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Purpose: To compare the biometric measurements obtained from the Pentacam AXL Wave, IOLMaster 700, and ANTERION and calculate the recommended intraocular lens power using the Barrett Formulae. Methods: This was a retrospective cross-sectional study of patients who underwent biometry using the Pentacam AXL Wave, IOLMaster 700, and ANTERION. Flat keratometry (K1), steep keratometry (K2), anterior chamber depth (ACD), and axial length (AL) from each device were measured and compared. These parameters were used to calculate the recommended IOL powers using the Barrett formula. Results: The study included 252 eyes of 153 patients. The IOLMaster had the highest acquisition rate among the two biometers. The Pentacam obtained the shortest mean AL, the IOLMaster measured the highest mean keratometry values, and the ANTERION measured the highest mean ACD. In terms of pairwise comparisons, keratometry and axial length were not significantly different between the Pentacam-IOLMaster and ANTERION-IOLMaster groups, while the rest of the pairwise comparisons were statistically significant. In nontoric and toric eyes, 35–45% of patients recommended the same sphere of IOL power. In another 30–40%, the Pentacam and ANTERION recommended an IOL power one step greater than that of the IOLMaster-derived data. 50% of the study population recommended the same toric-cylinder IOL power. Conclusions: The Pentacam AXL Wave, IOLMaster 700, and ANTERION can reliably provide data for IOL power calculations; however, these data are not interchangeable. In nontoric and toric eyes, 35–45% of cases recommended the same sphere IOL power, and in another 30–40%, the Pentacam and ANTERION recommended one-step higher IOL power than the IOLMaster-derived data. In targeting emmetropia, selecting the first plus IOL power is advisable when using the Pentacam and ANTERION to approximate the IOL power calculations recommended by the IOLMaster 700. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to investigate the influence of ocular biometry parameters on the predictive accuracy of 10 intraocular lens (IOL) power formulas in patients with high myopia (HM). Methods: We analyzed 202 eyes of 202 patients. The ocular biometry was determined preoperatively using an IOLMaster 700. The associations between the biometry parameters and the prediction error (PE) 1 month postoperatively were assessed. HM was defined as an axial length exceeding 26.50 mm. Results: In patients with HM (n = 108), the K6, Emmetropia Verifying Optical (EVO), Olsen, and Barrett Universal II (BUII) formulas had the lowest absolute PEs among the 10 formulas. The ocular biometry parameters were not associated with the PE of K6, EVO, Olsen, or BUII. A longer axial length in HM eyes was associated with myopic outcomes by Kane, Hoffer QST, and VRF and hyperopic outcomes by Holladay 2 and T2. Steeper keratometry, a deeper anterior chamber, and a thicker lens were associated with a hyperopic shift in HM eyes when using VRF, Kane, and Hoffer QST, respectively. In patients without HM (n = 94), there was no difference between the formulas in absolute PE. The significant associations between the biometry parameters and PE in patients with HM were not present in patients without HM. Conclusions: K6, EVO, Olsen, and BUII displayed high accuracy in HM eyes and were not influenced by preoperative biometry parameters. For the remaining formulas, the preoperative keratometry, anterior chamber depth, lens thickness, and axial length were possible error sources underlying an inaccurate IOL power prediction in patients with HM. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of the optional biometric parameters lens thickness (LT) and center corneal thickness (CCT) in the Kane formula on intraocular lens (IOL) power calculation. Methods: A cross-sectional study included consecutive cataract patients who received uncomplicated cataract surgery with IOL implantation from May to September 2022 were enrolled. The ocular biometric parameters were obtained using IOLMaster 700 and then inputted into online Kane formula calculator. The IOL power was calculated for targeting emmetropia and compared between groups: not omitting (NO) group, omitting LT and CCT (OLC) group, omitting LT (OL) group and omitting CCT (OC) group. Further, according to the axial length (AL), anterior chamber depth (ACD), and mean keratometry (Km), the eyes were divided into three subgroups, respectively. Results: 1005 eyes of 1005 consecutive patients were included. There was no significant difference in IOL power between NO group and OC group (P = 0.064), and the median absolute difference (MedAD) was 0.05D. The IOL power in NO group showed significant differences from OLC group and OL group respectively (P < 0.001), and both MedAD values were 0.18D. Among AL subgroups, MedAD ranged from 0.06D to 0.35D in short eyes. Among ACD subgroups, the above values ranged from 0.06D to 0.23D in shallow ACD subgroup. Among Km subgroups, these values ranged from 0.05D to 0.31D in steep Km subgroup. Conclusion: The optional biometric parameter CCT has no effect on the calculation results of the Kane formula, whereas the parameter LT has a great influence on the Kane formula results for the IOL power calculation in cataract patients with short AL, shallow ACD and steep Km. [ABSTRACT FROM AUTHOR]

One of the most common and successful ophthalmic procedures today is the removal of water from the eye and the implantation of a fake intraocular lens. One of the excess issues, notwithstanding, is the precise computation of intraocular lens power important for accomplishing the ideal postoperative refraction. Refractive result following phacoemulsification relies on exactness in different factors utilized in biometry procedure. In this study I have analyzed the intraocular lens power estimation by traditional applanation ultrasound, customary submersion ultrasound and halfway coherence laser interferometer For our tertiary instructional hub, where staff with varying degrees of involvement and mastery in biometry take estimates the context of computation of the intraocular lens that is needed prior to waterfall medical procedure, the review examined visual biometry values using applanation and inundation procedures. [ABSTRACT FROM AUTHOR]

Purpose: This study was conducted to evaluate the accuracy of intraoperative aberrometry (IA) in intraocular lens (IOL) power calculation and compare it with conventional IOL formulas.Methods: This was a prospective case series. Eyes with visually significant cataract and axial hyperopia (AL <22.0 mm) underwent IA-assisted phacoemulsification with posterior chamber IOL (Alcon AcrySof IQ). Postoperative spherical equivalent (SE) was compared with predicted SE to calculate the outcomes with different formulas (SRK/T, Hoffer Q, Haigis, Holladay 2, Barrett Universal Ⅱ and Hill-RBF). Accuracy of intraoperative aberrometer was compared with other formulas in terms of mean absolute prediction error (MAE), percentage of patients within 0.5 D and 1 D of their target, and percentage of patients going into hyperopic shift.Results: Sixty-five eyes (57 patients) were included. In terms of MAE, both Hoffer Q (MAE = 0.30) and IA (MAE = 0.32) were significantly better than Haigis, SRK/T, and Barrett Universal Ⅱ (P < 0.05). Outcomes within ±0.5 D of the target were maximum with Hoffer Q (80%), superior to IA (Hoffer Q > IA > Holladay 2 > Hill-RBF > Haigis > SRK/T > Barrett Universal Ⅱ). Hoffer Q resulted in minimum hyperopic shift (30.76%) followed by Hill-RBF (38.46%), Holladay 2 (38.46%), Haigis (43.07%), and then IA (46.15%), SRK/T (50.76%) and Barrett Universal Ⅱ (53.84%).Conclusion: IA was more effective (statistically significant) in predicting IOL power than Haigis, SRK/T, and Barrett Universal Ⅱ although it was equivalent to Hoffer Q. Hoffer Q was superior to all formulas in terms of percentage of patients within 0.5 D of their target refractions and percentage of patients going into hyperopic shift. [ABSTRACT FROM AUTHOR]

