF 2.0 method (0.3 D; 0.18 D). Conclusion: Better accuracy of PE might be obtained by the Hill-RBF 2.0 method compared with BUII. The Kane and Pearl-DGS methods showed similar accuracy when compared with BUII.

Objective To assess the precision of Barrett Universal II, SRK-T, and Haigis formulas in high myopic eyes for the estimation of intraocular lens power, using optical biometry. Patients and methods This is an interventional prospective study that included 34 eyes with an axial length more than or equal to 26 mm, who underwent uneventful phacoemulsification. One month after the surgery, we recorded the postoperative refraction. Refractive prediction error (RPE), median absolute error (Med AE), and proportion of eyes with postoperative myopic and hyperopic outcomes were compared. Results The lowest mean RPE (−0.11±0.90 D), Med AE (0.15 D), and proportion of eyes with hyperopic outcomes (44.1%) were reported with the Barrett Universal II formula. They were all statistically lower than the results of SKR/T and Haigis formulas (mean RPE 0.16±0.99 and 0.31±0.98 D, respectively; Med AE 0.47 and 0.40 D, respectively; and percentage of hyperopic outcome 70.6 and 76.5%, respectively). Conclusion We concluded that the lowest mean RPE, median AE, and the lowest percentage of hyperopic outcome were reported with the Barrett Universal II formula.

Purpose: To evaluate the accuracy of 12 intraocular lens (IOL) power formulas; Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Hill-Radial Basis Function (RBF), Hoffer Q, Holladay I, Kane, Ladas Super Formula, Olsen Lenstar, Panacea, Pearl-DGS, Sanders-Retzlaff-Kraff/theoretical (SRK/T). In addition, an analysis of the efficacy as a function of the axial length was performed. Methods: About 171 from 93 patients: 68 male eyes and 103 female eyes. Twelve IOL power formula calculations were studied with one IOL platform (trifocal hydrophilic IOL, FineVision Micro F), one biometer (Lenstar LS 900), one topographer (CSO Sirius Topographer), one surgeon, and one optometrist. Optimization were determined to be zeroed mean refractive prediction error. Mean error (ME), mean absolute error (MAE), median absolute error (MedAE) and refractive accuracy within ±1.00 D was calculated. Axial length was split in short and medium eyes. Results: One hundred and seventy eyes were included. Formulas were ranked by percentage within ±0.50 diopters and MAE (D). Among all eyes, Olsen 86.55% (0.273 D) and Barrett Universal II 86.55% (0.285D). For short eyes (Conclusion: Olsen and Barrett formula obtained excellent accuracy for overall eyes. Kane and Olsen formula obtained the best results in short eyes. For medium axial length Barrett formula achieved the best accuracy results.

Aims and Objectives: To compare the accuracy of ultrasound A scan biometry and IOL master (PCI) biometry in intraocular power calculation, by doing a comparative study of difference in biometry by conventional methods and optical biometry (IOL master). Materials and Methods: Place of study: Aravind Eye Hospital, India. Design of Study: Prospective, non randomised, clinical study. Study Group and Duration: The study involves patients who underwent cataract surgeries at Aravind Eye Hospital, Tirunelveli during the specified time period. The IOL power and predicted refractive outcome were calculated for every patient by both the methods, A scan ultrasound Biometry IOL master (Partial Coherence interferometry) Inclusion Criteria: Only those patients in whom it was possible to secure a reliable IOL master reading (on the basis of good SNR), were included. Results: In a 12 month period, 337 eyes were consecutively enrolled in the study. Both ultrasound A scan and partial coherence interferometry was performed and IOL power implanted as per the IOL master. Inclusion criterion and exclusion criterion used as mentioned. The difference in between the final and predicted refraction is compared for both the groups. The overall Mean absolute error was 0.402 ± 0.407 with the ultrasound A scan & 0.388 ± 0.406 for the IOL master, with the probability value (p-value) 0.3802. The mean numerical error (the difference between the refractive outcome and the predicted spherical equivalent) is -0.226 ± 0.526 (min -2.66 & max 2.06) for the ultrasound scan group and -0.217 ± 0.518 (min -2.41 & max 2.10) for the IOL master group, with the probability value (p-value) being 0.514. We got a comparative result in our study, though not significant, but it is more in favour of IOL master (PCI) as per the mean absolute error and mean numerical error calculations. When analysing the Mean Axial Length readings, the findings were almost similar, with an insignificant p-value. Keywo

