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This study aimed to evaluate the intraobserver repeatability and interobserver reproducibility of the LUS-1000 Plus, a new fully automatic optical low coherence reflectometry (OLCR)-based biometer, and its agreement with the IOLMaster 700, a swept-source optical coherence tomography (SS-OCT)-based biometer, for biometric measurement.
Methods
This prospective study included 77 right eyes from 77 healthy participants. The axial length (AL), central corneal thickness (CCT), aqueous depth (AQD), anterior chamber depth (ACD), flattest, steepest, mean keratometry (Kf, Ks, Km), astigmatism magnitude (AST), J0, J45 vectors, and corneal diameter (CD) were measured. Repeatability and reproducibility were evaluated using the within-subject standard deviation (Sw), test–retest (TRT) repeatability, coefficient of variation (CoV), and intraclass correlation coefficient (ICC). To compare differences and establish agreement between the devices, paired t test and Bland–Altman plots were utilized. Double-angle plots were employed to analyze corneal astigmatism.
Results
Repeatability and reproducibility analysis revealed low Sw, TRT, and CoV, accompanied by high ICC values for all evaluated parameters. The interdevice agreement was excellent, Bland–Altman plots showed narrow 95% limits of agreement (LoA) (AL − 0.05 to 0.04 mm, CCT − 22.03 to − 7.50 μm, AQD 0.01 to 0.14 mm, ACD 0.00 to 0.13 mm, LT − 0.16 to 0.02 mm, Kf − 0.24 to 0.23 D, Ks − 0.36 to 0.21 D, Km − 0.24 to 0.16 D, AST − 0.41 to 0.27 D, J0 − 0.15 to 0.17 D, J45 − 0.14 to 0.22 D, CD − 0.38 to 0.18 mm).
Conclusion
The LUS-1000 Plus demonstrated high repeatability and reproducibility, and excellent agreement with the IOLMaster 700, confirming its reliability and interchangeable use with the IOLMaster 700 in clinical practice.
Chak Seng Lei and Xinning Yang contributed equally as first authors.
Key Summary Points
Why carry out this study?
Precise ocular biometry is fundamental for clinical diagnosis, treatment, and accurate intraocular lens power calculations.
The LUS-1000 Plus is a new fully automatic optical low coherence reflectometry (OLCR)-based biometer that has not been studied. The IOLMaster 700 is a validated swept source optical coherence tomography (SS-OCT)-based biometer. Evaluating the precision of the new device and its agreement with a validated device is essential.
What was learned from the study?
The LUS-1000 Plus is a reliable device with excellent intraobserver repeatability and interobserver reproducibility.
Measurements from this new OLCR-based biometer showed excellent agreement with the established IOLMaster 700, indicating that these devices can be used interchangeably in clinical practice.
Introduction
Ocular biometry is a critical component in ophthalmology. Biometric parameters are essential for monitoring disease progression and calculating intraocular lens (IOL) power for cataract surgery, where accurate measurements of the eye’s anatomical structures are indispensable for optimal outcomes [1]. Additionally, axial length (AL) measurements are useful for monitoring myopia progression, a growing concern in pediatric and adolescent populations [2]. Central corneal thickness (CCT) has wide clinical applications, including intraocular pressure (IOP) correction [3], glaucoma management [4], assessment for refractive surgery and keratoconus detection [5]. Anterior chamber depth (ACD) is a key indicator for phakic IOLs implantation, as it ensures postoperative vault and safety [6]. Lens thickness (LT) is included in the modern IOL formulas to improve accuracy [7]. Keratometry (K) and corneal diameter (CD) are crucial for IOL power calculation and contact lens fitting [8].
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The LUS-1000 Plus (MEDA Co., Ltd., China) is a newly developed biometer, utilizing optical low coherence reflectometry (OLCR) for biometric measurements. Its primary advantage is the capability for fully automatic measurement, which enhances ease of use and minimizes operator-dependent variability. Current biometric devices often required manual adjustments and can be limited by user experience, highlighting the need for more automated solutions that maintain high accuracy. Implementing automated biometry in primary care or schools can provide an effective means of ocular disease screening and myopia control without the necessity for specialists, which can be particularly beneficial in underserved communities [9, 10].
