Median absolute error and interquartile range as criteria of success against the percentage of eyes within a refractive target in IOL surgery

Object Sagittal spinopelvic imbalance is a major contributor to pain and disability for patients with adult spinal deformity (ASD). Preoperative planning is essential for pedicle subtraction osteotomy (PSO) candidates; however, current methods are often inaccurate because no formula to date predicts both postoperative sagittal balance and pelvic alignment. The authors of this study aimed to evaluate the accuracy of 2 novel formulas in predicting postoperative spinopelvic alignment after PSO. Methods This study is a multicenter retrospective consecutive PSO case series. Adults with spinal deformity (> 21 years old) who were treated with a single-level lumbar PSO for sagittal imbalance were evaluated. All patients underwent preoperative and a minimum of 6-month postoperative radiography. Two novel formulas were used to predict the postoperative spinopelvic alignment. The results predicted by the formulas were then compared with the actual postoperative radiographic values, and the formulas' ability to identify successful (sagittal vertical axis [SVA] ≤ 50 mm and pelvic tilt [PT] ≤ 25°) and unsuccessful (SVA > 50 mm or PT > 25°) outcomes was evaluated. Results Ninety-nine patients met inclusion criteria. The median absolute error between the predicted and actual PT was 4.1° (interquartile range 2.0°–6.4°). The median absolute error between the predicted and actual SVA was 27 mm (interquartile range 11–47 mm). Forty-one of 54 patients with a formula that predicted a successful outcome had a successful outcome as shown by radiography (positive predictive value = 0.76). Forty-four of 45 patients with a formula that predicted an unsuccessful outcome had an unsuccessful outcome as shown by radiography (negative predictive value = 0.98). Conclusions The spinopelvic alignment formulas were accurate when predicting unsuccessful outcomes but less reliable when predicting successful outcomes. The preoperative surgical plan should be altered if an unsuccessful result is predicted. However, even after obtaining a predicted successful outcome, surgeons should ensure that the predicted values are not too close to unsuccessful values and should identify other variables that may affect alignment. In the near future, it is anticipated that the use of these formulas will lead to better surgical planning and improved outcomes for patients with complex ASD.

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

British Journal of Ophthalmology ◽

10.1136/bjophthalmol-2020-315882 ◽

2020 ◽

pp. bjophthalmol-2020-315882

Author(s):

Veronika Röggla ◽

Achim Langenbucher ◽

Christina Leydolt ◽

Daniel Schartmüller ◽

Luca Schwarzenbacher ◽

...

Keyword(s):

Axial Length ◽

Prediction Error ◽

Absolute Error ◽

Power Calculation ◽

Corneal Power ◽

Biometric Parameters ◽

Iol Power Calculation ◽

Iol Power ◽

Median Absolute Error ◽

Axial Eye Length

AimsTo provide clinical guidance on the use of intraocular lens (IOL) power calculation formulas according to the biometric parameters.Methods611 eyes that underwent cataract surgery were retrospectively analysed in subgroups according to the axial length (AL) and corneal power (K). The predicted residual refractive error was calculated and compared to evaluate the accuracy of the following formulas: Haigis, Hoffer Q, Holladay 1 and SRK/T. Furthermore, the percentages of eyes with ≤±0.25, ≤±0.5 and 1 dioptres (D) of the prediction error were recorded.ResultsThe Haigis formula showed the highest percentage of cases with ≤0.5 D in eyes with a short AL and steep K (90%), average AL and steep cornea (73.2%) but also in long eyes with a flat and average K (65% and 72.7%, respectively). The Hoffer Q formula delivered the lowest median absolute error (MedAE) in short eyes with an average K (0.30 D) and Holladay 1 in short eyes with a steep K (Holladay 1 0.24 D). SRK/T presented the highest percentage of cases with ≤0.5 D in average long eyes with a flat and average K (80.5% and 68.1%, respectively) and the lowest MedAE in long eyes with an average K (0.29 D).ConclusionOverall, the Haigis formula shows accurate results in most subgroups. However, attention must be paid to the axial eye length as well as the corneal power when choosing the appropriate formula to calculate an IOL power, especially in eyes with an unusual biometry.

