Repeatability,interocular correlation and agreement of optic nerve head vessel density in healthy eyes:a sweptsource optical coherence tomographic angiography study

AIM:To assess the repeatability,interocular correlation,and agreement of quantitative swept-source optical coherence tomography angiography(OCTA)optic nerve head(ONH)parameters in healthy subjects.METHODS:Thir ty-three healthy subjects were enrolled.The ONH of both eyes were imaged four times by a swept-source-OCTA using a 3 mm×3 mm scanning protocol.Images of the radial peripapillary capillary were analyzed by a customized Matlab program,and the vessel density,fractal dimension,and vessel diameter index were measured.The repeatability of the four scans was determined by the intraclass correlation coefficient(ICC).The most well-centered optic disc from the four repeated scans was then selected for the interocular correlation and agreement analysis using the Pearson correlation coefficient,ICC and Bland-Altman plots.RESULTS:All swept-source-OCTA ONH parameters exhibited certain repeatability,with ICC>0.760 and coefficient of variation(CoV)≤7.301%.The obvious interocular correlation was observed for papillary vessel density(ICC=0.857),vessel diameter index(ICC=0.857)and fractal dimension(ICC=0.906),while circumpapillary vessel density exhibited moderate interocular correlation(ICC=0.687).Bland-Altman plots revealed an agreement range of-5.26%to 6.21%for circumpapillary vessel density.CONCLUSION:OCTA ONH parameters demonstrate good repeatability in healthy subjects.The interocular correlations of papillary vessel density,fractal dimension and vessel diameter index are high,but the correlation for circumpapillary vessel density is moderate.

Migration routes of the endangered Oriental Stork(Ciconia boyciana)from Xingkai Lake,China,and their repeatability as revealed by GPS tracking

The Oriental Stork(Ciconia boyciana)is listed as'Endangered'on the International Union for the Conservation of Nature(IUCN)Red List of Threatened Species and is classified as a first category nationally protected bird species in China.Understanding this species'seasonal movements and migration will facilitate effective conservation to promote its population.We tagged 27 Oriental Stork nestlings at Xingkai Lake on the Sanjiang Plain in Heilongjiang Province,China,used GPS tracking to follow them over the periods of 2014-2017 and 2019-2022,and confirmed their detailed migratory routes using the spatial analysis function of ArcGIS 10.7.We discovered four migration routes during autumn migration:one common long-distance migration route in which the storks migrated along the coastline of Bohai Bay to the middle and lower reaches of the Yangtze River for wintering,one short-distance migration route in which the storks wintered in Bohai Bay and two other migration routes in which the storks crossed the Bohai Strait around the Yellow River and wintered in South Korea.There were no significant differences in the number of migration days,residence days,migration distances,number of stopovers and average number of days spent at stopover sites between the autumn and spring migrations(P>0.05).However,the storks migrated significantly faster in spring than in autumn(P=0.03).The same individuals did not exhibit a high degree of repetition in their migration timing and route selection in either autumn or spring migration.Even storks from the same nest exhibited considerable between-individual variation in their migration routes.Some important stopover sites were identified,especially in the Bohai Rim Region and on the Songnen Plain,and we further explored the current conservation status at these two important sites.Overall,our results contribute to the understanding of the annual migration,dispersal and protection status of the endangered Oriental Stork and provide a scientific basis for conservation decisions and the development of action plans for this species.

Repeatability and Reproducibility of Quantitative Assessment of the Retinal Microvasculature Using Optical Coherence Tomography Angiography Based on Optical Microangiography

