A Validation of Supervised Deep Learning for Gait Analysis in the Cat

Gait analysis in cats and other animals is generally performed with custom-made or commercially developed software to track reflective markers placed on bony landmarks. This often involves costly motion tracking systems. However, deep learning, and in particular DeepLabCutTM (DLC), allows motion tracking without requiring placing reflective markers or an expensive system. The purpose of this study was to validate the accuracy of DLC for gait analysis in the adult cat by comparing results obtained with DLC and a custom-made software (Expresso) that has been used in several cat studies. Four intact adult cats performed tied-belt (both belts at same speed) and split-belt (belts operating at different speeds) locomotion at different speeds and left-right speed differences on a split-belt treadmill. We calculated several kinematic variables, such as step/stride lengths and joint angles from the estimates made by the two software and assessed the agreement between the two measurements using intraclass correlation coefficient or Lin’s concordance correlation coefficient as well as Pearson’s correlation coefficients. The results showed that DLC is at least as precise as Expresso with good to excellent agreement for all variables. Indeed, all 12 variables showed an agreement above 0.75, considered good, while nine showed an agreement above 0.9, considered excellent. Therefore, deep learning, specifically DLC, is valid for measuring kinematic variables during locomotion in cats, without requiring reflective markers and using a relatively low-cost system.

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Development and Relative Validity of a Semiquantitative Food Frequency Questionnaire to Estimate Dietary Intake among a Multi-Ethnic Population in the Malaysian Cohort Project

Nutrients ◽

10.3390/nu13041163 ◽

2021 ◽

Vol 13 (4) ◽

pp. 1163

Author(s):

Suzana Shahar ◽

Mohd Razif Shahril ◽

Noraidatulakma Abdullah ◽

Boekhtiar Borhanuddin ◽

Mohd Arman Kamaruddin ◽

...

Keyword(s):

Vitamin C ◽

Correlation Coefficient ◽

Food Frequency Questionnaire ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Weighted Kappa ◽

Dietary Intakes ◽

Food Frequency ◽

Relative Validity ◽

Spearman’S Correlation

Measuring dietary intakes in a multi-ethnic and multicultural setting, such as Malaysia, remains a challenge due to its diversity. This study aims to develop and evaluate the relative validity of an interviewer-administered food frequency questionnaire (FFQ) in assessing the habitual dietary exposure of The Malaysian Cohort (TMC) participants. We developed a nutrient database (with 203 items) based on various food consumption tables, and 803 participants were involved in this study. The output of the FFQ was then validated against three-day 24-h dietary recalls (n = 64). We assessed the relative validity and its agreement using various methods, such as Spearman’s correlation, weighed Kappa, intraclass correlation coefficient (ICC), and Bland–Altman analysis. Spearman’s correlation coefficient ranged from 0.24 (vitamin C) to 0.46 (carbohydrate), and almost all nutrients had correlation coefficients above 0.3, except for vitamin C and sodium. Intraclass correlation coefficients ranged from −0.01 (calcium) to 0.59 (carbohydrates), and weighted Kappa exceeded 0.4 for 50% of nutrients. In short, TMC’s FFQ appears to have good relative validity for the assessment of nutrient intake among its participants, as compared to the three-day 24-h dietary recalls. However, estimates for iron, vitamin A, and vitamin C should be interpreted with caution.

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Psychometric Properties of the MyotonPRO in Dementia Patients with Paratonia

Gerontology ◽

10.1159/000485462 ◽

2017 ◽

Vol 64 (4) ◽

pp. 401-412 ◽

Cited By ~ 5

Author(s):

Hans Drenth ◽

Sytse U. Zuidema ◽

Wim P. Krijnen ◽

Ivan Bautmans ◽

Cees van der Schans ◽

...

