Journal of Refractive Surgery

Original Article Supplemental Data

Agreement Between Two Optical Biometers Based on Large Coherence Length SS-OCT and Scheimpflug Imaging/Partial Coherence Interferometry

Ruixue Tu, MD; Jinjin Yu, MD; Giacomo Savini, MD; Junming Ye, MD; Rui Ning, MD; Jie Xiong, MD; Sisi Chen, MD; Jinhai Huang, MD, PhD

Abstract

PURPOSE:

To evaluate the agreement between measurements obtained with a new optical biometer (Argos; Movu Inc) using large coherence length swept-source optical coherence tomography (SS-OCT) and those obtained with an optical biometer with a rotating Scheimpflug camera, combined with partial coherence interferometry (PCI) (Pentacam AXL; Oculus Optikgeräte GmbH) in adults.

METHODS:

The following measurements were examined and evaluated: axial length, central corneal thickness (CCT), anterior chamber depth (ACD), mean keratometry, J0 and J45 vectors, and corneal diameter. Measurements with the two biometers were conducted in triplicate per instrument in a random order by the same examiner. Paired t tests were employed to compare the difference between the two devices. The Bland-Altman method was implemented to assess their agreement.

RESULTS:

A total of 145 patients were enrolled in the study. The differences between the Scheimpflug/PCI–based biometer and the SS-OCT biometer were as follows: −0.02 ± 0.05 mm for axial length, 1.15 ± 5.79 µm for CCT, −0.04 ± 0.04 mm for ACD, −0.28 ± 0.16 diopters (D) for mean keratometry, 0.01 ± 0.11 D for J0, −0.02 ± 0.10 D for J45, and −1.03 ± 0.62 mm for corneal diameter. Bland-Altman plots showed narrow ranges in axial length, CCT, ACD, mean keratometry, and J0 and J45, which implied excellent agreement between the two biometers. Corneal diameter displayed poor agreement, with a 95% limits of agreement ranging from −2.25 to 0.19 mm.

CONCLUSIONS:

Excellent agreement was established between the measurements provided by the new optical biometer based on SS-OCT and the optical biometer using Scheimpflug imaging and PCI, except for corneal diameter.

[J Refract Surg. 2020;36(7):459–465.]

Abstract

PURPOSE:

To evaluate the agreement between measurements obtained with a new optical biometer (Argos; Movu Inc) using large coherence length swept-source optical coherence tomography (SS-OCT) and those obtained with an optical biometer with a rotating Scheimpflug camera, combined with partial coherence interferometry (PCI) (Pentacam AXL; Oculus Optikgeräte GmbH) in adults.

METHODS:

The following measurements were examined and evaluated: axial length, central corneal thickness (CCT), anterior chamber depth (ACD), mean keratometry, J0 and J45 vectors, and corneal diameter. Measurements with the two biometers were conducted in triplicate per instrument in a random order by the same examiner. Paired t tests were employed to compare the difference between the two devices. The Bland-Altman method was implemented to assess their agreement.

RESULTS:

A total of 145 patients were enrolled in the study. The differences between the Scheimpflug/PCI–based biometer and the SS-OCT biometer were as follows: −0.02 ± 0.05 mm for axial length, 1.15 ± 5.79 µm for CCT, −0.04 ± 0.04 mm for ACD, −0.28 ± 0.16 diopters (D) for mean keratometry, 0.01 ± 0.11 D for J0, −0.02 ± 0.10 D for J45, and −1.03 ± 0.62 mm for corneal diameter. Bland-Altman plots showed narrow ranges in axial length, CCT, ACD, mean keratometry, and J0 and J45, which implied excellent agreement between the two biometers. Corneal diameter displayed poor agreement, with a 95% limits of agreement ranging from −2.25 to 0.19 mm.

CONCLUSIONS:

Excellent agreement was established between the measurements provided by the new optical biometer based on SS-OCT and the optical biometer using Scheimpflug imaging and PCI, except for corneal diameter.

[J Refract Surg. 2020;36(7):459–465.]