Aim — to compare intraocular lens (IOL) power calculation before and after different types glaucoma procedures. Material and methods. Into the study, 115 patients were included, divided into 3 groups: group 1 — patients, in whom sinustrabeculectomy was performed ( n = 86); group 2 — patients with implanted Ex-PRESS shunt ( n = 19), group 3 — patients after Ahmed glaucoma valve implantation ( n = 10). For each patient before surgery optical biometry (IOL-Master 500) was performed and IOL power calculation using Barrett Universal II Formula (target refraction — emmetropia). Baseline data were compared with corresponding examinations results obtained in 6 months after glaucoma procedure, to evaluate its effect on main biometric parameters of the eye and the IOL calculation accuracy. Results. Despite significant changes of optical and anatomic indices, mean values of target refraction before and after glaucoma surgery did not differ significantly: 0.00 ± 0.03 versus 0.03 ± 0.52 D ( p = 0.628), 0.00 ± 0.1 versus 0.19 ± 0.61 D ( p = 0.173), –0.04 ± 0.08 versus 0.11 ± 0.42 D ( p = 0.269) for groups, respectively. However, there was a pronounced trend to the increase of target refraction data scattering. Conclusion. Glaucoma procedures cause changes of biometrical parameters of the eye, which leads to decrease in accuracy of IOL calculation. Consequently, when choosing intraocular lens, it is recommended to use measurement results obtained after glaucoma surgery. Keywords: intraocular lens; IOL power calculation; glaucoma; sinustrabeculectomy; Ex-PRESS shunt; Ahmed glaucoma valve; biometry; phacoemulsification; axial length; anterior chamber depth; keratometry.

Purpose To 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, Naeeser 2, PEARL-DGS, SRK/T, T2 and VRF). Methods Retrospective 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

SIGNIFICANCE This review summarizes the main factors of refractive error after silicone oil removal combined with cataract surgery.The post-operative refractive results of silicone oil removal combined with cataract surgery are closely related to the patient's future vision quality. This report summarizes the factors that influence the difference between the actual post-operative refractive power and the pre-operatively predicted refractive power after silicone oil removal combined with cataract surgery, including axial length, anterior chamber depth, silicone oil, commonly used tools for measuring intraocular lens power, and intraocular lens power calculation formulas, among others. The aim of the report is to assist clinical and scientific research on the elimination of refractive error after silicone oil removal combined with cataract surgery.

PurposeThe present retrospective study was designed to test the hypothesis that the postoperative posterior to preoperative anterior corneal curvature radii (PPPA) ratio in eyes with Fuch’s dystrophy undergoing Descemet membrane endothelial keratoplasty (DMEK) is significantly different to the posterior to anterior corneal curvature radii (PA) ratio in virgin eyes and therefore renders conventional keratometry (K) and the corneal power derived by it invalid for intraocular lens (IOL) power calculation.MethodsMeasurement of corneal parameters was performed using Scheimpflug imaging (Pentacam HR, Oculus, Germany). In 125 eyes with Fuch’s dystrophy undergoing DMEK, a fictitious keratometer index was calculated based on the PPPA ratio. The preoperative and postoperative keratometer indices and PA ratios were also determined. Results were compared to those obtained in a control group consisting of 125 eyes without corneal pathologies. Calculated mean ratios and keratometer indices were then used to convert the anterior corneal radius in each eye before DMEK to postoperative posterior and total corneal power. To assess the most appropriate ratio and keratometer index, predicted and measured powers were compared using Bland-Altman plots.ResultsThe PPPA ratio determined in eyes with Fuch’s dystrophy undergoing DMEK was significantly different (P P ∆ = − 0.14D ± 0.30) and overestimation of total corneal power (∆ = − 0.45D ± 1.08). The lowest prediction errors were found using the geometric mean PPPA ratio (0.806) and corresponding keratometer index (1.3273) to predict the postoperative posterior (∆ = − 0.01 ± 0.30) and total corneal powers (∆ = − 0.32D ± 1.08).ConclusionsCorneal power estimation using conventional K for IOL power calculation is invalid in eyes with Fuch’s dystrophy undergoing DMEK. To avoid an overestimation of corneal power and minimize the risk of a postoperative hyperopic shift, conventional K for IOL power calculation should be adjusted in eyes with Fuch’s dystrophy undergoing cataract surgery combined with DMEK. The fictitious PPPA ratio and keratometer index may guide further IOL power calculation methods to achieve this.