Keyword(s):

Psychometric Properties ◽

Correlation Coefficient ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Functional Mobility ◽

Future Research ◽

Minimal Detectable Change ◽

Muscle Properties ◽

Dementia Patients ◽

Longitudinal Outcome

Background: Paratonia is a distinctive form of hypertonia, causing loss of functional mobility in early stages of dementia to severe high muscle tone and pain in the late stages. For assessing and evaluating therapeutic interventions, objective instruments are required. Objective: Determine the psychometric properties of the MyotonPRO, a portable device that objectively measures muscle properties, in dementia patients with paratonia. Methods: Muscle properties were assessed with the MyotonPRO by 2 assessors within one session and repeated by the main researcher after 30 min and again after 6 months. Receiver operating characteristic curves were constructed for all MyotonPRO outcomes to discriminate between participants with (n = 70) and without paratonia (n = 82). In the participants with paratonia, correlation coefficients were established between the MyotonPRO outcomes and the Modified Ashworth Scale for paratonia (MAS-P) and muscle palpation. In participants with paratonia, reliability (intraclass correlation coefficient) and agreement values (standard error of measurement and minimal detectable change) were established. Longitudinal outcome from participants with paratonia throughout the study (n = 48) was used to establish the sensitivity for change (correlation coefficient) and responsiveness (minimal clinical important difference). Results: Included were 152 participants with dementia (mean [standard deviation] age of 83.5 [98.2]). The area under the curve ranged from 0.60 to 0.67 indicating the MyotonPRO is able to differentiate between participants with and without paratonia. The MyotonPRO explained 10-18% of the MAS-P score and 8-14% of the palpation score. Interclass correlation coefficients for interrater reliability ranged from 0.57 to 0.75 and from 0.54 to 0.71 for intrarater. The best agreement values were found for tone, elasticity, and stiffness. The change between baseline and 6 months in the MyotonPRO outcomes explained 8-13% of the change in the MAS-P scores. The minimal clinically important difference values were all smaller than the measurement error. Conclusion: The MyotonPRO is potentially applicable for cross-sectional studies between groups of paratonia patients and appears less suitable to measure intraindividual changes in paratonia. Because of the inherent variability in movement resistance in paratonia, the outcomes from the MyotonPRO should be interpreted with care; therefore, future research should focus on additional guidelines to increase the clinical interpretation and improving reproducibility.

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AB0798 IS THERE A REPRODUCIBILITY OF THE HISTOGRAM AND GRAY SCALE IN ECOEXTRUCTURAL DAMAGES IN RHEUMATOTOLOGICAL DISEASES?

Annals of the Rheumatic Diseases ◽

10.1136/annrheumdis-2021-eular.3269 ◽

2021 ◽

Vol 80 (Suppl 1) ◽

pp. 1423.2-1424

Author(s):

J. A. Mendonça ◽

I. Siste de Almeida Aoki ◽

C. C. Cavuto ◽

V. A. Leandro-Merhi ◽

J. L. B. D. Aquino

Keyword(s):

Correlation Coefficient ◽

Intraclass Correlation Coefficient ◽

Rheumatic Diseases ◽

Femoral Condyle ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Concordance Correlation Coefficient ◽

