scholarly journals Intraocular Lens Power Calculation According to the Difference between Anterior and Total Keratometry Using Scheimpflug Imaging

2021 ◽  
Vol 62 (9) ◽  
pp. 1181-1188
Author(s):  
Joong Hee Kim ◽  
Kyong Jin Cho ◽  
Ho Seok Chung
Keyword(s):  
Regression Analysis ◽  
Absolute Error ◽  
Power Calculation ◽  
Intraocular Lens Power Calculation ◽  
Refractive Power ◽  
Simple Regression Analysis ◽  
The Absolute ◽  
The Difference ◽  
Lens Power ◽  
Simple Regression

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.

scholarly journals Intraocular lens power calculation for plus and minus lenses in high myopia using partial coherence interferometry

2021 ◽  
Author(s):  
Matthias Fuest ◽  
Niklas Plange ◽  
David Kuerten ◽  
Hannah Schellhase ◽  
Babac A. E. Mazinani ◽  
...  
Keyword(s):  
Axial Length ◽  
Absolute Error ◽  
Intraocular Lenses ◽  
Partial Coherence ◽  
Power Calculation ◽  
Partial Coherence Interferometry ◽  
Intraocular Lens Power Calculation ◽  
Hyperopic Shift ◽  
Lens Power ◽  
Lens Power Calculation

Abstract Purpose We assessed the accuracy of lens power calculation in highly myopic patients implanting plus and minus intraocular lenses (IOL). Methods We included 58 consecutive, myopic eyes with an axial length (AL) > 26.0 mm, undergoing phacoemulsification and IOL implantation following biometry using the IOLMaster 500. For lens power calculation, the Haigis formula was used in all cases. For comparison, refraction was back-calculated using the Barrett Universal II (Barrett), Holladay I, Hill-RBF (RBF) and SRK/T formulae. Results The mean axial length was 30.17 ± 2.67 mm. Barrett (80%), Haigis (87%) and RBF (82%) showed comparable numbers of IOLs within 1 diopter (D) of target refraction. Visual acuity (BSCVA) improved (p < 0.001) from 0.60 ± 0.35 to 0.29 ± 0.29 logMAR (> 28-days postsurgery). The median absolute error (MedAE) of Barrett 0.49 D, Haigis 0.38, RBF 0.44 and SRK/T 0.44 did not differ. The MedAE of Haigis was significantly smaller than Holladay (0.75 D; p = 0.01). All median postoperative refractive errors (MedRE) differed significantly with the exception of Haigis to SRK/T (p = 0.6): Barrett − 0.33 D, Haigis 0.25, Holladay 0.63, RBF 0.04 and SRK/T 0.13. Barrett, Haigis, Holladay and RBF showed a tendency for higher MedAEs in their minus compared to plus IOLs, which only reached significance for SRK/T (p = 0.001). Barrett (p < 0.001) and RBF (p = 0.04) showed myopic, SRK/T (p = 002) a hyperopic shift in their minus IOLs. Conclusions In highly myopic patients, the accuracies of Barrett, Haigis and RBF were comparable with a tendency for higher MedAEs in minus IOLs. Barrett and RBF showed myopic, SRK/T a hyperopic shift in their minus IOLs.

Methodologies Used to Analyze Collision Experience Associated with Speed Limit Changes on Selected California Highways

2002 ◽  
Vol 1784 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Curt B. Haselton ◽  
A. Reed Gibby ◽  
Thomas C. Ferrara
Keyword(s):  
Regression Analysis ◽  
Analysis Of Variance ◽  
Rate Increase ◽  
Comparison Group ◽  
Speed Limit ◽  
Observational Method ◽  
Collision Rate ◽  
Simple Regression Analysis ◽  
The Difference ◽  
Simple Regression

Three methodologies are used and compared to determine whether there has been a statistically significant change in traffic collisions (total, fatal, fatal plus injury, wet pavement, and nighttime) due to recent speed limit increases on California state highways. The three methods compared were simple regression, analysis of variance (ANOVA), and an observational before–after study developed by Ezra Hauer. Both collision counts and rates were studied for early 1996 speed limit increases from 55 to 65 mph, and from 65 to 70 mph. A comparison group of highways that remained at 55 mph was also studied. The simple regression methodology did not detect nearly as many statistically significant increases as did the ANOVA and Hauer observational before–after methodologies. The latter two methods revealed very similar results, especially for statistically significant increases in total and fatal collision rates and counts. These methodologies also revealed a significant increase in nighttime collisions for the 55–65 mph group. The difference was that the observational method detected only a marginally significant increase with total collisions for the 65–70 mph group. Also, the ANOVA indicated that the fatality collision rate increase for the 65–70 mph group was marginally significant.

scholarly journals Accuracy of Intraocular Lens Power Calculation Formulas for Highly Myopic Eyes

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Yichi Zhang ◽  
Xiao Ying Liang ◽  
Shu Liu ◽  
Jacky W. Y. Lee ◽  
Srinivasan Bhaskar ◽  
...  
Keyword(s):  
Intraocular Lens ◽  
Absolute Error ◽  
Power Calculation ◽  
Prediction Errors ◽  
Intraocular Lens Power Calculation ◽  
Iol Power Calculation ◽  
Predictive Error ◽  
Intraocular Lens Power ◽  
Iol Power ◽  
Lens Power