Purpose To assess the accuracy of the Kane formula for intraocualr lens (IOL) power calculation in comparison with established formulas in the elderly population. Setting Shiley Eye Institute, University of California San Diego, USA. Design Retrospective cohort. Methods Retrospective data from 90 patients (90 eyes) aged 75 years or older who underwent uneventful cataract surgery with SN60WF intraocular lens (IOL) implantation were evaluated. The first operated eyes of patients with final corrected distance visual acuity 20/40 or better and axial length 22 to 26 mm were included. Prediction errors were calculated for Barrett Universal (BU) II, Haigis, Hoffer Q, Holladay 1, Kane, and SRK/T formulas. A subgroup analysis based on age (75-84 and ≥85 years old) was performed. Results Use of both BUII and Kane formulas resulted in the highest percentage of eyes with prediction errors within ±0.50 diopters (D) (72% each) and significantly higher than Hoffer Q, Holladay 1, and SRK/T (P = .001). Rates of predictability within ±0.25 D and ±1.00 D were 31% to 38% and 87% to 92%, respectively, with no significant differences between formulas. No statistically significant difference was seen between formulas in the median absolute error. These tendencies remained consistent in both age groups when analyzed separately. Subgroup analysis showed better predictability of all formulas in the younger age group. Conclusions To the authors' knowledge, this is the first study evaluating the Kane formula exclusively in the elderly population. The Kane formula was found to be of equal accuracy to the BUII and superior to the Hoffer Q, Holladay 1, and SRK/T formulas. Very elderly patients might have reduced refractive precision using all formulas.

To evaluate the features of the axial length-to-corneal radius (AL/CR) ratio in Japanese patients with cataracts and to determine the accuracy of intraocular lens (IOL) power calculation formulas according to the AL/CR features and the axial length (AL).Retrospective observational case series.Setting was a clinical practice. Patient population was a total of 1,135 eyes (1,135 patients) with cataracts. Observation procedures included measurement of the AL and corenal radius (CR) by optical biometry and evaluation of the refractive outcomes by using the SRK/T, Holladay 1, Hoffer Q, Haigis, and Barrett Universal II formulas. Main outcome measurements were the features of the AL/CR ratio and the accuracy of IOL power calculations based on the AL/CR ratio and the AL.The mean AL/CR ratio was 3.15 ± 0.19. Significant weak negative correlations were observed between the spherical equivalent (SE) and AL (r = -0.7489; P.001) and between the SE and AL/CR ratio (r = -0.8069; P.001); no correlation was found between the SE and CR (r = 0.0208, P = .483). For medium ALs and high AL/CR ratios, the SRK/T formula performed less accurately. For long ALs and high AL/CR ratios, the Holladay 1 and Hoffer Q formulas performed less accurately. The Barrett Universal II formula performed well across a range of ALs and AL/CR ratios.The AL/CR ratio explained the total variation in the SE better than the AL alone. Surgeons should pay attention to the selection of IOL power calculation formulas in eyes with high AL/CR ratios.

PURPOSE: To evaluate the influencing factors on remaining astigmatism after implanting a toric intraocular lens (IOL) during cataract surgery. METHODS: This retrospective study included parameters that were considered to have an influence on toric IOL power calculation. Therefore, data from the literature and the authors' own data were used. This included axial eye length, anterior chamber depth, central corneal thickness, corneal radii (anterior and posterior), diurnal changes of the cornea, inter-device differences, rotational misalignment of the IOL, tilt and decentration of the IOL, pupil size, angle kappa, and surgically induced astigmatism. Ray-tracing and Gaussian error propagation analysis was performed to quantify the sources of error. RESULTS: In total, 4,949 eyes (4,365 eyes of 42 studies and 584 eyes of retrospectively analyzed study data) were included in the study and the difference vector between aimed and calculated remaining astigmatism was 0.81 diopters (D). The main source of error was the preoperative measurement of the cornea (27%), followed by IOL misalignment (14.4%) and IOL tilt (11.3%). Other factors, such as angle kappa (10.9%), pupil size (8.1%), surgically induced astigmatism (7.8%), anterior chamber depth (7.5%), axial eye length (7.5%), and decentration (5.6%), also contributed to the refractive astigmatic error. CONCLUSIONS: The main source of error in toric IOL power calculation is the preoperative corneal measurement followed by IOL misalignment and tilt. [ J Refract Surg . 2020;36(10):646–652.]