Image Method ◽

Concordance Correlation ◽

Gray Scale

Background:The gray scale (GS) in high resolution ultrasound is already well validated for use in rheumatological diseases, but the color map or the histogram, can be considered a new proposal, to better define and complement the echotextural damages detection1.Objectives:To calculate the lesions area measures reproducibility index in arthropathies, between 3 blind evaluators and correlate these measures using the GS and the histogram.Methods:Observational and retrospective study approved by the ethics committee of the Pontifical Catholic University of Campinas, with the opinion number: 1.526.307. A total of 29 patients have been assessed (31% males and 69% females) on period 2014 to 2019 in Rheumatology service. A MyLab 50 -Esaote equipment was used with frequency transducer that ranged between 6.0 and 18.0 MHz, 10 different area measures were performed from each recorded images previously, by the GS and the histogram. Statistical analysis: Spearman’s correlation coefficients, Lin’s concordance coefficient (CCC) and the intraclass correlation coefficient (ICC) and their respective 95% confidence intervals, with the SPSS software package for Windows v. 17.0 (SPSS Inc., Chicago, IL, USA).Results:Average age 43.5 ± 21.5 years of age; with disease duration that varied between ≤ 1 month (48.3%) and ≥36 months (24.1%); with the following diseases: juvenile idiopathic arthritis (17.24%); osteoarthritis (13.79%); psoriatic arthritis (13.79%); undifferentiated spondyloarthritis (3.44%); gout (20.68%); rheumatoid arthritis (27.58%) and reactive arthritis (3.44%). A total of 840 measures of exudative (27.58%), proliferative (27.58%) and snowstorm appearance (6.89%) synovitis were performed; femoral-condyle cartilage (3.44%); synovial cyst (3.44%); paratendinitis (6.89%); calcification (3.44%); nail enthesitis (3.44%); tenosynovitis (6.89%) and tophi (10.34%) (Figure 1). The concordance correlation coefficient showed values closer to 1; p <0.001, the intraclass correlation coefficients with excellent reproducibility (ICC ≥ 0.75); p <0.001, always in relation to the three evaluators (Table 1) and the Spearman correlation between the GS and the histogram ranged from rs = 0.665 to rs = 1,000; p <0.001.Conclusion:The histogram can be considered an image method to better identify echotextural damages.References:[1]Mendonça J, Provenza J, Guissa V, et al AB1059 2D Histogram Ultrasound and 3D Ultrasound Correlation in Rheumatic Diseases Annals of the Rheumatic Diseases 2015; 74:1253-1254.Table 1.Concordance Correlation Coefficient (CCC) and Intraclass Correlation Coefficient (ICC):EvaluatorsGS - CCC(IC 95%)p-valorHistogram (IC 95%)p-valor1 e 20,998(0,994-0,999)<0,0010,999(0,995-1,000)<0,0011 e 30,998(0,995-0,999)<0,0010,999(0,995-1,000)<0,0012 e 30,992(0,980-0,997)<0,010,996(0,979-0,999)<0,01Standard by US 2DICCp-valorGS0,997(0,992-0,999)<0,001Histogram0,998(0,992-0,999)<0,001Legends: Gray Scale (GS).Figure 1.Patient with gout: A and B: Tophi area measures (star) in right metatarsos and efusion (arrow) by GS (45 mm2) and histogram (39 mm2), respectively.Disclosure of Interests:José Alexandre Mendonça Speakers bureau: Novartis, Janssen, Bristol, UCB, Isabella Siste de Almeida Aoki: None declared, Caique Chagas Cavuto: None declared, Vânia Aparecida Leandro-Merhi: None declared, José Luis Braga de Aquino: None declared

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A Quantitative Comparison of Multispectral Refraction Topography and Autorefractometer in Young Adults

Frontiers in Medicine ◽

10.3389/fmed.2021.715640 ◽

2021 ◽

Vol 8 ◽

Author(s):

Yunru Liao ◽

Zhenlan Yang ◽

Zijing Li ◽

Rui Zeng ◽

Jing Wang ◽

...

Keyword(s):

Correlation Coefficient ◽

Pearson Correlation ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Cross Sectional Study ◽

Cross Sectional ◽

High Agreement ◽

Intraclass Correlation Coefficients ◽

Repeatability And Reproducibility ◽

The Mean

Purpose: Purpose of this study is to evaluate the measuring consistency of central refraction between multispectral refraction topography (MRT) and autorefractometry.Methods: This was a descriptive cross-sectional study including subjects in Sun Yat-sen Memorial Hospital from September 1, 2020, to December 31, 2020, ages 20 to 35 years with a best corrected visual acuity of 20/20 or better. All patients underwent cycloplegia, and the refractive status was estimated with autorefractometer, experienced optometrist and MRT. We analyzed the central refraction of the autorefractometer and MRT. The repeatability and reproducibility of values measured using both devices were evaluated using intraclass correlation coefficients (ICCs).Results: A total of 145 subjects ages 20 to 35 (290 eyes) were enrolled. The mean central refraction of the autorefractometer was −4.69 ± 2.64 diopters (D) (range −9.50 to +4.75 D), while the mean central refraction of MRT was −4.49 ± 2.61 diopters (D) (range −8.79 to +5.02 D). Pearson correlation analysis revealed a high correlation between the two devices. The intraclass correlation coefficient (ICC) also showed high agreement. The intrarater and interrater ICC values of central refraction were more than 0.90 in both devices and conditions. At the same time, the mean central refraction of experienced optometrist was −4.74 ± 2.66 diopters (D) (range −9.50 to +4.75D). The intra-class correlation coefficient of central refraction measured by MRT and subjective refraction was 0.939.Conclusions: Results revealed that autorefractometry, experienced optometrist and MRT show high agreement in measuring central refraction. MRT could provide a potential objective method to assess peripheral refraction.

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Combining F-Scan and GAITRite® for use in Clinical Gait Analysis: A Validation Study.