Accurate measurements of axial length, central corneal thickness (CCT), anterior chamber depth (ACD), mean keratometry, and corneal diameter are crucial in many clinical settings. These parameters are essential for the calculations by intraocular lens (IOL) calculation formulas and are useful for diagnosing glaucoma and other corneal diseases.1,2 Therefore, technologies that can achieve precise measurements of these parameters are constantly being developed in clinical practice. Examples are partial coherence interferometry (PCI), optical low-coherence reflectometry, optical low-coherence interferometry, and, most recently, swept-source optical coherence tomography (SS-OCT).3,4

The Pentacam AXL (Oculus Optikgeräte GmbH) is a single rotating Scheimpflug camera device combined with optical biometry based on PCI.5 First launched in 2015, it combines anterior segment tomography with axial length measurements. The repeatability of the measurements obtained with the Pentacam HR and the Pentacam AXL has been confirmed.6–8 Previous studies found good agreement between its measurements and those provided by other optical biometers such as the Lenstar LS 900 (Haag-Streit AG) and IOLMaster 700 (Carl Zeiss Meditec AG).8–11

The Argos optical biometer (Movu Inc) is relatively new. It uses a large coherence length SS-OCT with a laser wavelength of 1,060 nm without compromising the axial resolution; additionally, the narrow bandwidth (20 nm) of the wavelength is employed by the device, which improves tissue penetration and image quality.12,13 It is designed to capture a two-dimensional image of the full eye and to measure axial length, CCT, ACD, corneal diameter, lens thickness, pupil size, radii of flat and steep corneal meridians (keratometry), and astigmatism.4,5 A previous study found that the repeatability of the Argos had comparable values and a low variation rate.4

Due to the lack of comprehensive comparison published to date, the aim of this study was to compare the measurements of axial length, CCT, ACD, mean keratometry, J0 and J45 vectors, and corneal diameter obtained with the new Argos large coherence length SS-OCT biometer and the Pentacam AXL Scheimpflug imaging/PCI–based biometer.

Patients and Methods

Patients

In this prospective study, adult participants were enrolled from the Eye Hospital of Wenzhou Medical University, Wenzhou, People's Republic of China. Informed consent was obtained from each patient after the purpose of the investigation had been fully explained. The study was conducted in compliance with the principles of the Declaration of Helsinki and all protocols were approved by the Board of the Eye Hospital of Wenzhou Medical University. The following exclusion criteria were applied: history of ocular trauma, previous ocular surgery, severe corneal or vitreous opacities, significant retinal disease, severe systemic disease, and difficulty to complete the test. The data collected included age (in years), gender, axial length, CCT, ACD, mean keratometry, J0 and J45 vectors, and corneal diameter.

Instruments and Methods

The Pentacam AXL is a rotating Scheimpflug camera combined with PCI-based optical biometry. Its light source is a blue light-emitting diode with a wavelength of 475 nm. The PCI technology is initially employed to measure axial length, followed by measurements of the anterior segment from the anterior corneal surface to the anterior lens surface by a rotating Scheimpflug high-definition camera. The latter records 138,000 data points within two seconds and generates a complete image of the anterior eye segment.8 Any eye movement is detected by a second camera and corrected in the process.5 The Pentacam AXL calculates two ACD values: internal (from the corneal endothelium to the anterior lens surface) and external (from the corneal epithelium to the anterior lens surface). For the purpose of this study, only external ACD was included in our assessments.

The Argos uses large coherence length SS-OCT technology that can provide higher sensitivity for measurements through dense cataracts; it collects a full two-dimensional OCT imaging of the eye at a fast rate of 3,000 A-scans/second. It is designed to measure axial length, ACD, CCT, corneal diameter, and lens thickness based on the Fourier domain technology by light interference using a swept-source laser wavelength of 1,060 nm. Keratometry is obtained from OCT information in combination with a 2.1-mm diameter ring composed of 16 infrared light-emitting diodes.14 The corneal power is obtained with the standard 1.3375 keratometric index. For axial measurements, the Argos uses a refractive index corresponding to each tissue (the refractive index is 1.376 for the cornea, 1.336 for the aqueous and vitreous, and 1.410 for the lens).15 An automatic algorithm evaluates all biometry parameters, and the optical distances are converted into geometric distances using the individual refractive index (rather than a single group refractive index). Patients were instructed to fixate their sight on the internal fixation target of the biometer. To minimize measurement errors, manual adjustment of the parameters from the OCT images is possible and recommended in the presence of outliers.4 The Argos shows whole-eye real-time OCT during the alignment to ensure the performance of successful measurements.