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Comparison of using Galilei Dual Scheimpflug Analyzer G4 and Barrett formula in predicting low cylinder preoperatively for cataract surgeries

European Journal of Ophthalmology ◽

10.1177/1120672119866068 ◽

2019 ◽

Vol 30 (6) ◽

pp. 1320-1327

Author(s):

Yi-Ju Ho ◽

Chi-Chin Sun ◽

Jiahn-Shing Lee ◽

Ken-Kuo Lin ◽

Chiun-Ho Hou

Keyword(s):

Cataract Surgery ◽

Absolute Error ◽

Corneal Astigmatism ◽

Intraocular Lens Implantation ◽

Surgically Induced Astigmatism ◽

Lens Implantation ◽

Induced Astigmatism ◽

Median Absolute Error ◽

The Difference ◽

Surgically Induced

Purpose: To compare corneal astigmatism estimation from Barrett toric calculator, with measurement from Galilei Dual Scheimpflug Analyzer G4 in low corneal cylinder patients. Methods: Preoperative corneal astigmatism was measured using Auto Kerato-Refractometer (AutoKM), IOL Master, and Galilei G4 (combined Placido-dual Scheimpflug analyzer) and was processed by Barrett toric calculator with measurements obtained from Auto Kerato-Refractometer and from IOL Master. A total of 42 eyes undergoing cataract surgery with nontoric intraocular lens implantation were included. Corneal astigmatism was calculated based on manifest refractive astigmatism with implications of surgically induced astigmatism. Errors in predicted residual astigmatism were calculated by the difference between postoperative manifest cylindrical refractive error and preoperative corneal cylinder using vector analysis. Results: Centroid error in predicted residual astigmatism was with-the-rule 0.36 D for AutoKM and 0.48 D for IOL Master, was lower at 0.24 D for the Barrett–IOL Master, and was lowest at 0.21 D for the Barrett–AutoKM ( p < .001). The Galilei G4 demonstrated the highest centroid error for SimK (0.53 D) and lower for total corneal power (0.49 D). The Barrett toric calculator obtained the lowest median absolute error in predicted residual astigmatism for AutoKM (0.43 D) and IOL Master (0.54 D). The Barrett–IOL Master demonstrated that 61% and 76% of eyes were within 0.50 and 0.75 D of the predicted residual astigmatism, respectively. Conclusion: The Barrett–IOL Master had more accurate prediction of residual astigmatism for low astigmatism eyes before cataract surgery compared to Galilei Dual Scheimpflug Analyzer G4 in this study.

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Reducing Errors in Velocity–Azimuth Display (VAD) Wind and Deformation Retrievals from Airborne Doppler Radars in Convective Environments

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-20-0034.1 ◽

2020 ◽

Vol 37 (12) ◽

pp. 2251-2266

Author(s):

Charles N. Helms ◽

Matthew L. Walker McLinden ◽

Gerald M. Heymsfield ◽

Stephen R. Guimond

Keyword(s):

Wind Field ◽

Doppler Radar ◽

Weighting Function ◽

Deep Convection ◽

Absolute Error ◽

Doppler Velocity ◽

Wind Fields ◽

Time Data ◽

Single Antenna ◽

Median Absolute Error

AbstractThe present study describes methods to reduce the uncertainty of velocity–azimuth display (VAD) wind and deformation retrievals from downward-pointing, conically scanning, airborne Doppler radars. These retrievals have important applications in data assimilation and real-time data processing. Several error sources for VAD retrievals are considered here, including violations to the underlying wind field assumptions, Doppler velocity noise, data gaps, temporal variability, and the spatial weighting function of the VAD retrieval. Specific to airborne VAD retrievals, we also consider errors produced due to the radar scans occurring while the instrument platform is in motion. While VAD retrievals are typically performed using data from a single antenna revolution, other strategies for selecting data can be used to reduce retrieval errors. Four such data selection strategies for airborne VAD retrievals are evaluated here with respect to their effects on the errors. These methods are evaluated using the second hurricane nature run numerical simulation, analytic wind fields, and observed Doppler radar radial velocities. The proposed methods are shown to reduce the median absolute error of the VAD wind retrievals, especially in the vicinity of deep convection embedded in stratiform precipitation. The median absolute error due to wind field assumption violations for the along-track and for the across-track wind is reduced from 0.36 to 0.08 m s−1 and from 0.35 to 0.24 m s−1, respectively. Although the study focuses on Doppler radars, the results are equally applicable to conically scanning Doppler lidars as well.