10.21203/rs.3.rs-93976/v1 ◽

2020 ◽

Author(s):

Stephanie Speight ◽

Selina Reidy ◽

John Stephenson ◽

Sarah Reel

Keyword(s):

Gait Analysis ◽

Correlation Coefficient ◽

Intraclass Correlation Coefficient ◽

Intraclass Correlation ◽

Cost Effective ◽

Quality Data ◽

Concordance Correlation Coefficient ◽

Concordance Correlation ◽

Mean Values ◽

Level Of Agreement

Abstract BackgroundClinical gait analysis is widely used to aid the assessment and diagnosis of symptomatic pathologies. Equipment based analysis provides clinicians with a more comprehensive assessment using pressure systems such as F-scan, or analysis of the spatial-temporal parameters of gait using GAITRite. There are systems however such as Strideway™ that can measure these parameters simultaneously, but can be expensive. This study aimed to determine whether standalone systems can be used collectively while still providing quality data, as a cost-effective alternative.MethodsTwenty-six participants walked on a standard floor and a GAITRite walkway, three times wearing the F-Scan system. Mid gait protocols were utilised by analysing the contact pressure of the 2 nd metatarsophalangeal joint of the third, fifth and seventh step from each walk. The Bland-Altman method was used to determine a level of agreement between the two surfaces, using mean values from all walks of all participants who successfully completed all required walks. The intraclass correlation coefficient and Lin’s concordance correlation coefficient were calculated as indices of reliability.ResultsThe intraclass correlation coefficient was calculated to be 0.991 and Lin’s concordance correlation coefficient for the data was calculated to be 0.956, indicating very good reproducibility.ConclusionsThe level of agreement in plantar pressures observed on the two surfaces was very high, suggesting that it is feasible to use F-Scan and GAITRite® together in a clinical setting, as an alternative to other less cost-effective standalone systems.

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Measurement of dyspnea in patients treated with mechanical ventilation

American Journal of Critical Care ◽

10.4037/ajcc1999.8.4.254 ◽

1999 ◽

Vol 8 (4) ◽

pp. 254-261 ◽

Cited By ~ 41

Author(s):

J Powers ◽

SJ Bennett

Keyword(s):

Mechanical Ventilation ◽

Correlation Coefficient ◽

Rating Scales ◽

Rank Order ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Criterion Validity ◽

Spearman Rank Order Correlation ◽

Spearman Rank ◽

Test Retest Reliability

BACKGROUND: Dyspnea, or difficult breathing, is common in patients receiving mechanical ventilation; however, dyspnea is not routinely or systematically measured. OBJECTIVE: The primary purpose of this methodological study was to evaluate the test-retest reliability of 5 dyspnea rating scales and the criterion validity of 4 dyspnea rating scales in patients receiving mechanical ventilation. The secondary purpose was to examine the correlations between each of these 5 rating scales and physiological measures of respiratory function. METHODS: The convenience sample consisted of 28 patients on mechanical ventilation during their hospitalization in the intensive care units of a large, inner-city hospital. Patients rated their dyspnea twice at 30-minute intervals on the visual analogue scale, the vertical analogue dyspnea scale, the modified Borg scale, the numerical scale, and the faces scale. Test-retest reliability was computed by using the intraclass correlation coefficient. Criterion validity was evaluated by using the Spearman rank-order correlation coefficient. RESULTS: The 5 rating scales had acceptable test-retest reliabilities, with intraclass correlation coefficients ranging from 0.81 to 0.97. Criterion validity of the 4 scales also was acceptable, with Spearman rank-order correlation coefficients from 0.76 to 0.96. The rating scales were not correlated with most of the physiological variables. At least half of the patients reported moderate to severe dyspnea. CONCLUSION: The scales showed acceptable reliability and validity, and they will be useful in quantifying dyspnea experienced by patients receiving mechanical ventilation. Further work is needed to evaluate the extent and the severity of dyspnea in such patients in order to evaluate the effectiveness of interventions.

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Assessing the Motor Status Score: A Scale for the Evaluation of Upper Limb Motor Outcomes in Patients after Stroke

Neurorehabilitation and Neural Repair ◽

10.1177/154596830201600306 ◽

2002 ◽

Vol 16 (3) ◽

pp. 283-289 ◽

Cited By ~ 56

Author(s):

Mark Ferraro ◽

Jennifer Hogan Demaio ◽

Jennifer Krol ◽

Chris Trudell ◽

Keren Rannekleiv ◽

...