AIM: To evaluate the accuracy of eight different intraocular lens (IOL) power calculation formulas for a segmented multifocal IOL. METHODS: 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. RESULTS: 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

Background Fourth-generation formulas for intraocular lens power calculations, including the Barrett Universal II formula, the Olsen formula or the Holladay 2 formula, were thoroughly validated with optical biometry measurements. They precisely predict the effective lens position not only in normal eyes but also in eyes with unusual anatomy. However, in the setting of dense nuclear or posterior subcapsular cataracts, optical biometers fail to obtain accurate measurements and third-generation formulas, i.e. the Hoffer Q or the SRK/T, combined with ultrasound measurements are a method of choice. Considering that optical biometry was fine-tuned to immersion ultrasound, we hypothesize that fourth-generation formulas will yield precise intraocular lens power calculations with immersion ultrasound measurements. Methods We retrospectively analyzed 50 eyes of 50 patients who underwent uneventful cataract surgery. All patients had intraocular lens power calculated based on immersion ultrasound measurements. Refractive error predictions were compared between third-generation formulas and fourth-generation formulas. Results There were no statistically significant differences in the median absolute error between formulas. In the study, 86%, 88%, 86%, 84%, 88% and 80% of eyes were within 1 D of target refraction for the SRK/T, the Barrett II, the Hoffer Q, the Holladay 1, the Holladay 2 and the Olsen formula respectively. Conclusion Fourth-generation formulas combined with immersion ultrasound produced similar results to third-generation formulas. However, the percentage of eyes within 1 D of target refraction remains inferior to previously reported results for optical biometry measurements.

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.

Objectives To compare different methods in calculating the corneal radius (R) to be used in case of intraocular lens power calculations when it is immeasurable. Methods The right eyes of 1,960 patients were randomly divided into 2 equal groups. The first group of right eyes (group A) was divided in three groups according to the axial length (AL) (≤21.99 mm, between 22 and 24.99 mm, and ≥25 mm). In these groups, the correlation between the AL and the corneal radius (R) provided three different regression formulas. The second group of right eyes (group B) was used to test the following methods of estimating the R: the regression formulas determined from group A, formula from Logan et al., formula from Stenstrom, the mean R calculated from group A, and the fellow eye group B. A Student paired T test was used for the statistical evaluation. Results In case of AL≤21.99, the best results have been obtained with the fellow eye R, followed by either the regression formula or the mean R from group A (mean=0.00±0.09 mm, P=0.94, mean=0.05±0.21 mm, P=0.05, mean=0.05±0.22 mm, P=0.08, respectively). In case of AL between 22 and 24.99 mm, the best results have been obtained with the fellow eye R, followed by either the regression formula or the mean R from group A (mean=-0.01±0.09 mm, P=0.38, mean=0.01±0.21 mm, P=0.12, mean=0.01±0.24 mm, P=0.18, respectively). In case of AL≥25 mm, the best results have been obtained with the fellow eye R, followed by either the regression formula or the mean R from group A (mean=-0.003±0.08 mm, P=0.94 mean=-0.004±0.25 mm, P=0.85, mean=-0.004±0.25 mm, P=0.85, respectively). Conclusions The new calculated regression formulas seem to represent a reliable method to calculate the R when it is undetectable, as in case of corneal dystrophies.

Purpose The purpose of this study is to develop and assess the accuracy of a new intraocular lens (IOL) power calculation method based on machine learning techniques. Methods The following data were retrieved for 260 eyes of 260 patients undergoing cataract surgery: preoperative simulated keratometry, mean keratometry of posterior surface, axial length, anterior chamber depth, lens thickness, and white-to-white diameter; model and power of implanted IOL; and subjective refraction at 3 months post surgery. These data were used to train different machine learning models (k-Nearest Neighbor, Artificial Neural Networks, Support Vector Machine, Random Forest, etc). Implanted lens characteristics and biometric data were used as input to predict IOL power and refractive outcomes. For external validation, a dataset of 52 eyes was used. The accuracy of the trained models was compared with that of the power formulas Holladay 2, Haigis, Barrett Universal II, and Hill-RBF v2.0. Results The SD of the prediction error in order of lowest to highest was the new method (designated Karmona) (0.30), Haigis (0.36), Holladay 2 (0.38), Barrett Universal II (0.38), and Hill-RBF v2.0 (0.40). Using the Karmona method, 90.38% and 100% of eyes were within ±0.50 and ±1.00 D respectively. Conclusions The method proposed emerged as the most accurate to predict IOL power. Sin financiación 4.456 JCR (2021) Q1, 11/62 Ophthalmology 1.427 SJR (2021) Q1, 23/508 Arts and Humanities (miscellaneous) No data IDR 2021 UEM