The two biometers were employed for measurements in all patients in a random order by the same examiner (JYe); the measurements were taken within the shortest time period possible. Examinations were performed between 10:00 AM and 5:00 PM. Mean keratometry (K) was calculated as mean K = (steep K+flat K)/2, and the corneal spherocylinder was converted into astigmatism vectors (J0 = [−(steep K-flat K)/2×cos (2×axis)] and J45 = [−(steep K-flat K)/2×sin (2×axis)]).

Statistical Analysis

Statistical analysis was performed using SPSS for Windows software (version 21.0, IBM Corporation). The results of three measurements were calculated and presented as mean ± standard deviation (SD). For agreement assessment, paired t tests, the intraclass correlation coefficient (ICC), and Bland-Altman plots were performed, and 95% limits of agreement (LoA) were calculated.16 This method involved plotting the difference between the two devices against their mean, thereby allowing an assessment of the systematic difference between measurements. The mean difference is the estimated bias, and the SD of the differences measures the random fluctuations of this mean. The range of the ICC is from 0 to 1 and is classified as follows: less than 0.75 = poor, greater than 0.75 = moderate, and greater than 0.9 = excellent. The LoA was defined as the mean ±1.96 SD of the differences between the two measurement techniques, providing an interval within 95% of the differences between measurements, where they were expected to lie. Narrower 95% LoA indicates higher agreement. Comparisons between measurements were performed using a t test, and P values less than .05 were considered statistically significant.17

The minimum sample size was calculated using the PS Power and Sample Size Calculation software (version 3.0; http://biostat.mc.vanderbilt.edu/PowerSample-Size). Considering a previously reported 0.05 mm SD of difference for axial length between the Argos biometer and another PCI optical biometer,4 a sample size of at least 83 patients was calculated to achieve a 0.02 mm difference with a power of 95% and a type 1 error probability of 0.05.

Results

A total of 145 eyes of 145 enrolled patients were subjected to measurements. The mean age of the patients was 37.55 ± 18.21 years (range: 18 to 90 years); 80 (55%) patients were female. The results of the overall study are presented in Table 1. The means ± SD of every biometric parameter are listed for the total number of cases that could be measured. All ocular biometric parameters measurements by the Argos were consistently numerically higher than those obtained by the Pentacam AXL, except for those of CCT and J0 (2.5 mm).

Biometric Measurement Parameters of the New Pentacam AXL Scheimpflug Imaging/Partial Coherence Interferometry Biometer and the Argos SS-OCT Biometer

Table 1:

Biometric Measurement Parameters of the New Pentacam AXL Scheimpflug Imaging/Partial Coherence Interferometry Biometer and the Argos SS-OCT Biometer

The mean difference, paired t test, 95% LoA, and ICC value for the differences between the measurements with the Argos and Pentacam AXL are presented in Table 2. A statistically significant difference (P < .001) was observed in all measurements, except for axial length. However, Bland-Altman plots (Figure A, available in the online version of this article) showed narrow ranges for axial length, CCT, ACD, mean keratometry, and J0 and J45, which implied excellent agreement between the two biometers. On the contrary, a systematic overestimation of corneal diameter measurements by the Argos with respect to the Pentacam AXL was found and confirmed by Bland-Altman plots (Figure B, available in the online version of this article), which revealed poor agreement. Similarly, all measurements had acceptable agreement with an ICC of greater than 0.85 except the corneal diameter (ICC = 0.21).

Mean Difference, Paired t Test, and 95% LoA for Differences Between the New Scheimpflug Imaging/Partial Coherence Interferometry Biometer and the SS-OCT Biometer

Table 2:

Mean Difference, Paired t Test, and 95% LoA for Differences Between the New Scheimpflug Imaging/Partial Coherence Interferometry Biometer and the SS-OCT Biometer

Bland-Altman plots of agreement for the (A) axial length, (B) central corneal thickness, (C) anterior chamber depth, (D) mean keratometry, (E) J0, and (F) J45 between Pentacam AXL (Oculus Optikgeräte GmbH) and Argos (Movu Inc). The mean difference is indicated by a solid blue line, and the 95% limits of agreement is indicated by the dashed red lines. SD = standard deviation; D = diopters

Figure A.