Keyword(s):

Correlation Coefficient ◽

Upper Limb ◽

Pearson Correlation ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Pearson Correlation Coefficient ◽

Maximum Score ◽

Intraclass Correlation Coefficients ◽

Upper Extremity Impairment ◽

Motor Outcomes

The Motor Status Scale (MSS) measures shoulder, elbow (maximum score = 40), wrist, hand, and finger movements (maximum score = 42), and expands the measurement of upper extremity impairment and disability provided by the Fugl-Meyer (FM) score. This work examines the interrater reliability and criterion validity of the MSS performed in patients admitted to a rehabilitation hospital 21 ± 4 days after stroke. Using the MSS and the FM, 7 occupational therapists masked to each other’s judgments, evaluated 12 consecutive patients with stroke. Two therapists evaluated 6 additional patients on consecutive days. Intraclass correlation coefficients were significant for each group of raters for the shoulder/elbow and for the wrist/hand (P < 0.0001); test-retest measures were also significant for the shoulder/elbow (Pearson correlation coefficient r = 0.99, P < 0.004) and for the wrist/hand (Pearson correlation coefficient r = 0.99, P < 0.003). The internal item consistency for the overall MSS was significant (Cronbach alpha = 0.98, P < 0.0001). Finally the correlation between the MSS and the FM (R 2 = 0.964) was significant (P < 0.0001). The MSS affords a reliable and valid assessment of upper limb impairment and disability following stroke.

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Feasibility study of using a Microsoft Kinect for virtual coaching of wheelchair transfer techniques

Biomedical Engineering / Biomedizinische Technik ◽

10.1515/bmt-2015-0206 ◽

2017 ◽

Vol 62 (3) ◽

Cited By ~ 3

Author(s):

Seonhong Hwang ◽

Chung-Ying Tsai ◽

Alicia M. Koontz

Keyword(s):

Motion Tracking ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Transfer Task ◽

Angle Measurement ◽

Microsoft Kinect ◽

Joint Angles ◽

Wheelchair Users ◽

Small Standard Error ◽

Mean Square Errors

AbstractThe purpose of this study was to test the concurrent validity and test-retest reliability of the Kinect skeleton tracking algorithm for measurement of trunk, shoulder, and elbow joint angle measurement during a wheelchair transfer task. Eight wheelchair users were recruited for this study. Joint positions were recorded simultaneously by the Kinect and Vicon motion capture systems while subjects transferred from their wheelchairs to a level bench. Shoulder, elbow, and trunk angles recorded with the Kinect system followed a similar trajectory as the angles recorded with the Vicon system with correlation coefficients that are larger than 0.71 on both sides (leading arm and trailing arm). The root mean square errors (RMSEs) ranged from 5.18 to 22.46 for the shoulder, elbow, and trunk angles. The 95% limits of agreement (LOA) for the discrepancy between the two systems exceeded the clinical significant level of 5°. For the trunk, shoulder, and elbow angles, the Kinect had very good relative reliability for the measurement of sagittal, frontal and horizontal trunk angles, as indicated by the high intraclass correlation coefficient (ICC) values (>0.90). Small standard error of the measure (SEM) values, indicating good absolute reliability, were observed for all joints except for the leading arm’s shoulder joint. Relatively large minimal detectable changes (MDCs) were observed in all joint angles. The Kinect motion tracking has promising performance levels for some upper limb joints. However, more accurate measurement of the joint angles may be required. Therefore, understanding the limitations in precision and accuracy of Kinect is imperative before utilization of Kinect.

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Association of the Anatomical Sacral Slope With Lumbar Lordosis and Pelvic Incidence in Female Patients With Developmental Hip Dysplasia: A Retrospective Cross-sectional Study

10.21203/rs.3.rs-33748/v1 ◽

2020 ◽

Author(s):

Norio Imai ◽

Hayato Suzuki ◽

Atsushi Sakagami ◽

Yuki Hirano ◽

Naoto Endo

Keyword(s):

Correlation Coefficient ◽

Healthy Subjects ◽

Lumbar Lordosis ◽

Pelvic Incidence ◽

Strong Association ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Developmental Dysplasia ◽