Background: Ocular magnification and aniseikonia after cataract surgery has been widely ignored in modern cataract surgery. The purpose of this study was to analyse ocular magnification and inter‐individual differences in a normal cataract population with a focus on monovision. Methods: From a large dataset containing biometric measurements (IOLMaster 700) of both eyes of 9734 patients prior to cataract surgery, eyes were indexed randomly as primary (P) and secondary (S). Intraocular lens power (IOLP) was derived for the HofferQ, Haigis and Castrop formulae for emmetropia for P and emmetropia or myopia (−0.5 to −2 dpt) for S to simulate monovision. Based on the pseudophakic eye model in addition to these formulae, ocular magnification was extracted using matrix algebra (refraction and translation matrices and a system matrix describing the optical property of the entire spectacle corrected or uncorrected eye). Results: With emmetropia for P and S the IOLP differences (S‐P) showed a standard deviation of 0.162/0.156/0.157 dpt and ocular magnification differences yielded a standard deviation of 0.0414/0.0405/0.0408 mm/mrad for the HofferQ/Haigis/Castrop setting. Simulating monovision, the myopic eye (S) showed a systematically smaller mean absolute spectacle corrected ocular magnification than the emmetropic eye (−0.0351/−0.0340/−0.0336, respectively, relative magnification around 2%). If myopia in the S eye remains uncorrected, the reduction of ocular magnification is much smaller (around 0.2–0.3%). Conclusion: Vergence formulae for IOLP calculation sometimes implicitly define a pseudophakic eye model which can be directly used to predict ocular magnification after cataract surgery. Despite a strong similarity of both eyes, ocular magnification does not fully match between eyes and the prediction of ocular magnification and aniseikonia might be relevant to avoid eikonic problems in the pseudophakic eye. [ABSTRACT FROM AUTHOR]

The best overall results with the sum-of-segments biometry were noted with the B II, BTAL, EVO, Hoffer QST, K6, Kane, Olsen, and PEARL-DGS formulas. Purpose: To analyze the accuracy of newer intraocular lens power formulas in long and short eyes measured using the sum-of-segments biometry. Setting: Private practice, Lynwood, California. Design: Retrospective observational study. Methods: 595 patients scheduled for cataract surgery had their eyes measured using the sum-of-segments biometry. The expected residual refractions were calculated using Barrett Universal II (B II), Barrett True Axial Length (BTAL), Emmetropia Verifying Optical (EVO), Hill-RBF, Hoffer QST, Holladay 2, Holladay 2-NLR, K6, Kane, Olsen, PEARL-DGS, T2, and VRF formulas and compared with the traditional Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. Results: In the 102 long eyes, all new formulas had a mean absolute error (MAE) equal or lower than the traditional formulas, ranging from 0.29 to 0.32 diopter (D). In the 78 short eyes, BTAL, EVO, Hoffer QST, K6, Olsen, and PEARL-DGS formulas had the lowest MAE (0.33 D, 0.33 D, 0.31 D, 0.36 D, 0.32 D, and 0.32 D, respectively), whereas all traditional formulas exceeded 0.36 D. Conclusions: All new formulas performed equal or better than the traditional formulas with the sum-of-segments biometry. The best overall results in the short and long eyes as well as in the very short and very long eyes were noted with the BTAL, EVO, Hoffer QST, K6, Olsen, and PEARL-DGS formulas, closely followed by the B II and Kane formulas. [ABSTRACT FROM AUTHOR]

Purpose: To compare the efficacy of Kane formula with Sanders Retzlaff Kraff/Theoretical (SRK/T) and Barrett Universal II in predicting intraocular lens (IOL) power in Indian eyes.Methods: This retrospective study conducted in a tertiary care eye hospital. Data from patients having uneventful cataract surgery with Tecnis ZCB00 IOL implantation were obtained from Lenstar and electronic medical records. Eyes were divided into subgroups based on axial length (AL) as short (<22.0 mm), medium (22-24 mm), and long (>24 mm). The predicted refractive outcome for each patient was calculated after optimizing the lens constant. Prediction error was calculated by subtracting the predicted spherical equivalent from achieved spherical equivalent 1 week post-surgery. The mean absolute error (MAE) and median absolute error (MedAE) and percentage of eyes within 0.25, 0.5, 1, and 2 D were calculated for each formula. Friedman test, Cochrane Q test were used for statistical analysis.Results: Out of the 350 eyes included in the study, we found that without lens constant optimization, Barrett formula performed better than SRK/T and Kane (P < 0.0001). Over the entire range of axial lengths, Kane formula performed slightly inferior compared to Barrett and SRK-T, both of which performed equally well (P = 0.006). On subgroup analysis, Kane formula performed inferiorly for medium eyes as compared to the other two. No significant differences were noted between the formulae for short and long eyes.Conclusion: Kane formula did not outperform Barrett Universal II and SRK/T in Indian eyes. [ABSTRACT FROM AUTHOR]

This review article attempts to evaluate the accuracy of intraocular lens power calculation formulae in short eyes. A thorough literature search of PubMed, Embase, Cochrane Library, Science Direct, Scopus, and Web of Science databases was conducted for articles published over the past 21 years, up to July 2021. The mean absolute error was compared by using weighted mean difference, whereas odds ratio was used for comparing the percentage of eyes with prediction error within ±0.50 diopter (D) and ±1.0 D of target refraction. Statistical heterogeneity among studies was analyzed by using Chi-square test and I2 test. Fifteen studies including 2,395 eyes and 11 formulae (Barrett Universal II, Full Monte method, Haigis, Hill-RBF, Hoffer Q, Holladay 1, Holladay 2, Olsen, Super formula, SRK/T, and T2) were included. Although the mean absolute error (MAE) of Barrett Universal II was found to be the lowest, there was no statistically significant difference in any of the comparisons. The median absolute error (MedAE) of Barrett Universal II was the lowest (0.260). Holladay 1 and Hill-RBF had the highest percentage of eyes within ±0.50 D and ±1.0 D of target refraction, respectively. Yet their comparison with the rest of the formulae did not yield statistically significant results. Thus, to conclude, in the present meta-analysis, although lowest MAE and MedAE were found for Barrett Universal II and the highest percentage of eyes within ±0.50 D and ±1.0 D of target refraction was found for Holladay 1 and Hill-RBF, respectively, none of the formulae was found to be statistically superior over the other in eyes with short axial length. [ABSTRACT FROM AUTHOR]

Purpose: To assess the prediction accuracy of intraocular lens (IOL) formulas and study the effect of axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), and lens thickness (LT) on the accuracy of formulas using optic biometry.Methods: This study was performed on 164 eyes of 164 patients who underwent uneventful cataract surgery. Ocular biometry values were measured using Lenstar-900, and intraocular lens (IOL) power was calculated using the SRK/T, SRK II, Hoffer Q, Holladay 2, and Barrett Universal II formulas. We evaluated the extent of bias within each formula for different ocular biometric measurements and explored the relationship between the prediction error and the ocular parameters by using various IOL formulas.Results: The summarization of refractive prediction error and absolute prediction error for each IOL formulation was performed after adjusting the mean refractive error to zero. The deviation in the error values was minimum for SRK/T (0.265) followed by Holladay 2 (0.327) and Barret (0.382). Further, SRK/T had the lowest median (0.15) and mean (0.198) absolute error as compared to other formulations. For the above formulations, 100% of the eyes were in the diopter range of ±1.0. It was observed that the overall distribution of error was closer to zero for SRK/T, followed by Holladay 2 and then Barrett.Conclusion: In summary, we found that accuracy was better in SRK/T formula. We achieved a better understanding of how each variable in the formulas is relatively weighed and the influencing factors in the refraction prediction. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 < 0.001/=0.008). The number of refractive surprises was also significantly lower in the pretreatment group. [non-pretreatment/pretreatment: 9/2 (SRK/T); 8/1 (Barrett); 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. [ABSTRACT FROM AUTHOR]