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Comparison of Two Toric IOL Calculation Methods

Journal of Ophthalmology ◽

10.1155/2018/2840246 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 3

Author(s):

C. Kern ◽

K. Kortüm ◽

M. Müller ◽

A. Kampik ◽

S. Priglinger ◽

...

Keyword(s):

Intraocular Lens ◽

Absolute Error ◽

Spherical Equivalent ◽

Calculation Methods ◽

Refractive Outcome ◽

Toric Intraocular Lens ◽

Iol Calculation ◽

Median Absolute Error ◽

Lens Power ◽

Posterior Corneal Astigmatism

Purpose. To compare two calculators for toric intraocular lens (IOL) calculation and to evaluate the prediction of refractive outcome. Methods. Sixty-four eyes of forty-five patients underwent cataract surgery followed by implantation of a toric intraocular lens (Zeiss Torbi 709 M) calculated by a standard industry calculator using front keratometry values. Prediction error, median absolute error, and refractive astigmatism error were evaluated for the standard calculator. The predicted postoperative refraction and toric lens power values were evaluated and compared after postoperative recalculation using the Barrett calculator. Results. We observed a significant undercorrection in the spherical equivalent (0.19 D) by using a standard calculator (p≤0.05). According to the Baylor nomogram and the refractive influence of posterior corneal astigmatism (PCA), undercorrection of the cylinder was lower for patients with WTR astigmatism, because of the tendency of overcorrection. An advantage of less residual postoperative SE, sphere, and cylinder for the Barrett calculator was observed when retrospectively comparing the calculated predicted postoperative refraction between calculators (p≤0.01). Conclusion. Consideration of only corneal front keratometric values for toric lens calculation may lead to postoperative undercorrection of astigmatism. The prediction of postoperative refractive outcome can be improved by using appropriate methods of adjustment in order to take PCA into account.

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Estimating Anesthesia and Surgical Procedure Times from Medicare Anesthesia Claims

Anesthesiology ◽

10.1097/00000542-200702000-00024 ◽

2007 ◽

Vol 106 (2) ◽

pp. 346-355 ◽

Cited By ~ 32

Author(s):

Jeffrey H. Silber ◽

Paul R. Rosenbaum ◽

Xuemei Zhang ◽

Orit Even-Shoshan

Keyword(s):

Rank Correlation ◽

Absolute Error ◽

Anesthesia Service ◽

Orthopedic Surgical Procedures ◽

Medicare Part B ◽

Median Absolute Error ◽

The Individual ◽

Larger Sample ◽

Procedure Type ◽

Individual Hospital

Background Procedure times are important variables that often are included in studies of quality and efficiency. However, due to the need for costly chart review, most studies are limited to single-institution analyses. In this article, the authors describe how well the anesthesia claim from Medicare can estimate chart times. Methods The authors abstracted information on time of induction and entrance to the recovery room ("anesthesia chart time") from the charts of 1,931 patients who underwent general and orthopedic surgical procedures in Pennsylvania. The authors then merged the associated bills from claims data supplied from Medicare (Part B data) that included a variable denoting the time in minutes for the anesthesia service. The authors also investigated the time from incision to closure ("surgical chart time") on a subset of 1,888 patients. Results Anesthesia claim time from Medicare was highly predictive of anesthesia chart time (Kendall's rank correlation tau = 0.85, P < 0.0001, median absolute error = 5.1 min) but somewhat less predictive of surgical chart time (Kendall's tau = 0.73, P < 0.0001, median absolute error = 13.8 min). When predicting chart time from Medicare bills, variables reflecting procedure type, comorbidities, and hospital type did not significantly improve the prediction, suggesting that errors in predicting the chart time from the anesthesia bill time are not related to these factors; however, the individual hospital did have some influence on these estimates. Conclusions Anesthesia chart time can be well estimated using Medicare claims, thereby facilitating studies with vastly larger sample sizes and much lower costs of data collection.