As a new instrument, clinicians often prioritize the precision of its measurements and how they compare to the gold standard [11]. The IOLMaster 700 (Carl Zeiss Meditec AG, Germany) is a validated swept-source optical coherence tomography (SS-OCT) biometer with excellent precision and high agreement with other ophthalmic instruments [12, 13]. The aim of our present study was to evaluate the intraobserver repeatability and interobserver reproducibility of the LUS-1000 Plus and to explore its interchangeability with the IOLMaster 700.
Methods
Subjects
This prospective study adhered to the tenets of the Declaration of Helsinki and received approved from the Institutional Ethics Committee of the Eye and ENT Hospital of Fudan University, Shanghai, China (No. 2021175). Healthy participants were recruited at the Eye and ENT Hospital of Fudan University. Written consent forms were signed by all participants after the study’s purpose and procedures were fully explained.
All participates underwent a comprehensive ophthalmic examination, including manifest refraction, slit-lamp microscopy, non-contact tonometry, and indirect ophthalmoscopy. Inclusion criteria were (1) aged 18 years or older, (2) best corrected visual acuity (BCVA) of 20/20 or better, (3) a minimum of 2 weeks cessation of soft contact lens wear or 4 weeks cessation of rigid contact lens wear. Exclusion criteria were (1) symptoms of dry eye, (2) corneal ectasia disease or corneal scarring, (3) history of ophthalmic diseases (such as glaucoma or cataract), ocular surgery or trauma, (4) poor fixation during examination.
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Instruments and Parameters
LUS-1000 Plus
The LUS-1000 Plus is a new fully automated OLCR-based biometer, utilizing a light source with a center wavelength of 840 nm to measure AL, CCT, aqueous depth (AQD), and LT. AQD is defined as the distance between the corneal endothelium and the anterior lens surface, with ACD calculated as the sum of AQD and CCT [14]. K values are calculated from 32 projection points on two concentric rings with diameters of 1.65 and 2.30 mm on the anterior corneal surface, using the standardized keratometric index of 1.3375. CD and pupil diameter (PD) are determined by identifying the boundaries of the cornea and pupil in eye photograph. The measurement ranges are 12–34 mm for AL, 300–800 μm for CCT, 1.5–6.0 mm for AQD, 0.5–7.0 mm for LT, radii 4.7–11.2 mm for corneal, and 6.5–16.6 mm for CD. The LUS-1000 Plus automates alignment and measurement after pressing the start button, averaging five consecutive measurements to provide a single data output.
IOLMaster 700
The IOLMaster 700 is an SS-OCT-based biometer, utilizing a tunable laser with a wavelength of 1050 nm to measure AL, CCT, AQD, ACD, and LT. AQD and ACD are defined as the distances between the corneal endothelium or epithelium and the anterior lens surface, respectively [14]. K values are measured using telecentric keratometry with 18 reflective spots on three concentric rings (1.5, 2.5, 3.5 mm optical zones) on the anterior corneal surface; the standardized keratometric index of 1.3375 was used in this study. CD and PD are captured by integrated camera system. The measurement ranges are 14–38 mm for AL, 200–1200 μm for CCT, 0.7–8.0 mm for ACD, 1–10 mm for LT, 5–11 mm for corneal radii, and 8–16 mm for CD.
Measurement Technique
All measurements were taken between 10:00 and 17:00 to minimize the impact of the diurnal variations in corneal curvature and thickness [15]. One skilled operator conducted measurements using the LUS-1000 Plus and the IOLMaster 700; another skilled operator measured the same subjects using only the LUS-1000 Plus. The sequence of measurements was randomized to prevent methodological bias. Before each measurement session, all devices were calibrated according to the instruction manuals. First, in a dimly lit room, non-mydriatic subjects were instructed to place their chin on the chinrest and their forehead against the headrest of the device, then stare at the internal fixation light and blink before each measurement to ensure an intact tear film over the corneal surface. Three consecutive valid results were required for each device. The whole procedure was limited to a 15-min timeframe.
The following biometric parameters were assessed: AL, CCT, AQD, ACD, LT, flattest keratometry (Kf), steepest keratometry (Ks), mean keratometry (Km, Km = (Kf + Ks)/2), astigmatism magnitude (AST, AST = Ks − Kf), J0, J45 vectors, and CD. Based on Fourier transformation, corneal astigmatism was transformed into two power vectors: J0 (Jackson cross-cylinder at 0° axis) and J45 (Jackson cross-cylinder at 45° axis). The calculation formulas were as follows: J0 = − (AST/2) × cos(2α), J45 = − (AST/2) × sin(2α), where α denotes the cylindrical axis [16].