Purpose: Optimization of lens constants is a critically important step that improves refractive outcomes significantly. Whether lens constants optimized for the entire range of axial length would perform equally well in short eyes is still a matter of debate. The aim of this study was to analyze whether lens constants need to be optimized specifically for short eyes.Methods: : This retrospective observational study was conducted at a tertiary care hospital in Central India. Eighty-six eyes of eighty-six patients were included. Optical biometry with IOLMaster 500 was done in all cases and lens constants were optimized using built-in software. Barrett Universal II, Haigis, Hill-RBF, Hoffer Q, Holladay 1, and SRK/T formulae were compared using optimized constants. Mean absolute error, median absolute error (MedAE), and percentage of eyes within ±0.25, ±0.50, ±1.00, and ±2.00 diopter of the predicted refraction, of each formula were analyzed using manufacturer's, ULIB, and optimized lens constants. MedAE was compared across various constants used by Wilcoxon signed-rank test and among optimized constants by Friedman's test. Cochran's Q test compared the percentage of eyes within ± 0.25, ±0.50, ±1.00, and ± 2.00 diopter of the predicted refraction. A value of P < 0.05 was considered statistically significant.Results: : Optimized constant of Haigis had significantly lower MedAE (P < 0.00001) as compared to manufacturers. However, there was no statistically significant difference between ULIB and optimized constants. Postoptimization, there was no statistically significant difference among all formulae.Conclusion: : Optimizing lens constants specifically for short eyes gives no added advantage over those optimized for the entire range of axial length. [ABSTRACT FROM AUTHOR]

Background: Intraocular lens (IOL) calculation using traditional formulas for post-corneal refractive surgery eyes can yield inaccurate results. This study aimed to compare the clinical accuracy of the newly developed Zhang & Zheng (ZZ) formula with previously reported IOL formulas.Study Design: Retrospective study.Methods: Post-corneal refractive surgery eyes were assessed for IOL power using the ZZ, Haigis-L, Shammas, Barrett True-K (no history), and ray tracing (C.S.O Sirius) IOL formulas, and their accuracy was compared. No pre-refractive surgery information was used in the calculations.Results: This study included 38 eyes in 26 patients. ZZ IOL yielded a lower arithmetic IOL prediction error (PE) compared with ray tracing (P = 0.04), whereas the other formulas had values like that of ZZ IOL (P > 0.05). The arithmetic IOL PE for the ZZ IOL formula was not significantly different from zero (P = 0.96). ZZ IOL yielded a lower absolute IOL PE compared with Shammas (P < 0.01), Haigis-L (P = 0.02), Barrett true K (P = 0.03), and ray tracing (P < 0.01). The variance of the mean arithmetic IOL PE for ZZ IOL was significantly smaller than those of Shammas (P < 0.01), Haigis-L (P = 0.03), Barrett True K (P = 0.02), and ray tracing (P < 0.01). The percentages of eyes within ± 0.5 D of the target refraction with the ZZ IOL, Shammas, Haigis-L, Barrett True-K, and ray-tracing formulas were 86.8 %, 45.5 %, 66.7 %, 73.7 %, and 50.0 %, respectively (P < 0.05 for Shammas and ray tracing vs. ZZ IOL).Conclusions: The ZZ IOL formula might offer superior outcomes for IOL power calculation for post-corneal refractive surgery eyes without prior refractive data. [ABSTRACT FROM AUTHOR]

The statistical characteristics of biometry and refractive error in a large sample of cataractous Cuban patients are presented, comparing between sexes and age groups. All patients were studied at the Cuban Institute of Ophthalmology "Ramón Pando Ferrer," La Habana. The sample consists of 28252 eyes of 25068 patients, subjected to cataract surgery during the time period between 2006 and 2019. Their biometry was obtained using IOL Master devices; also, visual acuity, refraction, and corneal power were registered. After surgery, the visual acuity and refraction were measured. The refractive prediction error was determined. For patients with both eyes registered, anisometropia was also calculated. Age and sex were used to segment the data. The preoperative biometric parameters show highly significant differences between sexes, with male eyes being longer and with a deeper anterior chamber but with a thinner lens. Also, keratometry shows highly significant differences, with female eyes being steeper than male. Before surgery, both sexes have myopic eyes as average, with males being more myopic than females (p < 0.001). After surgery, the average spherical equivalent is −0.36 D and female eyes are more myopic than males (p < 0.001). Visual acuity with and without distance correction has a significant increase after surgery. These results are of importance not only for Cuba but also for other countries with a large Cuban population and/or similar ethnic composition, such as the USA (particularly the south of Florida), Spain, and many countries in Latin America. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study is to evaluate the accuracy of three newer generation formulae (Barrett Universal II, EVO, Hill-RBF 2.0) for calculation of power of two standard IOLs-the Acrysof IQ and Tecnis ZCB00 across all axial lengths.Methods: In this retrospective series, 206 eyes of 206 patients, operated for cataract surgery with above two IOLs over the last 6 months, were included in the study. Preoperative biometry measurements were obtained from LenstarLS900. By using recommended lens constants, the mean error for each formula was calculated and compared. Then, the optimized IOL constants were calculated to reduce the mean error to zero. Mean and median absolute errors were calculated for all eyes and separately for short (AL<22.5 mm), medium (22.5-24.5 mm), and long eyes (>24.5 mm). Absolute errors and percentages of eyes within prediction errors of ±0.25 D, ±0.50 D, ±0.75 D, and ±1.00 D were compared.Results: Prediction error with using recommended lens constants was significantly lower in the Barrett Universal II formula as compared to the other two formulae. However, after optimizing lens constants, there were no significant differences in the absolute errors between the three formulae. The formulae ranked by mean absolute error were as follows: Barrett Universal II (0.304 D), EVO (0.317 D), and Hill-RBF (0.322) D. There were no significant differences between absolute errors in the three formulae in each of the short-, medium-, and long-eye subgroups.Conclusion: With proper lens constant optimization, the Barrett Universal II, EVO, and Hill-RBF 2.0 formulae were equally accurate in predicting IOL power across the entire range of axial lengths. [ABSTRACT FROM AUTHOR]

Purpose: To compare the accuracy of intraocular lens (IOL) power calculation formula predictions (Barrett Universal II, Emmetropia Verifying Optical [EVO] 2.0, Haigis, Hill-RBF 2.0, Holladay 1, Holladay 2, Hoffer Q, Kane, Olsen, and SRK/T) when using the Alcon SA60AT IOL of 30 or greater diopter (D) power. Setting: Kaiser Permanente, California, USA. Design: Multicenter retrospective consecutive case series. Methods: Data from patients having uneventful cataract surgery with insertion of a >=30 D SA60AT IOL and preoperative LENSTAR 900 biometry were included. A single eye per qualifying patient was randomly selected for inclusion in the analysis. Lens constants were optimized using a large dataset of the same IOL model including the full range of axial lengths. The optimized lens constants were then used to calculate the predicted refraction for each formula, which was compared with the actual refractive outcome to give the prediction errors. Results: Included in the study were 182 eyes of 182 patients. From highest to lowest, the percentage of eyes with a prediction error within +/-0.50 D was the Kane (58.8%), EVO 2.0 (57.7%), Haigis (55.5%), Holladay 2 (54.9%), Olsen (53.3%), Holladay 1 (50.5%), Hill-RBF 2.0 (43.9%), SRK/T (42.9%), Barrett Universal II (36.8%), and Hoffer Q (35.7%) formulas. The Kane formula had a statistically significant lower mean absolute prediction error compared with all formulas (P <.05) except the EVO 2.0 formula. Conclusions: The Kane formula had the lowest prediction error of the formulas studied, which was statistically significant compared with all formulas except the EVO 2.0 formula. [ABSTRACT FROM AUTHOR]