With more than 1.5 million Small Incision Lenticule Extraction (SMILE) procedures having already been performed worldwide in an ageing population, intraocular lens (IOL) power calculation in post-SMILE eyes will inevitably become a common challenge for ophthalmologists. Since no refractive outcomes of cataract surgery following SMILE have been published, there is a lack of empirical data for optimizing IOL power calculation. Using the ray tracing as the standard of reference – a purely physical method that obviates the need for any empirical optimization - we analyzed the agreement of various IOL power calculation formulas derived from the American Society of Cataract and Refractive Surgeons (ASCRS) post-keratorefractive surgery online calculator. In our study of 88 post-SMILE eyes, the Masket formula showed the smallest mean prediction error [−0.36 ± 0.32 diopters (D)] and median absolute error (0.33D) and yielded the largest percentage of eyes within ±0.50D (70%) in reference to ray tracing. Non-inferior refractive prediction errors and ±0.50D accuracies were achieved by the Barrett True K, Barrett True K No History and the Potvin-Hill formula. Use of these formulas in conjunction with ray tracing is recommended until sufficient data for empirical optimization of IOL power calculation after SMILE is available.

IMPORTANCE There is no clear consensus on which intraocular lens (IOL) power calculation formula provides the best refractive prediction in the paediatric population. BACKGROUND To evaluate the predictability of desired postoperative refractive outcomes by using six IOL formulas in paediatric cataract cases. DESIGN Retrospective case series. PARTICIPANTS A total of 377 eyes in 377 paediatric patients (

A new method is developed and validated for intraocular lens (IOL) power calculation based on paraxial ray tracing of the postoperative IOL positions, which are obtained with the use of anterior segment optical coherence tomography. Of the 474 eyes studied, 137 and 337 were grouped into training and validation sets, respectively. The positions of the implanted IOLs of the training datasets were characterized with multiple linear regression analyses one month after the operations. A new regression formula was developed to predict the postoperative anterior chamber depth with the use of the stepwise analysis results. In the validation dataset, postoperative refractive values were calculated according to the paraxial ray tracing of the cornea and lens based on the assumption of finite structural thicknesses with separate surface curvatures. The predicted refraction error was calculated as the difference of the expected postoperative refraction from the spherical-equivalent objective refraction values. The percentage error (within ±0.50 diopters) of the new formula was 84.3%. This was not significantly correlated to the axial length or keratometry. The developed formula yielded excellent postoperative refraction predictions and could be applicable to eyes with abnormal proportions, such as steep or flat corneal curvatures and short and long axial lengths.

Introduction: This study aims to evaluate the accuracy of the measurement parameters of the new Verion Image Guided System compared with an established standard of care. Purpose: To compare the keratometry (K) and white-to-white (WTW) measurements obtained from the Lenstar Optical Biometer (LS) with those from the Verion Image-Guided System (VR) and their effect on intraocular lens (IOL) power calculation. Design: Prospective comparative case series. Materials and methods: Sixty patients going for cataract surgery had biometry measurements and IOL calculation with the LS. Axial length from LS was used together with K and WTW measurements from VR for IOL calculation as well. IOL selection was done using the Barrett Universal II formula targeting emmetropia. The prediction error (PE) within 0.25 D, 0.5 D, and 1 D of refractive target and the mean absolute error (MAE) were calculated for both the LS and VR. Results: Keratometry measurements and steep axis from the VR were closely correlated with the LS (Pearson correlation coefficient K1, r = 0.958; K2, r = 0.952; axis, r = 0.950). The WTW measurements were less so (WTW, r = 0.471). The MAE was 0.317 and 0.347 for LS and VR, respectively. PE within 0.25 D was 48.3% and 40%; within 0.5 D was 83.3% and 76.7%; and within 1 D was 98.3% and 96.7% for LS and VR, respectively. There was no statistically significant difference in MAE between the LS and VR (p = 0.74) Conclusion: Using the K and WTW measurements from the Verion Image-Guided System for IOL power calculation did provide comparable results with the Lenstar. The Lenstar had a higher proportion of eyes within 0.5 D of refractive target but the difference was not statistically significant.