Statistical Analysis
SPSS (version 25, IBM Corporation, New York, USA), MedCalc statistical software (version 22, MedCalc Software Ltd., Ostend, Belgium), and Microsoft Office Excel 365 (Microsoft Corporation, Washington, USA) were used to perform statistical analysis.
The normal distribution was evaluated using the Kolmogorov–Smirnov test (P > 0.05) and data were presented as mean ± standard deviation (SD). To assess the intraobserver repeatability and interobserver reproducibility of the LUS-1000 Plus, the within-subject standard deviation (Sw), test–retest (TRT) repeatability, coefficients of variation (CoV), and intraclass correlation coefficient (ICC) were computed and evaluated [17]. The TRT, defined as 2.77 × Sw, quantifies the variability of repeated measurements taken from the same subject; lower Sw and TRT values represent higher repeatability. The CoV is calculated as the ratio of the Sw to the within-subject mean and expressed as a percentage; a lower CoV also signifies higher repeatability. ICC ranges from 0 to 1; an ICC closer to 1 indicates greater consistency. To analyze interdevice agreement, the mean values of each device from the same observer were compared using paired t test. Bland–Altman plots were constructed with the 95% limits of agreement (LoA) defined as the mean difference ± 1.96 SD [18]. Corneal astigmatism obtained by each device and interdevice differences were described by double-angle plots. These plots were generated with the Astigmatism Double Angle Plot Tool from the American Society of Cataract and Refractive Surgery (ASCRS) website, which displays the magnitude and meridian of the average astigmatism (centroid) and the confidence ellipse.
Results
A total of 77 right eyes from 77 healthy participants (27 male and 50 female) were enrolled. The mean age was 28.30 ± 6.15 years (range 18–46 years). The average equivalent spherical power was − 5.64 ± 1.98 diopters (D) (range − 12.875 to − 0.50 D), the average spherical power was − 5.25 ± 1.89 D (range − 12.25 to − 0.25 D), and the average cylinder power was − 0.79 ± 0.65 D (range − 2.75 to 0.00 D).
Table 1 displays the intraobserver repeatability of the LUS-1000 Plus biometric measurements. The AL demonstrated near-perfect repeatability values (ICC 1.000, Sw 0.02 mm, TRT 0.06 mm, CoV 0.08%). CCT also showed high repeatability (ICC 0.984–0.985, Sw 3.70–3.82 μm, TRT 10.24–10.59 μm, CoV 0.69–0.71%). For AQD, ACD, LT and CD, the Sw and TRT values were low (Sw 0.02–0.06 mm, TRT 0.06–0.15 mm). For Kf, Ks, Km, AST, J0 and J45, the Sw and TRT values were consistently low (Sw 0.07–0.16 D, TRT 0.20–0.45 D). The CoV ranged from 0.08% to 1.53%; the ICCs were generally above 0.944, except for J45 which showed higher variability with ICCs of 0.687–0.729.