Purpose: To analyze the reliability of the refractive results prediction obtained in intraocular lens (IOL) calculation using bicylindric power calculation method, with the use of steep and flat keratometry readings compared with the classical mean keratometry calculation method.Methods: Fifty-seven eyes of 57 subjects who underwent cataract surgery were included in this prospective study. Optical biometry was performed with IOLMaster 700 and IOL power calculation was performed using both keratometry readings and the surgically induced astigmatism. Four weeks after surgery, subjective refraction was done. Finally, results obtained with both IOL calculation methods were compared.Results: Mean spherical equivalent using bicylindric IOL power calculation method was -0.082 ± 0.296D, and achieved mean spherical equivalent using classical IOL power method with Haigis formula was -0.088 ± 0.405D. Achieved mean spherical equivalent obtained in subjective refraction after surgery was -0.101 ± 0.265D. Linear correlation between bicylindric method spherical equivalent calculation and achieved spherical equivalent was statistically significant (r = 0.761, P < 0.001), also correlation between Haigis spherical equivalent calculation and achieved spherical equivalent was statistically significant (r = 0.339, P = 0.010). Emmetropia was achieved in 49 of 57 (85.86%) subjects and bicylindric method calculated that 49 of 57 (85.86%) of subjects would get emmetropia (P = 1.000). Classical IOL power calculation estimated that 38/57 subjects would get emmetropia (66.67%) (P = 0.026).Conclusion: The IOL power calculation including both keratometry readings and surgically induced astigmatism seems to be more accurate and provides more precision in refractive prediction than classical calculation method. [ABSTRACT FROM AUTHOR]

Purpose: To study the effect of choice of anesthesia on the refractive outcomes of intraoperative aberrometry (IA) for intraocular lens power calculation in cataract surgeries.Methods: This prospective, interventional nonrandomized cohort study was conducted at a tertiary care hospital between March and August 2018. A total of 178 patients with age-related cataract were allocated into two groups. Group 1 received peribulbar anesthesia using a mixture of xylocaine 2% + adrenaline 0.125 mg/ml + hyaluronidase 15 IU/ml with a 23G, 32 mm needle, while Group 2 received topical anesthesia with proparacaine hydrochloride 0.05% drops. Intraoperative aphakic measurements and IOL power calculations were obtained in all patients with the optiwave refractive analysis (ORA) system. Analysis was performed to compare the baseline parameters and postoperative manifest refraction at month 1.Results: A total of 89 patients were included in group 1 and 89 in group 2. At baseline, the axial lengths (P = 0.66) and mean keratometry (P = 0.91) were comparable. The quality measure of captured wavefront data was comparable (0.25) between the groups. Also, the postoperative mean refractive spherical equivalents were comparable between the two groups (P = 0.98) at one month.Conclusion: IA can be utilized well for cataract surgeries performed under local anesthesia with good quality of captured wavefront, provided the eye can be aligned in centre with the fixation light of ORA. [ABSTRACT FROM AUTHOR]

Purpose: To objectively evaluate surgically induced astigmatism (SIA) after phacotrabeculectomy using keratometry and topography and to compare the magnitude of SIA and the refractive outcomes of single-site and twin-site phacotrabeculectomies.Methods: Forty prospective subjects were enrolled in the study and were randomized into single-site and twin-site cohorts. SIA was objectively assessed using keratometry and Orbscan before and at three months after surgery. For both cohorts, the changes in SIA were assessed using power vector analysis compared at the third month after surgery.Results: Each cohort consisted of 20 eyes. The preoperative parameters and postoperative IOP were comparable and similar, respectively, in both the cohorts (P = 0.1). Majority of the patients in both the cohorts had preoperative against-the-rule (ATR) astigmatism. The median change in SIA at the three-month postoperative visit was similar in both the cohorts, with a small increase in ATR astigmatism. Although the SIA change measured by keratometry in the J0 component was similar in both the groups (P = 0.54), that of J45 was significantly different (P = 0.01). However, the median change in SIA was similar in both the groups for both the J0 (P = 0.52) and J45 components (P = 0.94) when measured by Orbscan. The SIA in both the groups measured with keratometry (P = 0.62) and topography (P = 0.52) were clinically and statistically similar. In both the groups, the refraction was similar at 1 month and 3 months.Conclusion: The SIA as measured with keratometry and topography was similar in the single-site and twin-site phacotrabeculectomy cohorts at the end of 3-months. The postoperative refraction was stabilized in 1-month in both the groups. [ABSTRACT FROM AUTHOR]

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Purpose: To determine the refractive astigmatism following toric intraocular lens (tIOL) implantation without consideration of posterior keratometric astigmatism with a conventional tIOL calculator for eyes with low keratometric astigmatism (0.75D to 2.5D) and to theoretically compare the outcomes with predicted refractive astigmatism using a calculator with Barrett's formula. Methods: 34 eyes (34 patients) were assessed with Scheimpflug imaging and underwent tIOL implantation employing conventional tIOL calculator. Eyes were grouped on preoperative keratometric astigmatism as against-the-rule (ATR), with-the-rule (WTR), and oblique (OB). The refractive astigmatism was assessed at 1, 3, 6 and 12 months postoperatively and was classified as ATR, WTR, and OB. Theoretical refractive astigmatism calculations were performed for the same eyes using Barrett's formula. Results: Preoperatively keratometric astigamtism was ATR, WTR, and OB in 32%, 53% and 15% of eyes. At 12 months, in ATR, WTR and OB groups, 45.5%, 16.7% and 60% had ATR refractive astigmatism; 16.7%, 0%, and 20% had WTR refractive astigmatism; 55.6%, 54.5% and 20% were emmetropic (no sphere and cylinder) respectively. There was a significant difference between the theoretical predicted postoperative refractive astigmatism using conventional tIOL calculator and Barrett's formula (P <.05). Postoperative refractive astigmatism was not significantly different from the theoretical predicted refractive astigmatism with Barrett's formula but it was significantly higher than that with a conventional tIOL calculator. Conclusions: At 12 months, with a conventional tIOL calculator, postoperative emmetropia is achieved in half, two third and one-fifth of eyes with preoperatively ATR, WTR, and OB keratometric astigamtism respectively. Around 1/4th WTR keratometric astigamtism eyes preoperatively were overcorrected to ATR refractive astigmatism whereas ½ATR remained undercorrected at 12 months Outcomes achieved were dissimilar to predicted outcomes with a conventional tIOL calculator but similar to those with Barrett's formula. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to determine the ocular biometry characteristics and corneal astigmatisms using partial coherence laser interferometry in patients aged 40 years or above undergoing cataract surgery in a medical college in North-East India.Methods: In a hospital-based cross-sectional study, ocular biometry characteristics such as axial length (AL), anterior chamber depth (ACD), white-to-white (WTW) diameter, corneal power (K), and corneal astigmatisms (D) of consecutive eligible cataract patients in a medical college in North-East India between January 2015 and December 2017 were determined using the intraocular lens (IOL) master. Height and weight were also measured.Results: A cross-sectional study evaluated ocular biometry characteristics of 641 eyes in 641 eligible patients. The mean age was 64.04 ± 10.81 years. The mean AL, ACD, WTW, corneal power, IOL power, and body mass index (BMI) were 23.34 ± 1.12 mm, 3.12 ± 0.39 mm, 11.92 ± 0.54 mm, 44.41 ± 1.50 diopter (D), 20.53 ± 2.79 D, and 26.12 ± 4.32, respectively. Against-the-rule, with-the-rule, and oblique astigmatisms were 48.4%, 33.2%, and 18.4%, respectively. Corneal astigmatism of ≥1 D was found in 292 eyes (45.55%) and >1.5 D in 182 eyes (28.39%). AL had statistically significant correlation with ACD, WTW, K, IOL power, height and weight but not with age. By multivariate analysis, AL was found to be associated with ACD, WTW, K and IOL power (P ≤ 0.05). The mean AL was negatively correlated with the mean K (R-square 0.138).Conclusion: This study is likely to provide the initial normative data for ocular biometry values in Indian adults 40 years or above, because such data is lacking in Indians using the IOL master. This will also help ophthalmologists in planning and improving the quality of surgical outcomes in phacoemulsification and phacorefractive surgeries by choosing the appropriate IOL and incision location. [ABSTRACT FROM AUTHOR]