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Corneal topographic ring vs zone in trifocal IOL calculation

Modern technologies in ophtalmology ◽

10.25276/2312-4911-2021-2-184-186 ◽

2021 ◽

pp. 184-186

Author(s):

A.D. Loginova ◽

◽

S.V. Shukhaev ◽

S.S. Kudlakhmedov ◽

E.V. Boiko ◽

...

Keyword(s):

Power Distribution ◽

Mean Absolute Error ◽

Absolute Error ◽

Accurate Calculation ◽

Iol Implantation ◽

Topographic Data ◽

Trifocal Iol ◽

Iol Calculation ◽

Km Value ◽

Median Absolute Error

Purpose. To compare the results of trifocal IOL calculation using various corneal topographic data (ring and zone). Methods. This retrospective study involved 35 patients (40 eyes), underwent cataract surgery (FLACS) with trifocal IOL implantation (AcrySof IQ PanOptix). The calculation was performed using IOL-Master 500 according to 4 formulas (Haigis, HofferQ, Holladay 1, SRK / T) and Tomey OA-2000 according to 2 formulas (Barrett II Universal, Olsen). Topographic values included Km collected from Pentacam HR Power Distribution Apex map with diameter of 3.0 and 5.0 mm on a ring and zone. Predicted and actual refraction were compared after surgery. Results. Mean Km value on 3 mm zone and ring was: 42.75±1,46 D and 42.91±1.43 D, respectively (p<0.0001). Mean Km value on 5 mm zone and ring was: 43.09±1.5 D and 43.55±1.48 D, respectively (p<0.0001). According to 6 formulas Mean Absolute Error (MAE) calculated using 3 mm zone data was significantly less then on 3mm ring: 0.3± 0.28; 0.48±0.3 and Median Absolute Error (MedAE) was 0.225 (0.3); 0.465 (0.397) respectively (p<0.01). The same data were obtained on 5mm zone and ring: MAE was 0.29±0.28; 0.35±0.29 and MedAE amounted to 0.225 (0.3); 0.29 (0.38) respectively (p=0.02). Conclusion. Mean Km value on Power Distribution Apex map according to ring is significantly greater then according to zone. 1) Predicted refraction using corneal topographic ring data deviates towards hyperopia relative to the actual postoperative refraction. 2) The use of topographic data on zone allows to obtain more accurate calculation of trifocal IOL than when using the data on the ring. Key words: IOL calculation, Trifocal IOL, corneal topography.

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T2 formula in a highly myopic population, comparison with other methods and description of an improved approach for estimating corneal height

BMC Ophthalmology ◽

10.1186/s12886-019-1226-7 ◽

2019 ◽

Vol 19 (1) ◽

Author(s):

Carlos Alberto Idrobo-Robalino ◽

Gisella Santaella ◽

Ángela María Gutiérrez

Keyword(s):

Mean Absolute Error ◽

Estimation Method ◽

Case Series ◽

Crystalline Lens ◽

Absolute Error ◽

Prediction Errors ◽

Retrospective Case ◽

Population Comparison ◽

Median Absolute Error ◽

Optical Biometer

Abstract Background To determine the accuracy of the T2 formula as applied to highly myopic eyes, to compare the T2 formula to the SRK/T and Holladay 1 formulas, and to describe possible ways to improve the estimation of corneal height and prediction error in two settings, the Hadassah Hospital, Ophthalmology Department, Jerusalem, Israel and Clínica Barraquer, Bogotá, Colombia. Methods In this retrospective case series, optical biometer measurements were taken for 63 highly myopic patients (> 25 mm) undergoing uneventful crystalline lens phacoemulsification and insertion of an acrylic intraocular lens. Prediction errors were obtained, with estimations of ±0.50 D, ± 1.00 D, and greater than ±2.00 D. A method to improve the corneal height calculation is described. Results The SRK/T formula (mean absolute error [MAE] = 0.418; median absolute error [MedAE] = 0.352) was the most accurate, followed by the T2 (MAE = 0.435; MedAE = 0.381) and Holladay 1 (MAE = 0.455; MedAE = 0.389) formulas. Both the SRK/T and T2 formulas overestimated corneal height, but values were higher with the T2 formula. Corneal height was more precisely estimated using an alternative method that, when combined with axial length optimization, resulted in lower MAE (0.425) and MedAE (0.365) values than when applying the T2 formula alone. Conclusions The T2 formula seems to be less accurate than the SRK/T formula in highly myopic eyes. An improved corneal height estimation method is described for the the T2 formula.