Table 1
Intraobserver repeatability of biometric measurements by the LUS-1000 Plus
Parameter
Observer
Mean ± SD
Sw
TRT
CoV (%)
ICC (95% CI)
AL (mm)
1st
25.80 ± 1.08
0.02
0.06
0.08
1.000 (0.999–1.000)
2nd
25.80 ± 1.09
0.02
0.06
0.08
1.000 (0.999–1.000)
CCT (μm)
1st
538.61 ± 30.25
3.70
10.24
0.69
0.985 (0.977–0.991)
2nd
538.68 ± 30.35
3.82
10.59
0.71
0.984 (0.976–0.990)
AQD (mm)
1st
3.15 ± 0.24
0.02
0.07
0.79
0.990 (0.984–0.993)
2nd
3.15 ± 0.24
0.02
0.06
0.64
0.993 (0.989–0.996)
ACD (mm)
1st
3.69 ± 0.24
0.03
0.07
0.69
0.989 (0.983–0.993)
2nd
3.69 ± 0.24
0.02
0.06
0.54
0.993 (0.989–0.996)
LT (mm)
1st
3.66 ± 0.26
0.05
0.14
1.38
0.962 (0.943–0.976)
2nd
3.66 ± 0.25
0.06
0.15
1.53
0.952 (0.928–0.969)
Kf (D)
1st
42.53 ± 1.32
0.09
0.25
0.21
0.995 (0.993–0.997)
2nd
42.52 ± 1.30
0.11
0.31
0.26
0.993 (0.989–0.995)
Ks (D)
1st
43.54 ± 1.40
0.12
0.34
0.28
0.992 (0.988–0.995)
2nd
43.51 ± 1.38
0.15
0.41
0.34
0.988 (0.982–0.993)
Km (D)
1st
43.03 ± 1.32
0.08
0.22
0.19
0.996 (0.994–0.998)
2nd
43.01 ± 1.30
0.10
0.29
0.24
0.994 (0.990–0.996)
AST (D)
1st
1.00 ± 0.68
0.14
0.40
–
0.957 (0.935–0.972)
2nd
0.99 ± 0.68
0.16
0.45
–
0.944 (0.916–0.964)
J0 (D)
1st
− 0.46 ± 0.36
0.07
0.20
–
0.958 (0.937–0.973)
2nd
− 0.45 ± 0.36
0.08
0.23
–
0.948 (0.921–0.967)
J45 (D)
1st
0.08 ± 0.13
0.08
0.21
–
0.729 (0.621–0.817)
2nd
0.09 ± 0.12
0.08
0.21
–
0.687 (0.568–0.786)
CD (mm)
1st
11.95 ± 0.40
0.05
0.13
0.39
0.986 (0.979–0.991)
2nd
11.95 ± 0.40
0.04
0.12
0.38
0.988 (0.981–0.992)
AL axial length, CCT central corneal thickness, AQD anterior aqueous depth, ACD anterior chamber depth, LT lens thickness, Kf flattest keratometry, Ks steepest keratometry, Km mean keratometry, AST astigmatism magnitude, J0 Jackson cross-cylinder at 0°, J45 Jackson cross-cylinder at 45°, CD corneal diameter, SD standard deviation, Sw within-subject standard deviation, TRT test–retest repeatability (2.77 Sw), CoV within-subject coefficient of variation, ICC intraclass correlation coefficient, CI confidence interval
Table 2 displays the interobserver reproducibility of the LUS-1000 Plus biometric measurements. All evaluated parameters yielded high reproducibility, with low Sw, TRT, CoV, and high ICC values. The TRT was 0.04 mm for AL, 6.47 μm for CCT, 0.03 mm for AQD, 0.03 mm for ACD, 0.08 mm for LT, 0.16 D for Kf, 0.20 D for Ks, 0.14 D for Km, 0.23 D for AST, 0.11 D for J0, 0.12 D for J45, and 0.12 mm for CD. The CoV ranged from 0.05% to 0.83%; the ICCs all exceeded 0.985, except the J45 with ICC of 0.883.
Table 2
Interobserver reproducibility of biometric measurements by the LUS-1000 Plus
Parameter
Mean ± SD
Sw
TRT
CoV (%)
ICC (95% CI)
AL (mm)
25.80 ± 1.09
0.01
0.04
0.05
1.000 (1.000–1.000)
CCT (μm)
538.64 ± 30.25
2.33
6.47
0.43
0.994 (0.990–0.996)
AQD (mm)
3.15 ± 0.24
0.01
0.03
0.36
0.998 (0.996–0.999)
ACD (mm)
3.69 ± 0.24
0.01
0.03
0.31
0.998 (0.996–0.999)
LT (mm)
3.66 ± 0.25
0.03
0.08
0.83
0.986 (0.976–0.991)
Kf (D)
42.52 ± 1.31
0.06
0.16
0.14
0.998 (0.997–0.999)
Ks (D)
43.52 ± 1.39
0.07
0.20
0.16
0.997 (0.996–0.998)
Km (D)
43.02 ± 1.31
0.05
0.14
0.12
0.999 (0.998–0.999)
AST (D)
1.00 ± 0.68
0.08
0.23
–
0.985 (0.975–0.991)
J0 (D)
− 0.46 ± 0.36
0.04
0.11
–
0.987 (0.978–0.992)
J45 (D)
0.09 ± 0.12
0.04
0.12
–
0.883 (0.811–0.928)
CD (mm)
11.95 ± 0.40
0.04
0.12
0.35
0.989 (0.982–0.993)