Purpose: To compare the outcomes of intraoperative wavefront aberrometry versus optical biometry alone for intraocular lens (IOL) power calculation in eyes undergoing cataract surgery with monofocal IOL implantation.Methods: Preoperative data were obtained with the IOLMaster. Intraoperative aphakic measurements and IOL power calculations were obtained in some patients with the optiwave refractive analysis (ORA) system. Analysis was performed to determine the accuracy of monofocal IOL power prediction and postoperative manifest refraction at 1 month of the ORA versus IOLMaster.Results: Two hundred and ninety-five eyes reviewed, 61 had only preoperative IOLMaster measurements and 234 had both IOLMaster and ORA measurements. Of these 234 eyes, 6 were excluded, 107 had the same recommended IOL power by ORA and IOLMaster. Sixty-four percent of these eyes were within ±0.5D. 95 eyes had IOL power implantation based on ORA instead of IOLMaster. Seventy percent of these eyes were within ±0.5D of target refraction. 26 eyes had IOL power chosen based on IOLMaster predictions instead of ORA. Sixty-five percent were within ±0.5D. In the group with IOLMaster without ORA measurements, 80% of eyes were within ±0.5D of target refraction. The absolute error was statistically smaller in those eyes where the ORA and IOLMaster recommended the same IOL power based on preoperative target refraction compared to instances in which IOL selection was based on ORA or IOLMaster alone. Neither prediction errors were statistically different between the ORA and IOLMaster alone.Conclusion: Intraoperative wavefront aberrometry with the ORA system provides postoperative refractive results comparable to conventional biometry with the IOLMaster for monofocal IOL selection. [ABSTRACT FROM AUTHOR]

Background: To assess the constants and formula for aphakia correction with iris-claw IOLs to achieve the best refractive status in cases of late in-the-bag IOL complex dislocation.Methods: A literature search was performed. The following data were obtained: Iris-claw IOL model, Iridal or retroiridal enclavation, A-constant, ultrasound or optical biometry, formula employed and refractive outcomes. Acceptable emmetropia was considered if the resulting spherical equivalent (SE) was within ±1.00 D.Results: The majority of the studies used SRK/T formula (66.6%). The 88.9% of the reports obtained a SE within ±1.00 D. Using A-115 for ultrasound biometry and A-115.7 for optical biometry and SRK/T formula, the emmetropia (±1.00 D) of SE, was able to get near 100% of reported cases over the pupil implantation. However, the emmetropia decreased to 80% when the enclavation is retropupilar using the same formula. The A-constant can vary from 116.7 to 117.5 for retropupilar enclavation.Conclusions: Using A-115 for ultrasound biometry and A-115.7 for optical biometry and SRK/T formula, ±1.00 D of SE, is able to get near 100% of cases. Nevertheless, ±1.00 D of SE decreased to 80% of the cases when the enclavation is retropupilar. [ABSTRACT FROM AUTHOR]

Background: To evaluate how differences in ocular biometry affects the Hoffer Q, Holladay 1, SRK/T, and Haigis intraocular lens power calculation formulae predictions.Methods: This study was performed on 91 eyes of 91 patients who underwent uneventful cataract surgery. Ocular biometry values were measured using the IOL Master 500, and intraocular lens (IOL) power was calculated using the Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. We calculated the expected difference (ED) of each 3rd generation formula from the Haigis formula by subtracting the predicted refraction of the Haigis formula from the predicted refraction of each 3rd generation formula. Post-operative anterior chamber depth (ACD) was measured at 1 month after surgery using the IOL master. We calculated errors of each formula by subtracting predicted from manifest refraction at post-operative 1 month. Correlation analysis was performed between ocular biometry values, formula expectation values, formula errors and absolute formula errors.Results: Multiple regression analysis revealed that preoperative ACD was the only significant factor for ED prediction in all of the 3rd generation formulas. For mean errors, axial length and post-operative 1-month change of ACD (delta ACD) correlated significantly with the errors in all 3rd generation formulas, but not with errors of the Haigis formula. Median absolute error (MedAE) of the formulas were 0.40 D for the Hoffer Q formula, 0.37 D for the Holladay formula, 0.34 D for the SRK/T formula, and 0.41 D for the Haigis formula. The MAE of the formulas were 0.50 ± 0.47 D for the Hoffer Q formula, 0.50 ± 0.50 D for the Holladay formula, 0.47 ± 0.51 D for the SRK/T formula, and 0.50 ± 0.47 D for the Haigis formula.Conclusion: Regarding ED between the third generation and Haigis formulas, preoperative ACD demonstrated the greatest influence. Calculating mean absolute errors of the formulas, all IOL formulas showed excellent and comparable accuracy. Post-operative change (delta) of ACD correlated significantly with errors of third generation formulas according to simulated ACD. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate the prediction accuracy of postoperative refractions using partial coherence interferometry (IOL-Master) and applanation ultrasound (AL-3000) assisted with corneal topography (TMS-4) in eyes that had undergone myopic laser-assisted in situ keratomileusis (LASIK).Methods: Haigis-L formula, Koch-Maloney method using Haigis formula, Shammas clinically derived K-value (simulated keratometric value) correction (Shammas c.d.) using Haigis formula, and Shammas post-LASIK (Shammas-PL) formula were used in eyes with myopic LASIK. Constants were derived from the optimized constants in 133 virgin eyes. Refractive outcomes were determined by streak retinoscopy and subjective manifest refraction. Methods and formulas were evaluated by mean error (ME), standard deviation (SD), range of error, mean absolute error (MAE), median absolute error, 95% confidence interval of MAE, and percentage of eyes within ±0.5 diopter (D), ±1.0 D, and ±1.5 D of prediction.Results: SDs of the Haigis-L, Koch-Maloney method using the Haigis formula, Shammas c.d. using the Haigis formula, and the Shammas-PL formula using IOL-Master were 0.721, 0.695, 0.695, and 0.698; and those using AL-3000 assisted with TMS-4 were 0.782, 0.741, 0.743, and 0.778, respectively.Conclusions: No-history methods that corrected corneal power with measurements using IOL-Master were promising in myopic post-LASIK eyes, but still a gap in prediction accuracy exists between virgin eyes and post-LASIK eyes. [ABSTRACT FROM AUTHOR]

Background: The SRK/T formula is one of the third generation IOL calculation formulas. The purpose of this study was to evaluate the performance of the SRK/T formula in predicting a target refraction ±1.0D in short and long eyes using ultrasound biometry after phacoemulsification. Methods: The present study was a retrospective analysis, which included 38 eyes with an AL < 22.0 mm (short AL), and 62 eyes ≥24.6 mm (long AL) that underwent uncomplicated phacoemulsification. Preoperative AL was measured by ultrasound biometry and SRK/T formula was used for IOL calculation. Three different IOLs were implanted in the capsular bag. The prediction error was defined as the difference between the achieved postoperative refraction, and attempted predicted target refraction. Statistical analysis was performed with SPSS V21. Results: In short ALs, the mean age was 65.13 ± 9.49 year, the mean AL was 21.55 ± 0.45 mm, the mean K1 and K2 were 45.76 ± 1.77D and 46.09 ± 1.61D, the mean IOL power was 23.96 ± 1.92D, the mean attempted (predicted) value was 0.07 ± 0.26D, the mean achieved value was 0.07 ± 0.63 D, the mean PE was 0.01 ± 0.60D, and the MAE was 0.51 ± 0.31D. A significant positive relationship with AL and K1, K2, IOL power and a strong negative relationship with PE and achieved postoperative was found. In long ALs, the mean age was 64.05 ± 7.31 year, the mean AL was 25.77 ± 1.64 mm, the mean K1 and K2 were 42.20 ± 1.57D and 42.17 ± 1.68D, the mean IOL power was 15.79 ± 5.17D, the mean attempted value was -0.434 ± 0.315D, the mean achieved value was -0.42 ± 0.96D, the mean PE was -0.004 ± 0.93D, the MAE was 0.68 ± 0.62D. A significant positive relationship with AL and K1, K2 and a significant positive relationship with PE and achieved value, otherwise a negative relationship with AL and IOL power was found. There was a little tendency towards hyperopic for short ALs and myopic for long ALs. The majority of eyes (94.74 %) for short ALs and (70.97 %) for long ALs were within ±1 D of the predicted refractive error. No significant relationship with PE and IOL types, AL, K1, K2, IOL power, and attempted value, besides with MAE and AL, K1, K2, age, attempted, achieved value were found in both groups. Conclusion: The SRK/T formula performs well and shows good predictability in eyes with short and long axial lengths. [ABSTRACT FROM AUTHOR]