Objective The aim of this study was to determine the repeatability and reproducibility of optical coherence tomography angiography（OCTA） based on optical microangiography（OMAG） measurements of macular vessels in normal eyes. Methods In this prospective cohort study, 40 eyes of 40 healthy volunteers underwent repeated OCTA（Cirrus HD-OCT 5000 angiography system, Carl Zeiss Meditec, Inc.） scans on two separate visit days. On each visit day, the eyes were scanned three times. The following parameters were used to quantitatively describe the OCTA images of the superficial vascular network： vessel area density（VAD）, vessel skeleton density（VSD）, vessel diameter index（VDI）, vessel perimeter index（VPI）, vessel complexity index（VCI）, flux, and foveal avascular zone（FAZ）. Coefficient of variation（CV） and intraclass correlation coefficient（ICC） were calculated for evaluating intravisit and intervisit repeatability, as well as interobserver reproducibility. Results The measurements showed high repeatability [CVs ≤ 4.2%（intravisit） and ≤ 4.6%（intervisit）] and interobserver reproducibility（ICCs ≥ 0.923） for all parameters. Conclusion This study demonstrated good repeatability and reproducibility of OCTA based on OMAG for the measurement of superficial vessel parameters in normal eyes.

Repeatability and agreement of CCT measurement in myopia using entacam and ultrasound pachymetry

AIM: To evaluate the repeatability of central corneal thickness (CCT) measurement by entacam, and agreement of CCT measured by Pentacam and ultrasound pachymetry (USP) in Chinese myopia. Thereby investigate the possibility of Pentacam as a substitute for USP in CCT measurement before refractive surgery. The effects of corneal curvature measured by Pentacam on CCT were also evaluated. METHODS: One hundred and forty-eight right eyes of 148 individual with myopia were included in this study. Three successive Pentacam CCT measurements followed by 10 successive ultrasound pachymetry were carried out in the 148 eyes. Mean of CCT taken by each device was calculated for comparison. According to the CCT measured by USP, all the 148 eyes were divided into 3 groups: <520 mu m, 520-560 mu m, >560 mu m. For all eyes and each group the CCT obtained by Pentacam and USP were compared. Anterior corneal curvature of the 148 eyes was also adopted for correlation analysis with CCT obtained by ultrasound pachymetry. In addition, CCT measurement using 60 random selected Scheimpflug images was performed by 3 skilled investigators at different time, and this was repeated for 3 times by a forth investigator to assess repeatability of Pentacam CCT measurement using Scheimpflug images. RESULTS: Intraclass correlation coefficient (ICC) analysis revealed high intraobserver repeatability (ICC=0.994, F=158.60, P<0.001) for CCT measurement by Pentacam. The interobserver (ICC=0.998, F =494.73, P <0.001) and intraobserver (ICC=0.997, F=383.98, P<0.001) repeatability for Pentacam CCT measurements using Scheimpflug images were also excellent. There was high positive correlation between the CCT values measured by Pentacam and ultrasound pachymetry (r=0.963, P<0.001). Bland-altman plots showed that the Pentacam underestimate the CCT by 8.02 mu m compared with ultrasouond pachymetry.The differences between Pentacam and USP increased as the CCT readings by USP increased (Pentacam vs USP: slope=-0.04, P< 0.05). The 95% upper and lower limits of agreement between CCT values obtained from the two devices were +9. 33 mu m and -25.37 mu m. No significant association could be found between CCT and anterior corneal curvature. CONCLUSION: Inter- and intraobserver variability for CCT measurements by Pentacam was considerably below clinically significant levels. CCT of myopia obtained by Scheimpflug camera, Pentacam, were highly correlated to that by ultrasound pachymetry. However, the values obtained are not directly interchangeable between Pentacam and ultrasound pachymetry as the 95% limits of agreement are relatively wide. Pentacam can be a useful instrument for measuring CCT in candidates to refractive surgery in clinic.

Repeatability and agreement of two anterior segment OCT in myopic patients before implantable collamer lenses implantation