AL axial length, CCT central corneal thickness, AQD anterior aqueous depth, ACD anterior chamber depth, LT lens thickness, Kf flattest keratometry, Ks steepest keratometry, Km mean keratometry, AST astigmatism magnitude, J0 Jackson cross-cylinder at 0°, J45 Jackson cross-cylinder at 45°, CD corneal diameter, SD standard deviation, Sw within-subject standard deviation, TRT test–retest repeatability (2.77 Sw), CoV within-subject coefficient of variation, ICC intraclass correlation coefficient, CI confidence interval
Table 3 presents the means and SD of the differences in the device comparisons and their 95% LoAs, whereas the corresponding Bland–Altman plots are depicted in Fig. 1. Statistically significant differences were observed for all parameters (P < 0.05), except for Kf (P = 0.688) and J0 vector (P = 0.420). However, as evidenced by narrow 95% LoAs from the Bland–Altman analyses (AL − 0.05 to 0.04 mm, CCT − 22.03 to − 7.5 μm, AQD 0.01 to 0.14 mm, ACD 0.00 to 0.13 mm, LT − 0.16 to 0.02 mm, Kf − 0.24 to 0.23 D, Ks − 0.36 to 0.21 D, Km − 0.24 to 0.16 D, AST − 0.41 to 0.27 D, J0 − 0.15 to 0.17 D, J45 − 0.14 to 0.22 D, CD − 0.38 to 0.18 mm), the interdevice agreement was high. Double-angle plots (Fig. 2) demonstrated the overall distribution of datasets and centroids for each device (LUS-1000 Plus: 0.97 D @ 87° ± 0.77 D; IOLMaster 700: 0.97 D @ 85° ± 0.71 D) bore a close resemblance. The pairwise differences in astigmatism between the LUS-1000 Plus and IOLMaster 700 (Fig. 3) were mostly within 0.50 D and the centroid was close to zero (0.08D @ 38° ± 0.24 D).
Table 3
Comparison of biometric measurements between the LUS-1000 Plus and IOLMaster 700
Parameter
Mean difference ± SD
P value
95% LoA
AL (mm)
− 0.01 ± 0.02
0.007
− 0.05 to 0.04
CCT (μm)
− 14.76 ± 3.71
< 0.001
− 22.03 to − 7.50
AQD (mm)
0.08 ± 0.03
< 0.001
0.01 to 0.14
ACD (mm)
0.06 ± 0.03
< 0.001
0.00 to 0.13
LT (mm)
− 0.07 ± 0.05
< 0.001
− 0.16 to 0.02
Kf (D)
− 0.01 ± 0.12
0.688
− 0.24 to 0.23
Ks (D)
− 0.08 ± 0.15
< 0.001
− 0.36 to 0.21
Km (D)
− 0.04 ± 0.10
0.001
− 0.24 to 0.16
AST (D)
− 0.07 ± 0.17
0.001
− 0.41 to 0.27
J0 (D)
0.01 ± 0.08
0.420
− 0.15 to 0.17
J45 (D)
0.04 ± 0.09
< 0.001
− 0.14 to 0.22
CD (mm)
− 0.10 ± 0.14
< 0.001
− 0.38 to 0.18
AL axial length, CCT central corneal thickness, AQD anterior aqueous depth, ACD anterior chamber depth, LT lens thickness, Kf flattest keratometry, Ks steepest keratometry, Km mean keratometry, AST astigmatism magnitude, J0 Jackson cross-cylinder at 0°, J45 Jackson cross-cylinder at 45°, CD corneal diameter, LoA limits of agreement, SD standard deviation
Fig. 1
Bland–Altman plots show agreement of a axial length, b central corneal thickness, c anterior chamber depth, d aqueous depth, e lens thickness, f mean keratometry, g vector J0, h vector J45, i corneal diameter between the LUS-1000 Plus and IOLMaster 700. The solid blue line represents the mean difference (bias). The upper and lower red dashed lines represent the 95% limits of agreement
Conducting a validation study for any new instrument is essential for its clinical application, ensuring that it delivers accurate data [17]. The LUS-1000 Plus is a newly developed biometer, with the main advantage of providing fully automatic measurements for ocular parameters. In this current study, it demonstrated low Sw, TRT, and CoV values across all evaluated parameters, coupled with high ICC values, confirming its high intraobserver repeatability and interobserver reproducibility. Meanwhile, our findings indicated that the interdevice differences between the LUS-1000 Plus and the validated IOLMaster 700 were clinically insignificant, revealing excellent agreement and interchangeability.