Bland-Altman plots of agreement for the (A) axial length, (B) central corneal thickness, (C) anterior chamber depth, (D) mean keratometry, (E) J0, and (F) J45 between Pentacam AXL (Oculus Optikgeräte GmbH) and Argos (Movu Inc). The mean difference is indicated by a solid blue line, and the 95% limits of agreement is indicated by the dashed red lines. SD = standard deviation; D = diopters

Bland-Altman plots of agreement in corneal diameter between Pentacam AXL (Oculus Optikgeräte GmbH) and Argos (Movu Inc). The mean difference is represented by a solid blue line, and the 95% limits of agreement is represented by the dashed red lines. SD = standard deviation

Figure B.

Bland-Altman plots of agreement in corneal diameter between Pentacam AXL (Oculus Optikgeräte GmbH) and Argos (Movu Inc). The mean difference is represented by a solid blue line, and the 95% limits of agreement is represented by the dashed red lines. SD = standard deviation

Discussion

Obtaining accurate measurements of ocular biometric parameters is crucial for the precision and eventual success of refractive procedures. Several devices on the market can accomplish this objective. For clinical practice, it is important to know whether these devices generate reliable and interchangeable data. Thus, in the current study, for the first time, we investigated the agreement between the measurements provided by a new large coherence length SS-OCT–based biometer and a Scheimpflug imaging/PCI–based biometer using a large sample under identical clinical conditions.

The agreement for all parameters was high, except for corneal diameter. Of note, the mean difference in axial length between the two biometers was just 0.02 mm, with no statistically significant difference and narrow LoA. This implied excellent agreement in the axial length measurements between the two biometers. A similar result was previously reported by Sel et al,8 who found no significant difference in the axial length measurements and a narrow 95% LoA (−0.24 to 0.14 mm) between the Pentacam AXL and another SS-OCT biometer (IOLMaster 700; Carl Zeiss Meditec). However, the 95% LoA of axial length in our study was even lower, ranging from −0.11 to 0.07 mm. Huang et al18 also established a narrow 95% LoA value between another SS-OCT biometer OA-2000 (Tomey) and the IOLMaster 500 (Carl Zeiss Meditec AG), which was from −0.05 to 0.07 mm. Similarly, a narrow 95% LoA was reported between the Argos and IOLMaster 500 (−0.10 to 0.08 mm) by Shammas et al.4 Additionally, Shammas et al4 observed a mean difference between the Argos and Lenstar LS 900 (Haag-Streit AG) of 0.01 mm with a narrow 95% LoA from −0.10 to 0.12 mm. On the other hand, Figure AA clearly shows that axial length values by the Pentacam AXL are higher than those by the Argos in long eyes and lower in short eyes. This difference depends on the use of a single group refractive index in the Pentacam AXL (like in the original IOLMaster) and the adoption of segmented axial length in the Argos.19

Importantly, agreement between the CCT values of the Argos versus Pentacam AXL has not been reported. Kiraly et al20 investigated the agreement between a Scheimpflug imaging system and another SS-OCT–based biometry and found a significant difference of 10.99 ± 7.57 µm with a 95% LoA of −11.33 to 24.67 µm between the instruments. Moreover, Ozyol and Ozyol21 established a significant difference of −5.05 ± 7.67 µm with a 95% LoA from −19.9 to 9.8 µm between the Pentacam HR and IOLMaster 700. However, in the current study, the mean difference between the Argos and Pentacam AXL was the lowest at only 1.15 ± 5.79 µm, and the narrower 95% LoA value was −10.19 to 12.50 µm. The difference between these two devices was significantly smaller than those in the aforementioned reports of Kiraly et al20 and Ozyol and Ozyol.21 Besides, the results of the current study were similar to the findings obtained by Lu et al,22 which showed that the mean difference between the IOLMaster 700 and Sirius Scheimpflug–Placido tomographer (Costruzione Strumenti Oftalmici) was −0.23 ± 6.64 µm with a narrow 95% LoA, from −13.24 to 12.79 µm. These results may be related to the implementation of various measurement techniques due to the use of different devices. The SS-OCT biometer uses a longer wavelength, centered at 1,060 nm, which measures the CCT value from the anterior corneal surfaces to the posterior corneal surfaces. However, the Scheimpflug device identifies the air–tear film surfaces and the posterior corneal surface and transforms the distance between them into CCT, which is based on the elevation points captured by the rotating camera. In addition, the above outcomes might also be attributed to the inconsistent measurement point and different group refractive status. In general, our results are comparable to those mentioned above, which demonstrated the interchangeableness of the devices currently used in clinic.