AIM: To evaluate the intra-operator repeatability of time domain and swept-source Fourier domain anterior segment optical coherence tomography(AS-OCT), namely, Visante ASOCT and Casia SS-1000 OCT, in measuring the preoperative parameters of implantable collamer lens(ICL) in myopic eyes, as well as the agreement between the two devices.METHODS: A total of 97 eyes from 49 myopes were investigated in this prospective case series study. The anterior chamber depth(ACD), angle-to-angle distance(ATA), pupil diameter(PD) and crystalline lens rise(CLR) in all subjects were measured for three times during one session by the same operator. The repeatability was evaluated using the within-subject standard deviation(Sw), repeatability limits and intraclass correlation coefficients(ICC). The agreement between the two systems was evaluated using the Bland-Altman plots and 95% limits of agreement(Lo A).RESULTS: The repeatability limits of Visante AS-OCT in measuring ACD, ATA, PD and CLR were 0.099, 0.141, 0.304, and 0.079 mm, respectively. The repeatability limits of Casia SS-1000 OCT in measuring ACD, ATA, PD, and CLR were 0.105, 0.127, 0.357, and 0.082 mm, respectively. Excellent repeatability could be attained in both devices, with the ICC>0.8 for all the measured variables. The interdevice agreement was excellent(P>0.05) for ACD and ATA, but poor(P<0.05) for PD and CLR.CONCLUSION: Good repeatability can be attained by time domain and swept-source Fourier-domain OCT for all the measured variables. Moreover, interdevice agreement analysis suggests that interchangeable measurements between two devices can be achieved for ACD and ATA, but not for PD and CLR;but the differences in measurements were not clinically significant.

Accuracy and Repeatability of Computer Aided Cervical Vertebra Landmarking in Cephalogram

The accuracy and repeatability of computer aided cervical vertebra landmarking (CACVL) were investigated in cephalogram.120 adolescents (60 boys,60 girls) aged from 9.1 to 17.2 years old were randomly selected.Twenty-seven landmarks from the second to fifth cervical vertebrae on the lat-eral cephalogram were identified.In this study,the system of CACVL was developed and used to iden-tify and calculate the landmarks by fast marching method and parabolic curve fitting.The accuracy and repeatability in CACVL group were compared with those in two manual landmarking groups [orthodon-tic experts (OE) group and orthodontic novices (ON) group].The results showed that,as for the accu-racy,there was no significant difference between CACVL group and OE group no matter in x-axis or y-axis (P>0.05),but there was significant difference between CACVL group and ON group,as well as OE group and ON group in both axes (P<0.05).As for the repeatability,CACVL group was more reli-able than OE group and ON group in both axes.It is concluded that CACVL has the same or higher ac-curacy,better repeatability and less workload than manual landmarking methods.It’s reliable for cervi-cal parameters identification on the lateral cephalogram and cervical vertebral maturation prediction in orthodontic practice and research.

Intraexaminer repeatability and agreement in stereoacuity measurements made in young adults

AIM: To determine the repeatability and agreement of stereoacuity measurements made using some of the most widely used clinical tests: Frisby, TNO, Randot and Titmus.METHODS: Stereoacuity was measured in two different sessions separated by a time interval of at least 24 h but no longer than 1wk in 74 subjects of mean age 20.6y using the four methods. The study participants were divided into two groups: subjects with normal binocular vision and subjects with abnormal binocular vision.RESULTS: Best repeatability was shown by the Frisby and Titmus [coefficient of repeatability(COR): ±13 and±12s arc respectively] in the subjects with normal binocular vision though a clear ceiling effect was noted.In the subjects with abnormal binocular vision, best repeatability was shown by the Frisby(COR: ±69s arc)and Randot(COR: ±72s arc). In both groups, the TNO test showed poorest agreement with the other tests.CONCLUSION:Therepeatabilityofstereoacuitymeasures was low in subjects with poor binocular vision yet fairly good in subjects with normal binocular vision with the exception of the TNO test. The reduced agreement detected between the tests indicates they cannot be used interchangeably.

Repeatability of in-vitro optical quality measurements of intraocular lenses with a deflectometry technique effect of the toricity

AIM： To evaluate the repeatability of an optical device for measuring the Zernike coefficients of toric intraocular lenses（IOLs） and assess whether its toricity has any impact in its repeatability. METHODS： An experienced technician used the NIMO TR1504 to measure the Zernike coefficients 30 times for an aperture of 4.50 mm for all lenses included. The IOLs included were divided into two group： toric and nontoric ones. The cylindrical powers of the toric lenses included in the present study were 1.00, 1.50, 2.25, 3.00 and 3.75 D. Finally, the repeatability of the NIMO TR1504 was described in terms of within subject standard deviation（Sw） and repeatability limit. RESULTS： The Sw was smaller than 0.011 μm for both lens groups and all Zernike coefficients, and the difference between both groups was smaller than 0.004 μm for all Zernike coefficients. Regarding the repeatability limit, this value was smaller than 0.025 μm for the toric lens group, and smaller than 0.031 μm for the non-toric lens one for all Zernike coefficients. Furthermore, the maximum difference between both lens groups was 0.010 μm. CONCLUSION： The repeatability of the NIMO TR1504 to measure the optical quality is high and independent of the lens toricity. These results reflect that this system is robust and could be used to measure the in-vitro optical quality of either toric or non-toric IOLs.