Regarding the measurement of AL, a mean difference of − 0.01 ± 0.02 mm was exhibited between LUS-1000 Plus and IOLMaster 700. While this difference was statistically significant, it lacks clinical significance. To illustrate, a 1.0-mm deviation in AL measurement results in a refractive error of about 2.7 D [1]. Therefore, a 0.01-mm AL difference translates to only 0.027 D offset, which is clinically negligible. Song et al. [19] demonstrated excellent AL measurement agreement with a narrow 95% LoA interval (− 0.07 to 0.09 mm) between LS900 (Lenstar, Haag-Streit, Köniz, Switzerland) OLCR-based biometer and IOLMaster 700. Similarly, when comparing the LS900 and IOLMaster 700, Shammas et al. [20] found comparable result with a 95% LoA range of − 0.10 to 0.12 mm. Given these findings, the LUS-1000 Plus and IOLMaster 700 can also be used interchangeably, as evidenced by their 95% LoA ranging from − 0.05 to 0.04 mm.
For CCT measurements, pairwise comparisons indicated that LUS-1000 Plus obtained slightly lower values than those from IOLMaster 700, with a mean difference of − 14.76 ± 3.71 μm. This systematic difference likely stems from both the distinct measurement principles (OLCR versus SS-OCT) and the proprietary algorithms employed by different manufacturers to determine the anterior and posterior corneal boundaries. However, the 95% LoA interval of − 22.03 to − 7.50 μm was smaller than in previous research [21, 22], and this difference was also similar to the diurnal CCT fluctuation [15], so they could be considered in good agreement.
Although the differences of AQD, ACD, and LT were statistically significant, Bland–Altman analyses with narrow 95% LoAs demonstrated high agreement between LUS-1000 Plus and IOLMaster 700 (AQD 0.01 to 0.14 mm, ACD 0.00 to 0.13 mm, LT − 0.16 to 0.02 mm). Arriola-Villalobos et al. [23] established that AQD measurements between IOLMaster 700 and LS900 were in good agreement, since the 95% LoA interval of − 0.09 to 0.06 mm was narrow. However, Gjerdrum et al. [24] conducted a comparative study between ARGOS (Movu, Nagoya, Japan) SS-OCT and LS900, obtaining a wide 95% LoA interval for ACD (− 0.34 to 0.36 mm). With respect to LT measurement, Kunert et al. [25] suggested that the IOLMaster 700 and LS900 were in high agreement with a 95% LoA range of − 0.219 to 0.260 mm. A previous report by Bullimore et al. [12] obtained a 95% LoA ranging from − 0.26 to 0.41 mm between the same two devices. Considering that a 0.1-mm variation in LT or ACD can lead to a shift of 0.10–0.15 D in IOL power [1, 20], the small interdevice discrepancies in AQD, ACD, and LT in our study were clinically insignificant.
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In terms of corneal power measurements, there were very minor differences between the two devices. The mean differences for Kf, Ks, and Km were − 0.01 ± 0.12 D, − 0.08 ± 0.15 D, and − 0.04 ± 0.10 D, respectively. The 95% LoA intervals for Kf, Ks, and Km were − 0.24 to 0.23 D, − 0.36 to 0.21 D, and − 0.24 to 0.16 D, respectively. An agreement study comparing the SS-OCT and OLCR device displayed that the 95% LoA ranges for Kf, Ks, and Km were − 0.37 to 0.43 D, − 0.52 to 0.53 D, and − 0.31 to 0.34 D, respectively [26]. To further comprehensively analyze corneal astigmatism, we employed Fourier power vector analysis and double-angle plots [16, 27]. Likewise, the 95% LoAs were also narrow for AST (− 0.41 to 0.27 D), J0 vector (− 0.15 to 0.17 D), and J45 vector (− 0.14 to 0.22 D). Double-angle plots (Figs. 2, 3) confirmed that the measured astigmatism measurements were similar and the interdevice differences were nearly zero. Cheng et al. [28] conducted an agreement study involving four biometric instruments: ANTERION (Heidelberg, Heidelberg, Germany) SS-OCT, OA-2000 (Tomey, Nagoya, Japan) SS-OCT, LS900, and IOLMaster 700. By focusing on the comparisons between the OLCR and three SS-OCT devices, this study showed that the maximum absolute 95% LoA values were 0.28 D for J0 and 0.23 D for J45. Gao et al. [29] compared the astigmatism measurements between the OA-2000 and Lenstar, reporting excellent agreement with narrow 95% LoAs (J0 − 0.20 to 0.14 D, J45 − 0.14 to 0.20 D). Accordingly, our results indicated the interchangeability of corneal power measurement with excellent agreement in keratometric values and astigmatism between the LUS-1000 Plus and IOLMaster 700.