There are an increasing number of people who have had refractive surgery now developing cataract. To compare the accuracy of different intraocular lens (IOL) power calculation formulas after laser refractive surgery (photorefractive keratectomy or laser in situ keratomileusis), a comprehensive literature search of PubMed and EMBASE was conducted to identify comparative cohort studies and case series comparing different formulas: Haigis-L, Shammas-PL, SRK/T, Holladay 1 and Hoffer Q. Seven cohort studies and three observational studies including 260 eyes were identified. There were significant differences when Hoffer Q formula compared with SRK/T, Holladay 1. Holladay 1 formula produced less prediction error than SRK/T formula in double-K method. Hoffer Q formula performed best among SRK/T and Holladay 1 formulas in total and single-K method. In eyes with previous data, it is recommended to choose double-K formula except SRK/T formula. In eyes with no previous data, Haigis-L formula is recommended if available, if the fourth formula is unavailable, single-k Hoffer Q is a good choice.

AIM: To evaluate the accuracy of three commonly used biometric formulae across different axial lengths (ALs) at one United States Veterans Affairs teaching hospital. METHODS: A retrospective chart review was conducted from November 2013 to May 2018. One eye of each patient who underwent cataract surgery with a monofocal intraocular lens (IOL) was included. The range of postoperative follow-up period was from 3wk to 4mo. The Holladay 2, Barrett Universal II, and Hill-Radial Basis Function (Hill-RBF) formulae were used to predict the postoperative refraction for all cataract surgeries. For each formula, we calculated the prediction errors [including mean absolute prediction error (MAE)] and the percentage of eyes within ±0.25 diopter (D) and ±0.5 D of predicted refraction. We performed subgroup analyses for short (AL25.0 mm). RESULTS: A total of 1131 patients were screened, and 909 met the inclusion criteria. Resident ophthalmologists were the primary surgeons in 710 (78.1%) cases. We found no statistically significant difference in predictive accuracy among the three formulae over the entire AL range or in the short, medium, and long eye subgroups. Across the entire AL range, the Hill-RBF formula resulted in the lowest MAE (0.384 D) and the highest percentage of eyes with postoperative refraction within ±0.25 D (42.7%) and ±0.5 D (75.5%) of predicted. All three formulae had the highest MAEs (>0.5 D) and lowest percentage within ±0.5 D of predicted refraction (

Purpose To compare the accuracy of Sirius ray tracing software with the Barrett Universal II formula for intraocular lens power prediction in virgin eyes. Methods Retrospective case series including 86 eyes that have undergone uneventful cataract surgery with SN60WF implantation. The median absolute error, mean prediction error, variance, and the percentage of eyes within ± 0.25 D, ± 0.50 D, ± 0.75 D, and ± 1.00 D of the prediction error in refraction were calculated. The correlation of prediction error with different baseline parameters was investigated. Results No differences were found between the median absolute error of the Barrett Universal II formula (0.226 D) and the ray tracing software with different intraocular lens centerings; apex (0.331 D), limbus (0.345 D), and pupil (0.342 D) ( p = 0.084). The variance, from lowest to highest, was the Barrett Universal II (0.144 D2), ray tracing-limbus (0.285 D2), ray tracing-pupil (0.285 D2), and ray tracing-apex (0.287 D2) ( p = 0.027). The Barrett Universal II formula showed a higher percentage of eyes within ± 0.25 D (56.98%), ± 0.50 D (82.56%), and ± 0.75 D (93.02%) compared to ray tracing software ( p Conclusion There is a trend of the Barrett Universal II formula to be more accurate than Sirius ray tracing software for intraocular lens power calculation in virgin eyes. This should be confirmed in future prospective comparative studies.