Analysis of the Gas Puffing Performance for Improving the Repeatability of Ohmic Discharges in the SUNIST Spherical Tokamak

The gas puffing performance plays a key role in repeatable discharges in the Sino- UNited Spherical Tokamak （SUNIST） experiments. In this paper, temporal evolution of the gas pressure in the vacuum vessel and the dependence of the repeatability of plasma discharges on different timing arrangements between the gas puffing pulse and the Ohmic field have been experimentally investigated. The results show that, after a fast rising phase, the gas pressure becomes quasi-stationary. In the regime of the discharges being started up when the gas pressure has already reached the quasi-stationary state for about 37 ms, an improved repeatability of the plasma discharges is achieved.

Repeatability of Ophtha Top topography and comparison with IOL-Master and Lenstar LS900 in cataract patients

AIM：To determine the repeatability of Ophtha Top topography and assess the consistency with intraocular lens（IOL）-Master and Lenstar LS900（Lenstar）in measuring corneal parameters among cataract patients.METHODS：Totally 125 eyes were enrolled.Corneas were successively measured with Ophtha Top,IOL-Master and Lenstar at least three times.The flattest meridian power（Kf）,the steepest meridian power（Ks）,mean power（Km）,J0 and J45 were recorded.Intra-class correlation coefficients（ICCs）,the coefficient of variance（COV）,within subject standard deviation（Sw）,and test-retest repeatability（2.77Sw）were adopted to determine the repeatability.The 95%limit of agreement（95%LOA）and Bland-Altman plots were used to assess comparability.RESULTS：Repeatability of Ophtha Top topography for measuring corneal parameters showed the ICCs were all above 0.93,2.77Sw was lower than 0.31,and the COV of the Kf and Ks was lower than 0.25.The keratometric readings with Ophtha Top topography were flatter than with the IOLMaster and Lenstar devices,while the Pearson correlation coefficients were over 0.97.The J0 and J45 with Ophtha Top topography were smaller compared with Lenstar and IOL-Master,while was comparable between Lenstar and IOL-Master.CONCLUSION：Ophtha Top topography shows excellent repeatability for measuring corneal parameters.However,differences between the Ophtha TOP topography and Lenstar,IOL-Master both in cornea curvature and the astigmatism should be noted clinically.

Discussion on Repeatability and Reproducibility of Measuring Method in ISO 5725

This paper discusses the repeatability and reproducibility of the international standard of ISO 5725：1994 Accuracy （trueness and precision） of Measurement Methods and Results, two concepts of ＂inter-laboratory variance＂ and ＂reproducible variance＂ in the standard are questioned, the corresponding improvement idea is introduced, which aims to make this standard more rigorous, scientific and logical.

Evaluation of patient visual comfort and repeatability of refractive values in non-presbyopic healthy eyes

AIMTo evaluate the intra-operator repeatability in healthy subjects using the WAM-5500 auto-kerato/refractometer and the iTrace aberrometer, to compare the refractive values and the subjective refraction obtained with both devices and to determine which of these three spherocylindrical corrections allows the subject to achieve the best visual comfort.METHODSForty-two non-presbyopic healthy eyes of 42 subjects were enrolled in this prospective study. Refractive values were compared, evaluating the repeatability, the relationship between the methods and the best visual comfort obtained.RESULTSSphere, cylinder and axis results showed good intraclass correlation coefficients (ICC); the highest ICC was obtained using the spherical refraction with the autorefractometer and the aberrometer, achieving levels of 0.999 and 0.998, respectively. The power vector (PV) was calculated for each refraction method, and the results indicated that there were no statistically significant differences between them (P&#x0003e;0.05). Direct comparison of PV measurements using the three methods showed that aberrometer refraction gave the highest values, followed by the subjective values; the autorefractometer gave the lowest values. The subjective method correction was most frequently chosen as the first selection. Equal values were found for the autorefractometer and the aberrometer as the second selection.CONCLUSIONThe iTrace aberrometer and the WAM-5500 auto-kerato/refractometer showed high levels of repeatability in healthy eyes. Refractive corrections with the aberrometer, the autorefractometer and subjective methods presented similar results, but spherocylindrical subjective correction was the most frequently selected option. These technologies can be used as complements in refractive evaluation, but they should not replace subjective refraction.