Purpose.To evaluate and compare the accuracy of different intraocular lens (IOL) power calculation formulas for eyes with an axial length (AL) greater than 26.00 mm.Methods.This study reviewed 407 eyes of 219 patients with AL longer than 26.0 mm. The refractive prediction errors of IOL power calculation formulas (SRK/T, Haigis, Holladay, Hoffer Q, and Barrett Universal II) using User Group for Laser Interference Biometry (ULIB) constants were evaluated and compared.Results.One hundred seventy-one eyes were enrolled. The Barrett Universal II formula had the lowest mean absolute error (MAE) and SRK/T and Haigis had similar MAE, and the statistical highest MAE were seen with the Holladay and Hoffer Q formulas. The interquartile range of the Barrett Universal II formula was also the lowest among all the formulas. The Barrett Universal II formulas yielded the highest percentage of eyes within ±1.0 D and ±0.5 D of the target refraction in this study (97.24% and 79.56%, resp.).Conclusions.Barrett Universal II formula produced the lowest predictive error and the least variable predictive error compared with the SRK/T, Haigis, Holladay, and Hoffer Q formulas. For high myopic eyes, the Barrett Universal II formula may be a more suitable choice.

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

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Chong Chen ◽  
Xian Xu ◽  
Yuyu Miao ◽  
Gaoxin Zheng ◽  
Yong Sun ◽  
...  
Keyword(s):  
Intraocular Lens ◽  
Axial Length ◽  
Retrospective Chart Review ◽  
Absolute Error ◽  
Intraocular Lenses ◽  
Chinese Patients ◽  
Power Calculation ◽  
Intraocular Lens Power Calculation ◽  
Intraocular Lens Power ◽  
Lens Power

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

scholarly journals Nationwide multicentre comparison of preoperative biometry and predictability of cataract surgery in Japan

2021 ◽  
pp. bjophthalmol-2021-318825
Author(s):  
Kazutaka Kamiya ◽  
Ken Hayashi ◽  
Mao Tanabe ◽  
Hitoshi Tabuchi ◽  
Masaki Sato ◽  
...  
Keyword(s):  
Cataract Surgery ◽  
Prediction Error ◽  
Corneal Thickness ◽  
Anterior Chamber Depth ◽  
Absolute Error ◽  
Power Calculation ◽  
Clinical Trial Registry ◽  
Biometric Data ◽  
Intraocular Lens Power Calculation ◽  
The Absolute

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 (p<0.001), lens thickness (p<0.001) and central corneal thickness (p<0.001), except for mean keratometry (p=0.587) and corneal astigmatism (p=0.304), among the 12 surgical sites. The prediction error using the Sanders-Retzlaff-Kraff/Theoretical (SRK/T formula was significantly more hyperopic than that using the Barrett Universal II formula (paired t-test, p<0.001). The absolute error using the SRK/T formula was significantly larger than that using the Barrett Universal II formula (p=0.016). The prediction error using the SRK/T formula was significantly more hyperopic than that using the Barrett Universal II formula at 10 of 12 institutions, but significantly more myopic at one institution. The absolute error using the SRK/T formula was significantly larger than that using the Barrett Universal II formula at 4 of 12 institutions but significantly smaller at two institutions.ConclusionsRegional 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.

scholarly journals Accuracy of Intraocular Lens Power Calculation Using Anterior Chamber Depth from Two Devices with Barrett Universal II Formula

2019 ◽  
Vol 2019 ◽  
pp. 1-5
Author(s):  
Hannah Muniz Castro ◽  
Audrey X. Tai ◽  
Samuel J. Sampson ◽  
Matthew Wade ◽  
Marjan Farid ◽  
...  
Keyword(s):  
Anterior Chamber ◽  
Anterior Chamber Depth ◽  
Absolute Error ◽  
Power Calculation ◽  
Intraocular Lens Power Calculation ◽  
Iol Power Calculation ◽  
Significant Difference ◽  
Iol Power ◽  
Retrospective Comparative Study ◽  
Lens Power

Purpose. To compare the preoperative measurements of the anterior chamber depth (ACD) by the IOLMaster and Catalys; additionally, to compare the accuracy of the IOL power calculated by the Barrett Universal II formula using the two different measurements. Setting. University of California, Irvine, Gavin Herbert Eye Institute in Irvine, California. Design. Retrospective comparative study. Methods. This study included 144 eyes of 90 patients with a mean age of 72.0 years (range 40.8 to 92.1 years) that underwent femtosecond laser-assisted cataract surgery using Catalys. Preoperative measurements of ACD were taken by the IOLMaster and Catalys. Manifest refraction and refractive spherical equivalent were measured 1 month postoperatively. Expected refractive results were compared with actual postoperative refractive results. Results. The correlation between the ACD values from the two devices was good (r = 0.80). The Catalys ACD measurements yielded a larger ACD compared to the IOLMaster, with a mean difference of 0.22 mm (P<0.0001). The correlation between the postoperative and predicted RSE of the implanted IOL power was excellent (r = 0.96). There was no statistically significant difference between the mean absolute error derived from the IOLMaster, 0.37 diopter (D) ± 0.34 (SD), and the Catalys, 0.37 ± 0.35 D (P=0.50). Conclusions. The Catalys biometry yielded a significantly larger ACD value than the IOLMaster. This difference in ACD value, however, did not reflect in a statistically significant difference in IOL power calculation and refractive prediction error using the Barrett Universal II Formula.