Purpose of review We review recent studies comparing intraocular lens (IOL) formulas with an emphasis on selection of the highest performing formulas based on patient axial length, age, and history of previous corneal refractive surgery. Recent findings The Barrett Universal II formula based on a theoretical model has consistently demonstrated high accuracy. The Olsen four-factor formula using ray tracing optics and the Hill-RBF calculator using artificial intelligence have also demonstrated good prediction results after being updated. Notably, the Kane formula, incorporating artificial intelligence, has overall shown the best performance for all axial lengths. Although newly developed and updated IOL formulas have improved refractive prediction in patients with short or long axial length eyes or prior history of corneal refractive surgery, these challenging cases still require special consideration. The Barrett True-K formula has shown accurate results regardless of preoperative data in eyes with previous myopic refractive surgery. Summary Advancements in optical biometry and IOL calculation formulas continue to improve refractive outcomes. The clinician can optimize refractive outcomes in the majority of patients with the use of formulas that have shown consistent results and accuracy in several large studies.

The major challenge these days in pediatric cataract surgery is not the technique of surgery or intraocular lens (IOL) used but the postoperative refractive error. Amblyopia occurring due to postoperative refractive error which the child has; destroys the benefit obtained by a near-perfect and timely surgery. Even if we settle the debate as to what should be the ideal postoperative target refraction, there is a postoperative surprise that is not explained by our conventional insights of an accurate power calculation in children. The role of IOL power calculation formulae in affecting the postoperative refractive error should not be underestimated. Therefore, which age-appropriate formula is to be used for children is unclear. This review is an update on major IOL power calculation formulas used in pediatric eyes. We have tried to define why we should not be using these formulas made for adult eyes and review the literature in this regard.

Daiki Sakai,1– 3 Yasuhiko Hirami,1,2 Makoto Nakamura,3 Yasuo Kurimoto1,2 1Department of Ophthalmology, Kobe City Eye Hospital, Kobe, Japan; 2Department of Ophthalmology, Kobe City Medical Center General Hospital, Kobe, Japan; 3Department of Surgery, Division of Ophthalmology, Kobe University Graduate School of Medicine, Kobe, JapanCorrespondence: Daiki SakaiDepartment of Ophthalmology, Kobe City Eye Hospital, 2-1-8 Minatojima Minamimachi, Chuo-ku, Kobe-shi, Hyogo, 650-0047, JapanTel +81-78-381-9876Fax +81-78-381-9910Email dsakai1027@gmail.comPurpose: To compare the accuracy of the intraocular lens (IOL) power calculation formulas for predicting the postoperative refraction in eyes with a target of emmetropia or intentional myopia.Patients and Methods: This is a retrospective study conducted at Kobe City Eye Hospital, Kobe, Japan. Fifty eyes of 50 patients with axial myopia who underwent uncomplicated phacoemulsification and single-type IOL implantation for a target of emmetropia (plano to − 0.5 D) or intentional myopia (− 2.0 D to − 3.0 D) were selected. Preoperative ocular biometry was performed using IOLMaster700 in all eyes. Refractive prediction errors of 6 IOL formulas integrated into IOLMaster700 were compared between eyes with a target of emmetropia and intentional myopia.Results: The mean numerical errors of SRK/T (Sanders, Retzlaff, and Kraft/theoretical), Holladay 1, Hoffer Q, and Holladay 2 significantly differed between the two groups (p < 0.001, p = 0.008, 0.02, and 0.007, respectively). The values for mean numerical errors in eyes with a target of intentional myopia were smaller, showing relatively myopic outcome, as compared with those in eyes with a target of emmetropia. In eyes with a target of emmetropia, the mean numerical errors of Holladay 1 (p < 0.001, 95% confidence interval [CI]: 0.32 to 0.63), Hoffer Q (p = 0.001, 95% CI: 0.12 to 0.42), and Barrett Universal II (p = 0.007, 95% CI: 0.06 to 0.35) were significantly different from zero (hyperopic trend). Furthermore, in eyes with a target of intentional myopia, the mean numerical error of SRK/T (p = 0.001, 95% CI: − 0.61 to − 0.17) and Holladay 2 (p = 0.023, 95% CI: − 0.43 to − 0.04) were significantly different from zero (myopic trend).Conclusion: In patients with axial myopia, some IOL formulas may show a myopic trend in the refractive outcome when targeting intentional myopia as compared to emmetropia.Keywords: cataract surgery, postoperative refraction, intentional myopia, axial myopia, IOLMaster700