Two-Fold and Symmetric Repeatability Rates for Comparing Keypoint Detectors

The repeatability rate is an important measure for evaluating and comparing the performance of keypoint detectors.Several repeatability rate measurementswere used in the literature to assess the effectiveness of keypoint detectors.While these repeatability rates are calculated for pairs of images,the general assumption is that the reference image is often known and unchanging compared to other images in the same dataset.So,these rates are asymmetrical as they require calculations in only one direction.In addition,the image domain in which these computations take place substantially affects their values.The presented scatter diagram plots illustrate how these directional repeatability rates vary in relation to the size of the neighboring region in each pair of images.Therefore,both directional repeatability rates for the same image pair must be included when comparing different keypoint detectors.This paper,firstly,examines several commonly utilized repeatability rate measures for keypoint detector evaluations.The researcher then suggests computing a two-fold repeatability rate to assess keypoint detector performance on similar scene images.Next,the symmetric mean repeatability rate metric is computed using the given two-fold repeatability rates.Finally,these measurements are validated using well-known keypoint detectors on different image groups with various geometric and photometric attributes.

Acquisition repeatability of MRI radiomics features in the head and neck:a dual-3D-sequence multi-scan study

Radiomics has increasingly been investigated as a potential biomarker in quantitative imaging to facilitate personalized diagnosis and treatment of head and neck cancer(HNC),a group of malignancies associated with high heterogeneity.However,the feature reliability of radiomics is a major obstacle to its broad validity and generality in application to the highly heterogeneous head and neck(HN)tissues.In particular,feature repeatability of radiomics in magnetic resonance imaging(MRI)acquisition,which is considered a crucial confounding factor of radiomics feature reliability,is still sparsely investigated.This study prospectively investigated the acquisition repeatability of 93 MRI radiomics features in ten HN tissues of 15 healthy volunteers,aiming for potential magnetic resonance-guided radiotherapy(MRgRT)treatment of HNC.Each subject underwent four MRI acquisitions with MRgRT treatment position and immobilization using two pulse sequences of 3D T1-weighed turbo spin-echo and 3D T2-weighed turbo spin-echo on a 1.5T MRI simulator.The repeatability of radiomics feature acquisition was evaluated in terms of the intraclass correlation coefficient(ICC),whereas within-subject acquisition variability was evaluated in terms of the coefficient of variation(CV).The results showed that MRI radiomics features exhibited heterogeneous acquisition variability and uncertainty dependent on feature types,tissues,and pulse sequences.Only a small fraction of features showed excellent acquisition repeatability(ICC>0.9)and low within-subject variability.Multiple MRI scans improved the accuracy and confidence of the identification of reliable features concerning MRI acquisition compared to simple test-retest repeated scans.This study contributes to the literature on the reliability of radiomics features with respect to MRI acquisition and the selection of reliable radiomics features for use in modeling in future HNC MRgRT applications.

Research on the Characteristics and Repeatability of Strong Earthquake Activity in Sichuan-Yunnan

According to the method for predicting strong earthquakes using seismicity patterns,this paper summarizes the seismicity anomalies, generally called anomalous seismicity patterns,as the basis for prediction based on some historical data in the Sichuan-Yunnan seismic zone. Using our results,it can be confirmed that these anomaly patterns,which reflect the features of the late stage of strong earthquake preparation process and stress release in the main shock rupture zone,did exist before many earthquake cases. This paper also introduced the characteristics of seismic repeatability and its validation result,and discussed the mechanism of repeatability,which will have an application value for strong earthquake tendency prediction.