Objective: To assess ocular biometric parameters by optical biometry and to observe a possible spherical refractive difference, as well as its variation based on estimated preoperative calculation and the spherical refraction post cataract surgery by phacoemulsification with intraocular lens implant (IOL). Methods: After reviewing 252 electronic medical records between 2013 and 2014, 117 adult patients (189 eyes) were selected. The patients underwent phacoemulsification with foldable IOL implantation by the same surgeon and were examined by IOLMaster® 500. The IOL power was calculated using the Haigis formula. The Wilcoxon test was applied to identify the existence of significant differences (p<0.05) between the spherical expected refraction (SER) and the final spherical refraction (FSR) of the eyes. Results: There were operated 98 right eyes (OD) and 91 left (OS). A calculation of the variation between FSR and SER indicated that 55% of the OD reached results within ± 0.5 diopters (D) and 89% within ± 1D. With respect to OS, 46% achieved results within ± 0.5D and 78% within ± 1D. Conclusion: Optical biometry is a reliable, predictable and reproducible method to estimate the FSR of both eyes. [ABSTRACT FROM AUTHOR]

Background To evaluate the accuracy of predicted refraction using multifocal intraocular lenses ( IOLs) with power calculation based on two biometric devices and multiple IOL power calculation formulas. Design A retrospective study conducted in a private practice ophthalmology clinic. Participants Seventy-three eyes of 48 patients were evaluated. Methods Consecutive cases of eyes that had undergone successful cataract surgery with an implantation of a multifocal IOL ( SN6 AD1, Alcon Laboratories, Inc., Fort Worth, TX, USA) by a single surgeon were enrolled. Patients were meticulously screened for suitability for a multifocal IOL implantation according to our clinic guidelines. Two biometric measurement devices ( IOLMaster-500 [ Carl Zeiss Meditec AG, Jena, Germany] and Lenstar- LS900 [ Haag- Streit AG, Koeniz, Switzerland]) were used under strict validation criteria to evaluate the predicted refraction errors for the Holladay 1, SRK/ T, Hoffer Q, Haigis, Holladay 2, Barrett Universal II and Olsen formulas. Main Outcome Measures Predicted refractive sphere equivalent ( RSE) errors. Results The measurements obtained from the two biometric devices were highly correlated. The standard deviation of the error in predicted RSE and the median absolute error were similar for the IOLMaster and the Lenstar devices using all formulas, ranging from 0.27 dioptres ( D) to 0.31 D and from 0.15 D to 0.21 D, respectively. A high percentage of eyes had an error in predicted RSE within ±0.5 D from target refraction, ranging from 86.3% to 93.2%. Conclusions High accuracy can be achieved in multifocal IOL power calculations by appropriate patient selection, precise biometry and appropriate IOL calculation formulas. [ABSTRACT FROM AUTHOR]

Objective To document intraocular measurements and predict intraocular lens ( IOL) power specific to the bald eagle. Animals studied Eleven adult, captive bald eagles. Procedures Axial globe length ( AGL), anterior chamber depth ( ACD), crystalline lens thickness ( CLT), and the distance from the cornea to the posterior lens capsule ( CPLC) were measured in eight adult bald eagles using B-mode with vector A-mode ultrasound. Keratometry was done on four eagles. Two estimates for postoperative anterior chamber depth ( PACD) were obtained from four aphakic eyes from three eagles by measuring from the apex of the anterior cornea to the center of an imaginary line that would connect the remaining edges of the anterior lens capsule across the capsulorhexis ( PACD1) and from the apex of the anterior cornea to halfway between the anterior and posterior lens capsule ( PACD2). IOL strength was predicted using the Colenbrander, Binkhorst, and Fyodorov theoretical formulas. Results Mean ± SD biometry for phakic eyes was AGL = 26.57 ± 0.45 mm, ACD = 4.45 ± 0.18 mm, CLT = 5.49 ± 0.14 mm, and CPLC = 10.00 ± 0.33 mm. Mean predicted PACD1 was 6.1 ± 0.66 mm, and PACD2 was 6.4 ± 0.70 mm. Mean horizontal and vertical corneal refractive power was 39.91 ± 0.43 diopters (D) and 40.02 ± 0.08 D, respectively. Calculated IOL power ranged from +16.4 to 17.4 D. Conclusions Calculations using ultrasonographic biometry, keratometry, and theoretical IOL formulas suggest that the strength of an IOL necessary to return an aphakic bald eagle to emmetropia is between +16.4 and +17.4 D. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the accuracy of the C constant for ray tracing–assisted intraocular lens (IOL) power calculation. Design: Case series. Setting: Public university hospital and private clinic. Methods: Preoperatively, all intraocular distances were measured using laser biometry. Various IOL designs were studied; powers ranged from −5.0 diopters (D) to +38.0 D. The IOL power calculation was performed with the Olsen formula using the C constant and compared with the Haigis, Hoffer Q, Holladay 1, and the SRK/T formulas on optimized datasets. Outcome measures were the error of the prediction, expressed as the arithmetic error, and the absolute error between the observed refraction and the predicted refraction. Results: Two thousand forty-three cases from the 2 centers were studied. No significant differences were found between the Haigis, Hoffer Q, Holladay 1, and SRK/T formulas with the exception of the SRK/T formula, which performed better than the other thin-lens formulas in eyes with an axial length (AL) greater than 27.0 mm (P<.01). Compared with the SRK/T formula, the Olsen formula showed an improvement of 15% and 14% in the mean absolute error and a 39% and 85% reduction in the number of large errors (>1.0 D) for the 2 series, respectively (P<.0001). Contrary to the Olsen formula, all thin-lens formulas showed a significant bias in terms of the AL, keratometry reading, and anterior segment length (P<.0001). Conclusion: The C constant is a promising concept for ray tracing–assisted IOL power calculation. Financial Disclosure: Dr. Olsen is a shareholder of IOL Innovations Aps, manufacturer of the Phacooptics IOL calculation software. Dr. Hoffmann has no financial or proprietary interest in any material or method mentioned. [Copyright &y& Elsevier]

A bstract Background: To assess the accuracy of Haigis, Holladay 1, Hoffer Q and SRK/T formulae in eyes with axial length of <22.00 mm. Design: Retrospective comparative analysis. Participants: 163 eyes of 97 patients undergoing phacoemulsification and intraocular lens (IOL) implantation. Methods: Ocular biometry was performed using IOLMaster laser interferometry. Predicted refractive outcomes before and after lens constant adjustment were compared to actual refractive outcomes. Main Outcome Measures: Mean prediction (ME) and mean absolute errors (MAE) with standard deviations (±SD). Results: Mean preoperative spherical equivalent was +5.44D ± 1.97D. Mean axial length was 21.20 mm ± 0.60 mm. Using standard IOL constants the MAE for Hoffer Q (0.62D, ±0.52D) and Holladay 1 (0.66D ± 0.52D) were significantly lower than SRK/T (MAE 0.91D ± 0.64D; P = <0.0005 and P = 0.001 respectively), but not Haigis (MAE 0.82D ± 0.83D, P = 0.071 and 0.22 respectively). MAEs for all formulae were significantly reduced by IOL constant adjustment (all P = <0.001). Following this there was no statistically significant difference in MAEs between formulae (range 0.50-0.57D, P = 0.57). Increasing MAE was significantly associated with reducing axial length and increasing IOL power for all formulae. For bilateral cases, prediction errors between eyes were significantly correlated across all formulae (all P = <0.0001) and explained 32-42% of the variance in prediction error between eyes. Conclusions: Prediction of postoperative refraction in patients with short axial lengths is challenging and at the limit of current, popular IOL formulae. There is now a clear need for prospective studies to assess latest generation IOL formulae such as Holladay 2 or Olsen in small eyes. [ABSTRACT FROM AUTHOR]