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Lenstar LS 900 versus Pentacam-AXL: analysis of refractive outcomes and predicted refraction

Scientific Reports ◽

10.1038/s41598-021-81146-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Henrique Aragão Arruda ◽

Joana M. Pereira ◽

Arminda Neves ◽

Maria João Vieira ◽

Joana Martins ◽

...

Keyword(s):

Refractive Error ◽

Prediction Error ◽

Mean Absolute Error ◽

Absolute Error ◽

Spherical Equivalent ◽

Refractive Outcomes ◽

Iol Calculation ◽

Median Absolute Error ◽

The Difference ◽

Mean Prediction Error

AbstractAnalysis of refractive outcomes, using biometry data collected with a new biometer (Pentacam-AXL, OCULUS, Germany) and a reference biometer (Lenstar LS 900, HAAG-STREIT AG, Switzerland), in order to assess differences in the predicted and actual refraction using different formulas. Prospective, institutional study, in which intraocular lens (IOL) calculation was performed using the Haigis, SRK/T and Hoffer Q formulas with the two systems in patients undergoing cataract surgery between November 2016 and August 2017. Four to 6 weeks after surgery, the spherical equivalent (SE) was derived from objective refraction. Mean prediction error (PE), mean absolute error (MAE) and the median absolute error (MedAE) were calculated. The percentage of eyes within ± 0.25, ± 0.50, ± 1.00, and ± 2.00 D of MAE was determined. 104 eyes from 76 patients, 35 males (46.1%), underwent uneventful phacoemulsification with IOL implantation. Mean SE after surgery was − 0.29 ± 0.46 D. Mean prediction error (PE) using the SRK/T, Haigis and Hoffer Q formulas with the Lenstar was significantly different (p > 0.0001) from PE calculated with the Pentacam in all three formulas. Percentage of eyes within ± 0.25 D MAE were larger with the Lenstar device, using all three formulas. The difference between the actual refractive error and the predicted refractive error is consistently lower when using Lenstar. The Pentacam-AXL user should be alert to the critical necessity of constant optimization in order to obtain optimal refractive results.

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A machine vision based frailty index for mice

10.1101/2021.09.27.462066 ◽

2021 ◽

Author(s):

Leinani E. Hession ◽

Gautam S. Sabnis ◽

Gary A. Churchill ◽

Vivek Kumar

Keyword(s):

Health Status ◽

Open Field ◽

Large Scale ◽

Frailty Index ◽

Absolute Error ◽

Video Data ◽

Biological Aging ◽

Chronological Aging ◽

Field Assay ◽

Median Absolute Error

1AbstractChronological aging is uniform, but biological aging is heterogeneous. Clinically, this heterogeneity manifests itself in health status and mortality, and it distinguishes healthy from unhealthy aging. Clinical frailty indexes (FIs) serve as an important tool in gerontology to capture health status. FIs have been adapted for use in mice and are an effective predictor of mortality risk. To accelerate our understanding of biological aging, high-throughput approaches to pre-clinical studies are necessary. Currently, however, mouse frailty indexing is manual and relies on trained scorers, which imposes limits on scalability and reliability. Here, we introduce a machine learning based visual frailty index (vFI) for mice that operates on video data from an open field assay. We generate a large mouse FI datasets comprising 256 males and 195 females. From video data on these same mice, we use neural networks to extract morphometric, gait, and other behavioral features that correlate with manual FI score and age. We use these features to train a regression model that accurately predicts frailty within 1.03 ± 0.08 (3.9% ± 0.3%) of the pre-normalized FI score in terms of median absolute error. We show that features of biological aging are encoded in open-field video data and can be used to construct a vFI that can complement or replace current manual FI methods. We use the vFI data to examine sex-specific aspects of aging in mice. This vFI provides increased accuracy, reproducibility, and scalability, that will enable large scale mechanistic and interventional studies of aging in mice.

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