Sacral Slope ◽

Dysplasia Of The Hip

Abstract Background:The anatomical sacral slope, considered an anatomical pelvic parameter independent of femoral head centers for measurement, was previously described to strongly correlate withpelvic incidenceon two-dimensional examination of normal healthy subjects. However, the associationbetween anatomical sacral slope and pelvic incidence was unclear in patients withdevelopmental dysplasia of the hip. Thecurrent study aimed to examine the association between anatomical sacral slope and other spinopelvic parameters on plain radiographs in female patients with developmental dysplasia of the hip. Methods:Eighty-four women with developmental dysplasia of the hip were examined. Lumbar lordosis, thoracic kyphosis, pelvic incidence, sacral slope, and anatomical sacral slope, which was deemedthe angle formed by the straight line of the S1 superior endplate and a line at a right angle to the anterior pelvic plane, were determined by plain radiographs. The correlations were examined by Pearson correlation coefficients, and intra- and interrater intraclass correlation coefficients were evaluated forreliability.Results:A strong association was observed between pelvic incidence and anatomical sacral slope (r=0.725, p<0.001). In addition, the association between anatomical sacral slope and lumbar lordosis wassimilar to that between pelvic incidence and lumbar lordosis (r=0.661, p<0.001 and r=0.554, p<0.001, respectively). The intraraterintraclass correlation coefficient values were 0.869 for anatomical sacral slope and 0.824 for pelvic incidence. Furthermore, the interraterintraclass correlation coefficient values were 0.83 for anatomical sacral slope and 0.685 for pelvic incidence. Conclusions:We found that the strong association between anatomical sacral slope and pelvic incidence wasequal to that in normal,healthy subjects. The associationbetweenanatomical sacral slope and lumbar lordosis was equal to that between pelvic incidence and lumbar lordosis. Additionally, the intraclass correlation coefficient value foranatomical sacral slope was slightlyhigher than that forpelvic incidence. We thusconclude that anatomical sacral slope can be considered a helpful anatomical pelvic parameter that isasubstitute for pelvic incidence not only in normal subjectsbut also in patients with developmental dysplasia of the hip.

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Reliability Measurement of Corneal Wavefront Aberrations using Corneal Videokeratograph Atlas 9000

IIUM Medical Journal Malaysia ◽

10.31436/imjm.v18i2.631 ◽

2020 ◽

Vol 18 (2) ◽

Author(s):

Noorshazana Mat Rejab @ Md Rejab ◽

Mohd Radzi Hilmi ◽

Khairidzan Mohd Kamal ◽

Md Muziman Syah Md Mustafa

Keyword(s):

Correlation Coefficient ◽

Intraclass Correlation Coefficient ◽

Spherical Aberration ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Time Interval ◽

Wavefront Aberration ◽

Wavefront Aberrations ◽

The Mean ◽

Reliability Measurement

Introduction: Accurate corneal wavefront aberration measurements are essential in determining patient’s suitability, vision outcomes and patient satisfaction in laser refractive surgeries. This study aimed to evaluate the reliability measurement of higher-order aberration (HOA) using corneal videokeratograph Atlas 9000. Materials and method: 38 eyes of 19 participants were recruited in this study. Comprehensive eye examination was done to ensure all participants eligibility, and any conditions in which obstruct the central cornea were excluded. Corneal wavefront aberrations were measured based on Zernike polynomials. In assessing repeatability, three repetitive measurements in five minutes in a single session were taken by 2 experience examiners. For reproducibility measurement, similar approach was done with the time-interval between measurements was set at one week. Bland-Altman, limits of agreement (LoA) and intraclass correlation coefficients (ICCs) were used to evaluate the reliability measurement. Results: Bland-Altman and LoA findings revealed no significant differences for both repeatability and reproducibility measurement. For repeatability testing, the mean differences for vertical trefoil, oblique trefoil and spherical aberration were -0.096 ± 0.493, 0.001 ± 0.048, 0.008 ± 0.035, 0.004 ± 0.029, 0.010 ± 0.053 with LoA of 1.930, 0.188, 0.138, 0.114, and 0.208 respectively. Intraclass correlation coefficient (ICC) excellent reliability of 0.841 for all parameters. Likewise, reproducibility testing showed similar findings with the mean difference were -0.018 ± 0.091, 0.016 ± 0.061, -0.0004 ± 0.036, -0.002 ± 0.042, 0.003 ± 0.026, with LoA of 0.356, 0.24, 0.141,0.164, and 0.102 respectively. Intraclass correlation coefficient (ICC) shows excellent reliability of more than 0.9 for all parameters. LoA of less than 1.0 were observed in all measurements (except for repeatability of vertical trefoil) indicates high consistency of the measurements. Conclusions: Corneal videokeratograph Atlas 9000 provides excellent HOA measurement reliability.

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