The corneal diameter (CD) is the horizontal distance between the borders of the corneal limbus [30]. In most ophthalmic instruments, its measurement is processed by imaging software that automatically detects the limbus boundaries on a high-resolution image of the patient’s eye, offering greater precision compared to manual methods [31]. Consequently, detection methods can vary depending on the manufacturer. For instance, the IOLMaster 700 showed good agreement with IOLMaster 500 PCI-based biometer (95% LoA − 0.345 to 0.078 mm) [32], but only moderate agreement with Pentacam HR (Oculus, Wetzlar, Germany) Scheimpflug device (95% LoA − 0.17 to 0.78 mm) [33]. As the phakic IOL size increment is approximately 0.50 mm [34], we can conclude that the CD measurements of LUS-1000 Plus and IOLMaster 700 are clinically interchangeable as indicated by the minor difference (− 0.10 ± 0.14 mm) and the narrow 95% LoA interval (− 0.38 to 0.18 mm).
Nevertheless, this study has some limitations. Elder patients with opaque dioptric media or those with dry eye conditions were not enrolled, which could potentially reduce the repeatability or measurement rate in these cases [35]. Moreover, we excluded certain patient groups, such as those with corneal ectasia or postoperative eyes, which may affect the generalizability of our results to a broader population. Lastly, we only compared this new device with the SS-OCT and future research should therefore focus on evaluating its agreement with other technologies.
Conclusion
The new fully automatic OLCR biometer (LUS-1000 Plus) provided excellent intraobserver repeatability and interobserver reproducibility for biometric measurements, demonstrating excellent agreement with the SS-OCT biometer (IOLMaster 700). These findings validated that the LUS-1000 Plus is a reliable device and can be used interchangeably with the IOLMaster 700.
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Acknowledgements
We thank the participants of the study.
Declarations
Conflict of Interest
Giacomo Savini has received personal fees from Alcon, Johnson & Johnson, SIFI, Thea and Zeiss. Chak Seng Lei, Xinning Yang, Rui Ning, Jinxuan Xiahou, Xinyu Jiang, Domenico Schiano-Lomoriello, Xingtao Zhou, Kexin Li, Jinhai Huang have nothing to disclose.
Ethical Approval
This prospective study adhered to the tenets of the Declaration of Helsinki and received approved from the Institutional Ethics Committee of the Eye and ENT Hospital of Fudan University, Shanghai, China (No. 2021175). Healthy participants were recruited at the Eye and ENT Hospital of Fudan University. Written consent forms were signed by all participants after the study’s purpose and procedures were fully explained.
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Die operative Entfernung oder Bestrahlung von Oligometastasen eines Prostatakarzinoms verlängert das progressionsfreie Überleben deutlich, der Effekt auf das Gesamtüberleben bleibt jedoch unklar.
Laut einer Querschnittstudie leiden rund 7% der in Deutschland lebenden über 16-Jährigen unter chronischen Schmerzen, die ihren Alltag stark beeinträchtigen. Außer biologischen scheinen auch psychische und soziale Faktoren mit sogenanntem High-Impact Chronic Pain assoziiert zu sein.
Radiologische Progressionen ohne vorherige PSA-Wert-Erhöhungen sind mit 10% recht häufig. Dafür sprechen zumindest Ergebnisse einer explorativen Reanalyse von Daten aus der australisch-neuseeländischen ENZAMET-Studie.
Nicht nur Schlaganfälle, sondern auch systemische embolische Ereignisse (SEE) stellen für Menschen mit Vorhofflimmern eine Gefahr dar, wie eine Metaanalyse deutlich macht. Schutz bieten vor allem direkt wirksame orale Antikoagulanzien (DOAK).