Purpose: Comparison of postoperative refraction results using ultrasound biometry with closed immersion shell and optical biometry. Patients and method: Three hundred and sixty-four eyes of 306 patients (age: 70.6 ± 12.8 years) underwent cataract surgery where intraocular lenses calculated by SRK/T formula were implanted. In 159 cases immersion ultrasonic biometry, in 205 eyes optical biometry was used. Differences between predicted and actual postoperative refractions were calculated both prior to and after optimization with the SRK/T formula, after which we analysed the similar data in the case of Holladay, Haigis, and Hoffer-Q formulas. Mean absolute error (MAE) and the percentage rate of patients within ±0.5 and ±1.0 D difference in the predicted error were calculated with these four formulas. Results: MAE was 0.5-0.7 D in cases of both methods with SRK/T, Holladay, and Hoffer-Q formula, but higher with Haigis formula. With no optimization, 60-65 % of the patients were under 0.5 D error in the immersion group (except for Haigis formula). Using the optical method, this value was slightly higher (62-67 %), however, in this case, Haigis formula also did not perform so well (45 %). Refraction results significantly improved with Holladay, Hoffer-Q, and Haigis formulas in both groups. The rate of patients under 0.5 D error increased to 65 % by the immersion technique, and up to 80 % by the optical one. Conclusions: According to our results, optical biometry offers only slightly better outcomes compared to those of immersion shell with no optimized formulas. However, in case of new generation formulas with both methods, the optimization of IOL-constants give significantly better results. [ABSTRACT FROM AUTHOR]

Purpose: To determine whether the correlation between corneal power (K) and axial length (AL) can be used for intraocular lens (IOL) power calculation when biometric data are incomplete. Setting: Developing regions served by United States Navy humanitarian assistance missions. Design: Case series. Methods: Measurements of K and AL were collected from all adult cataract surgery charts and used to calculate emmetropic IOL powers. A formula for estimating K or AL was derived by Deming regression analysis. The emmetropic IOL powers were calculated by hypothetical scenarios as follows: (1) K estimated from the formula and measured AL, (2) mean population K and measured AL, (3) measured K and estimated AL, and (4) measured K and mean population AL. The mean absolute refractive error (MAE) was calculated for each hypothetical scenario and an additional scenario (scenario 5) using single IOL power for all eyes. The MAEs were compared with a paired t test. Results: The formula derived from Deming regression analysis was K = 74.56 − 1.317 × AL. The MAE for the scenarios were (1) 0.90 diopters (D), (2) 1.11 D, (3) 1.91 D, (4) 1.55 D, and (5) 1.22 D. The MAE for scenario 1 was significantly less (P<.01) than that for scenarios 2 and 5. The MAE for scenario 5 was significantly less than that for scenarios 3 and 4. Conclusions: The correlation between K and AL can be used to improve accuracy of IOL calculation when K is unavailable. When the AL is unavailable, the mean population IOL power is most accurate. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the accuracy of intraocular lens (IOL) power calculation after an intrastromal femtosecond laser procedure to treat presbyopia using a theoretic approach. Setting: International Vision Correction Research Centre, Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany. Design: Nonrandomized clinical trial. Methods: Preoperatively and 12 months after intrastromal femtosecond laser treatment (IntraCor) of presbyopia, biometry was performed by partial coherence interferometry (PCI) (IOLMaster). The postoperative keratometry (K) values and IOL power calculation formulas (Holladay I, Haigis, SRK/T, Hoffer Q) were compared with results derived from the clinical history method, taking the manifest refraction change into account. Results: The study enrolled 25 patients (median age 54 years). Three eyes were excluded for age-related lens changes. The median spherical equivalent change in the other 22 eyes was −0.38 diopter (D). The median difference in K values between the clinical history method and PCI was −0.21 D, resulting in a median IOL power difference between −0.23 D (SRK/T) and −0.29 D (Haigis) (range −1.58 to +1.00 D). The IOL power was underestimated in 59.1% of cases with the Hoffer Q and 63.6% of cases with the Holladay I, Haigis, and SRK/T. There was a difference of ±0.75 D in 72.7% of eyes using the Holladay I, Haigis, and Hoffer Q and in 86.4% of eyes using the SRK/T. Neither K values nor IOL power differences were statistically significant (P > .17). Conclusion: Intraocular lens power calculation using modern standard formulas incorporated in a PCI biometry device after intrastromal femtosecond presbyopia treatment was reliable, with minimum underestimation on average. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. [Copyright &y& Elsevier]

Purpose: To report the value of dual biometry in the detection of biometry errors. Methods: Study 1: retrospective study of 224 consecutive cataract operations. The intraocular lens power calculation was based on immersion biometry. Study 2: immersion biometry was compared with optical coherence biometry (OCB) in terms of axial length, anterior chamber depth, keratometry readings and the recommended lens power to achieve emmetropia. Study 3: prospective study of 61 consecutive cataract operations. Both immersion and OCB were performed, but lens power calculation was based on the latter. Results: Study 1: 115 (86%), 101 (75.4%), 90 (67.2%) and 50 (37.3%) of postoperative spherical equivalents were within ±1.5 dioptres (D), ±1.25 D, ±1 D and ±0.5 D of the target, respectively. Study 2: excellent agreement between axial length readings, anterior chamber depth readings and keratometry readings by immersion biometry and OCB was observed (reflected in a mean bias of −0.065 mm, −0.048 mm and +0.1803 D, respectively, in association with OCB). Agreement between the lens power recommended by each technique to achieve emmetropia was poor (mean bias of +1.16 D in association with OCB), but improved following appropriate modification of lens constants in the Accutome A-scan software (mean bias with OCB = −0.4 D). Study 3: 37 (92.5%) and 23 (57.5%) of operated eyes achieved a postoperative refraction within ±1 D and ±0.5 D of target, respectively. Conclusion: Systematic errors in biometry can exist, in the presence of acceptable postoperative refractive results. Dual biometry allows each biometric parameter to be scrutinized in isolation, and identify sources of error that may otherwise go undetected. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate intraocular lens (IOL) power calculation using a new optical low-coherence reflectometry (OLCR) biometer and compare the results with those obtained with a partial coherence interferometry (PCI) optical biometer. Setting: International Vision Correction Research Centre, Department of Ophthalmology, University of Heidelberg, Heidelberg, Germany. Methods: Biometry measurements in eyes of cataract patients were performed by the same examiner with an OLCR biometer (Lenstar LS 900/Allegro Biograph) and a PCI optical biometer (IOLMaster). After determination of axial length (AL), corneal radii values by keratometry (R1 and R2), and anterior chamber depth (ACD), power calculation for an AcrySof MA60AC IOL was compared between the 2 devices using 4 formulas and the corresponding IOL constants. The target was emmetropia. Results: One hundred eyes of 100 cataract patients (mean age 70.0 years ± 10.6 [SD]) were measured. Of the biometry parameters, the only statistically significant differences between the 2 devices were in R2 (mean difference 0.02 ± 0.05 mm), (R1 + R2)/2 (mean difference 0.01 ± 0.04 mm), and ACD (mean difference 0.05 ± 0.11 mm) (P<.01, Wilcoxon test). The mean differences in IOL power calculations using the 4 formulas were not statistically significant between the 2 devices (P>.01, Wilcoxon test). Conclusion: The OLCR biometry device provided precise and valid measurements and thus can be used for the preoperative examination of cataract patients. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. [Copyright &y& Elsevier]