Analysis Of Repeatability For Measurements Of Veiling Glare Index

Various factors that affect the repeatability of an apparatusfor the measurement of veiling glare index of a long focal length opticalsystem are discussed,which include the errors influencing the radianceuniformity of the extended bright field,positions of the detector,measuring aperture,and the black patch.The results can be used in thedesign of any veiling glare measurement apparatus.

Repeatability of Pre-Harvest Sprouting in Wheat

This study aimed to detect genotypic differences in the resistance to sprouting of wheat grains, evaluate the effectiveness of different methods for inducing sprouting and identify, using repeatability estimates, the minimum number of spikes necessary for the adequate evaluation of the percentage of grain sprouting in the spike in order to assist in the selection of superior genotypes in breeding programs. Spikes from four wheat cultivars (Frontana, IPR Catuara, Quartzo and BRS 220) were evaluated using three methods for inducing grain sprouting in the spike (water immersion, rainfall simulation and germination chamber). To determine the most efficient method, repeatability coefficients were estimated through analysis of variance, principal components analysis and structural analysis based on correlation and covariance matrices. The induction of sprouting by immersion in water was the most effective method for indicating genotypic differences and may be used in breeding programs for this purpose. The repeatability method based on the components of covariance was more efficient. A minimum of 11 spikes is required to make a high-reliability estimate of the percentage of sprouted grains in the spike.

MATHEMATICAL MODEL OF REPEATABILITY FOR ROBOTS

The influences of joints' error, motion history, speed and robot posture on repeatability are analyzed and the mathematical expressions of the quantity, direction and distribution of the stochastic positional error are derived . Using this model the magnitude and direction of the stochastic positional error after any motion can be preestimated and compensated .

Selective laser trabeculoplasty:a review of repeatability

The efficacy of selective laser trabeculoplasty(SLT)to treat open-angle glaucoma(OAG)and ocular hypertension(OHT)has been increasingly substantiated lately.Repeated SLT is usually needed to control intraocular pressure(IOP),be it as primary or adjunctive therapy.We review the studies available,in terms of SLT repeatability;and conclude comparable efficacy,with success rate,duration and complications similar to those in initial SLT.

Repeatability and reproducibility of corneal higher-order aberrations measurements after small incision lenticule extraction using the Scheimpfug-Placido topographer

Background:To evaluate the precision of corneal higher-order aberrations measurements after small incision lenticule extraction(SMILE)using the Sirius Scheimpfug-Placido topographer(CSO,Italy).Methods:Seventy-fve eyes from 75 postoperative subjects were included in this prospective study.Three consecutive corneal aberrometric measurements were obtained with the Scheimpfug-Placido topographer by two experienced operators to assess intra-and inter-observer reproducibility.The within-subject standard deviation(Sw),test-retest repeatability(TRT)and the intraclass correlation coefcient(ICC)were calculated.Results:For intraobserver repeatability of anterior and total corneal aberrations,all ICCs were more than 0.922,except for trefoil(0.722 to 0.768).The ICCs of total root mean square(RMS),coma Z(3,±1),and spherical aberration Z(4,0)were over 0.810 while higher-order RMS,trefoil Z(3,±3),and astigmatism II Z(4,±2)were below 0.634 for posterior corneal surface aberrations.All Sw values for all types of aberrations were equal to or below 0.07μm.Regarding interobserver reproducibility,all TRT values were no more than 0.12μm,0.05μm,and 0.11μm for anterior,posterior,and total corneal aberrations,respectively.The ICC values ranged from 0.875 to 0.989,from 0.686 to 0.976 and over 0.834 for anterior,posterior,and total corneal aberrations,respectively.Conclusions:The repeatability of measurements of anterior and total corneal aberrations with the Sirius system in corneas after SMILE surgery was high,except for trefoil.There was some variability in posterior corneal aberrometric measurements.High reproducibility of corneal aberrometric measurements was observed between measurements of both examiners,except for trefoil,with poor to moderate reproducibility.