scholarly journals Strategi Orientasi Pasar Dalam Menciptakan Keunggulan Bersaing

2019 ◽  
Vol 17 (2) ◽  
pp. 79
Author(s):  
Nurrisbayanti Ruhiyantina ◽  
Lili Adi Wibowo ◽  
Bambang Widjajanta
Keyword(s):  
Regression Analysis ◽  
Data Analysis ◽  
Competitive Advantage ◽  
Market Orientation ◽  
Measurement Instrument ◽  
Data Analysis Technique ◽  
Analysis Technique ◽  
Simple Regression Analysis ◽  
The Difference ◽  
Simple Regression

This research was conducted to see how much influence market orientation has on competitive advantage. This type of research is descriptive and verification with samples taken as many as 20 respondents who meet the criteria set out in the study. The data analysis technique in this study uses simple regression. Based on the results of the study using simple regression analysis, the results show that market orientation has a significant effect on competitive advantage. The difference between this research and other research lies in the object of research, the measurement instrument used, the population and the sample of the study, and the results of the research. In this study using theories from journals and books, so the theory used is different.

scholarly journals Accuracy of intraocular lens power calculation in pediatric cataracts with less than a 20 mm axial length of the eye

2014 ◽  
Vol 6 (1) ◽  
pp. 56-64 ◽  
Author(s):  
Purushottam Joshi ◽  
Raman Mehta ◽  
Suma Ganesh
Keyword(s):  
Axial Length ◽  
Prediction Error ◽  
Power Calculation ◽  
Pediatric Cataract ◽  
Intraocular Lens Power Calculation ◽  
Iol Power Calculation ◽  
Intraocular Lens Power ◽  
Iol Power ◽  
The Absolute ◽  
Lens Power

Introduction: Selection of an appropriately-powered IOL is a complex issue, especially in eyes with an axial length of less than 20 mm in pediatric cataract. Objective: To assess the accuracy of IOL power calculation formulae in pediatric cataracts in eyes with an axial length of less than 20 mm. Materials and methods: The records of children less than 15 years old with congenital cataract who had undergone primary IOL implantation were analyzed. Main outcome measures: The variables studied were axial length, keratometric values and the prediction error. The data were analyzed for prediction error determination using the SRK II, SRK T, Holladay 1 and Hoffer Q IOL power calculation formulae. The formula that gave the best prediction error was identified. Results: Twenty-eight eyes of 19 children were included in the study. The absolute prediction error was found to be 1.84 ± 2.09 diopters (D) with SRK II, 2.93±3.55D with SRK T, 3.63±4.06D with Holladay 1, and 4.83±5.02D with Hoffer Q. The number of eyes with the absolute prediction error within 0.5 D was 6 (21.42%) with SRK II, 4 (14.28%) with SRK T, 1 (3.57%) with Holladay 1, and 3 (10.71%) with Hoffer Q. The absolute prediction error with SRK II formula was significantly better than that with other formulae (P < .001). The axial length influenced the absolute prediction error with Hoffer Q formula (P = 0.04). The mean keratometry influenced the prediction error with SRK T formula (P = 0.02), Holladay 1 formula (P = 0.02) and Hoffer Q formula (P = 0.02). Conclusion: Although the absolute prediction error tends to remain high with all the present IOL power calculation formulae, SRK II was the most predictable formula in this study. DOI: http://dx.doi.org/10.3126/nepjoph.v6i1.10773 Nepal J Ophthalmol 2014; 6 (2): 56-64

Intraocular lens power calculation in virgin eyes: Accuracy of the Barrett Universal II formula and a Ray tracing software

2021 ◽  
pp. 112067212110655
Author(s):  
Joaquim Fernández-Rosés ◽  
José Lamarca ◽  
David P. Piñero ◽  
Rafael I. Barraquer
Keyword(s):  
Ray Tracing ◽  
Intraocular Lens ◽  
Prediction Error ◽  
Pupil Diameter ◽  
Absolute Error ◽  
Power Calculation ◽  
Intraocular Lens Power Calculation ◽  
Intraocular Lens Power ◽  
Lens Power ◽  
Lens Power Calculation

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 < 0.01). A significant correlation between the prediction error of the Barrett Universal II formula and corneal diameter (r = 0.322, p = 0.002) and pupil diameter (r = 0.230, p = 0.033) was found. Also, a positive correlation between the prediction error of Sirius ray tracing and axial length ( p < 0.001) and pupil diameter ( p = 0.01) was found. 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.

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