Purpose: To compare the optical biometry measurements and intraocular lens (IOL) power estimation using the IOLMaster (Carl Zeiss Meditec, Dublin, CA) in phakic eyes and eyes with hydrophobic acrylic lenses. Design: Observational cross-sectional study. Participants: A total of 156 patients (226 eyes). Methods: The IOLMaster measurements (IOLM-1) were performed before phacoemulsification and reexamined 3 months postoperatively (IOLM-2). One of the foldable acrylic IOLs (AcrySof SA60AT, SN60WF, or SN60D3, Alcon Laboratories Inc., Dallas, TX) was implanted. Main Outcome Measures: The expected refraction and estimation error calculated from IOLM-1 using the SRK II, SRK/T, and Haigis formulae were compared with the residual refraction 3 months postoperatively. The power of the implanted IOL and IOLM-2 measurement data were used to re-estimate the postoperative expected refraction in pseudophakic eyes. The difference in expected refraction and estimation error between phakic and pseudophakic eyes was studied. Differences in the anterior chamber depth and axial length measured by IOLM-1 and IOLM-2 were analyzed and correlated with the estimation error. Results: The IOLMaster measured an axial length 0.10±0.15 mm shorter in pseudophakic eyes (P<0.001). Calculations from IOLM-2 gave a significantly more hyperopic expected refraction than IOLM-1, with an averaged 0.20±0.46 diopters (D), 0.18±0.45 D, and 0.65±0.59 D calculated by the SRK II, SRK/T, and Haigis formulae, respectively. There was no significant difference among the 3 IOLs. The difference in estimation error correlated with the difference in axial length and anterior chamber depth (P<0.001 for the SRK II, SRK/T, and Haigis formulae). However, the correlation was strongest when the Haigis formula was used for the calculation. Conclusions: The expected refraction in pseudophakic eyes differed significantly from that in phakic eyes by the IOLMaster depending on the IOL formulae used for the calculation rather than the type of IOL. An adjustment of target refraction by 0.20 to 0.65 D toward the hyperopic side of the desired refraction could be considered when using optical biometry data in pseudophakic eyes to achieve postoperative emmetropia. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. [Copyright &y& Elsevier]

The purpose of this study was to create a theoretical model of the eye based on a comparison of the real spherical equivalent of the eye and the calculated value of the axial refraction. The main contribution of this model is that it enables calculation of the equatorial plane of the lens for accurate assessment of the IOL position for a spherical eye model. The Gullstrand model of the eye was used as the source eye model and this was modified for the purposes of this study. The axial refraction of the final model of the eye was compared with the spherical equivalent. The accuracy of the developed model was statistically confirmed using statistic tests. Individual calculation of the axial refraction using it shows that IOL calculation is possible without any general statistical presumptions. It permits the calculation of variables with an accuracy accepted by inferential statistics. The accuracy of this theoretical eye model however, is limited by extreme values of variables -- an extreme value provides a less accurate result. [ABSTRACT FROM AUTHOR]

Purpose: To audit intraocular lens (IOL) power predictions for cataract surgery in extreme hyperopia and to compare the accuracy across different biometry formulae and IOL types.Design: A retrospective analysis of 76 eyes from 56 patients undergoing cataract surgery with IOLs ranging in power from 30 to 35 diopters (D).Methods: Axial lengths, corneal powers and anterior chamber depths were measured with ultrasound or optical methods, and the IOLMaster (Carl Zeiss Meditech, Inc, Dublin, California, USA) software was used to predict the refractive outcome for each IOL used. Differences between the predicted and actual postoperative refraction were then analyzed for each formula.Results: In practice, 55% of patients were within +/-1.0 D of the refraction predicted by their surgeon. In theory, the Haigis formula would have given the smallest mean refractive error (+0.51 +/- 0.12 D), followed by the Hoffer Q (-0.70 +/- 0.14 D), Holladay 1 (-1.11 +/- 0.13 D), and SRK/T formulae (-1.45 +/- 0.14 D). The Haigis formula overpredicted the lens power required, which would have generated a myopic result. The other formulae underpredicted the lens power required and would have generated a hyperopic result. There was a significant difference between lens designs: the Haigis was more accurate for open-loop, whereas the Hoffer Q was more accurate for plate-haptic lenses. The anterior chamber depth measurement could also be used to predict changes in intraocular pressure after surgery.Conclusion: This represents the largest published series to date of biometry predictions for cataract surgery in extreme hyperopia and confirms the Haigis formula to be the most accurate. A consistent difference between open-loop and plate-haptic lenses suggests that haptic design may influence the effective lens position in very small eyes. We further propose a simple formula to optimize the Haigis and Hoffer Q formulae in patients with extreme hyperopia. [ABSTRACT FROM AUTHOR]

Purpose: To examine the contribution of anterior chamber depth (ACD), lens thickness (LT), and white-to-white (WTW) measurements to intraocular lens (IOL) power calculations using the Barrett Universal II (BUII) formula. Methods: Measurements taken with the IOLMaster 700 (Carl Zeiss, Meditec AG, Jena, Germany) swept-source biometry of 501 right eyes of 501 consecutive patients undergoing cataract extraction surgery between January 2019 and March 2020 were reviewed. IOL power was calculated using the BUII formula, first through the inclusion of all measured variables and then by using partial biometry data. For each calculation method, the IOL power targeting emmetropia was recorded and compared for the whole cohort and stratified by axial length (AL) of the measured eye. Results: The mean IOL power calculated for the entire cohort using all available parameters was 19.50 ± 5.11 diopters (D). When comparing it to the results obtained by partial biometry data, the mean absolute difference ranged from 0.05 to 0.14 D; p < 0.001. The optional variables (ACD, LT, WTW) had the least effect in long eyes (AL ≥ 26 mm; mean absolute difference ranging from 0.02 to 0.07 D; p < 0.001), while the greatest effect in short eyes (AL ≤ 22 mm; mean absolute difference from 0.10 to 0.21 D; p < 0.001). The percentage of eyes with a mean absolute IOL dioptric power difference more than 0.25 D was the highest (32.0%) among the short AL group when using AL and keratometry values only. Conclusions: Using partial biometry data, the BUII formula in small eyes (AL ≤ 22 mm) resulted in a clinically significant difference in the calculated IOL power compared to the full biometry data. In contrast, the contribution of the optional parameters to the calculated IOL power was of little clinical importance in eyes with AL longer than 22 mm. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of pupil size on ocular biometric results. Materials and Methods: Pupil size in photopic conditions and axial lenght of patients who were diagnosed to have cataract in routine ophthalmological examination were measured and emmetropic intraocular lens power was calculated by SRK-T formula. This was followed by administration of tropicamide 0.5% and phenylephrine HCl 2.5% eye drops. Pupillary size, axial lenght measurements and emmetropic intraocular lens power calculation were repeated after 45 minutes. Results: Hundred and seventy five eyes of 127 patients aging between 41 and 89 (65.4±9.9, mean±st deviation) were enrolled. History of diabetes in 23 patients and pseudoexfoliation in 4 patients were evident. Pupil size in photopic conditions and following dilation were 3.1±0.9 and 7.2±0.9 mm, respectively. Axial lenght measurement was 23.6±1.0 mm before and 23.6±0.9 mm after pupillary dilation. The difference was not statistically significant (p=0.93, 95% confidence interval -0.032-0.035). Biometric measurements were 20.6±2.5 diopters in photopic conditions and 20.6±2.4 diopters when the pupil was dilated. Also, the difference was not statistically significant (p= 0.91, 95% confidence interval -0.103-0.091). Patient age, diabetes and pseudoexfoliation did not significantly affect the pupillary size and axial lenght measurements (p>0.05). Conclusion: Pupil size was found to effect axial lenght and biometric measurements slightly but not significantly. Larger groups, that concern postoperative refractive changes as well, could reveal more significant results. [ABSTRACT FROM AUTHOR]