The mean difference in ACD was small (0.04 mm), with a narrow 95% LoA (−0.12 to 0.03 mm). Similar values were previously reported by Shajari et al,11 who compared the Pentacam AXL and IOLMaster 500 and 700; Sel et al,8 who performed comparisons between the Pentacam AXL and IOLMaster 700; and Ozyol and Ozyol,21 who conducted comparative examination between the Pentacam HR and IOLMaster 700. An ACD difference lower than 0.1 mm is considered unlikely to influence any clinical results. Therefore, the ACD measurements of the Pentacam AXL and Argos can be considered interchangeable.

Compared with the Scheimpflug imaging/PCI–based imaging system, although the mean differences were small (−0.28 ± 0.16 mm), a statistically significant difference of mean keratometry was observed. The results showed that the Scheimpflug imaging/PCI–based imaging system provides slightly flatter mean keratometry values than SS-OCT. Ozyol and Ozyol21 established that in healthy young adults, the Pentacam HR had significantly lower mean keratometry values than the IOLMaster 700 (−0.20 ± 0.09 D). Asena et al23 also found that the mean keratometry values obtained in cataract surgery candidates using the IOLMaster 700 were slightly higher than Scheimpflug imaging system, which is in accordance with Sel et al.8 A study by Lu et al22 showed steeper mean keratometry values obtained by the IOLMaster 700 (0.04 ± 0.11 D) when compared with the Sirius Scheimpflug–Placido tomographer. The results of those studies were similar to the current study. However, the differences were relatively small and can be used interchangeably in clinical practice. Because a mean keratometry difference between the two devices above the range from 0.14 to 0.20 D would yield a different optimized constant for IOL power calculation, caution should be exerted when analyzing the precise IOL power.21

The accuracy of the preoperative J0 and J45 measurements is important for cataract surgery with toric IOLs.24 In a recent study,8 the agreement of measurements of anterior segment parameters between the IOL-Master 700 and one type of Pentacam were evaluated. The authors concluded that J0 and J45 measurements between the Pentacam AXL and IOLMaster 700 had a narrow LoA range of −0.18 to 0.23 and −0.18 to 0.21 D, respectively. The J0 and J45 values of the IOLMaster 700 and Pentacam AXL can be used interchangeably.8 The results were in line with those of Ozyol and Ozyol,21 who found that J0 and J45 values are interchangeable between the Pentacam HR and IOLMaster 700 (−0.10 to 0.24 D; −0.31 to 0.27 D, respectively). Our findings are in line with those of the above studies. We drew a conclusion for the interchangeability between the Argos and Pentacam AXL in which the narrow LoA values of J0 and J45 were −0.20 to 0.21 and −0.23 to 0.18 D.

In this study, we also comparatively assessed the corneal diameter measurements, which revealed a higher mean value of the Argos by approximately 1 mm, a statistically and clinically significant difference. Generally, a difference in the corneal diameter value of 0.50 mm or greater is considered clinically significant.25 Therefore, the agreement in the corneal diameter measurements between the Argos and Pentacam AXL was poor, and the two devices could not be used interchangeably. Relatively poor agreement for corneal diameter measurements has already been reported in previous studies for different devices. For example, Salouti et al26 found that the corneal diameter measurements between the IOLMaster 700 and Pentacam HR was not interchangeable, and the IOLMaster 700 overestimated the corneal diameter value by up to 0.78 mm as compared with that of the Pentacam HR. Similarly, a previous study conducted by Arriola-Villalobos et al27 compared the IOLMaster 700 and Lenstar LS 900 and established that the mean difference in the corneal diameter had a value of 0.01 mm with 95% LoA from −0.84 to 0.82 mm. However, although Lu et al22 found higher corneal diameter values obtained by the IOLMaster 700 than those with a Sirius Scheimpflug–Placido tomographer, the 95% LoA from −0.18 to 0.38 mm was narrower. The accuracy of corneal diameter value—the horizontal diameter between the limbi—mostly depends on the technique that each device uses to define the limbus.26 The Argos uses SS-OCT tomography to distinguish the light and shade interface between the cornea and sclera and then determines the corneal diameter value.18 However, the Pentacam AXL measures the corneal diameter distance by drawing a straight line between two iris landmarks through an iris camera optic that can automatically recognize iris landmarks at the nasal and temporal outlines of the cornea (Figure C, available in the online version of this article).28 This might be the reason for the relatively poor corneal diameter measurements agreement between the Argos and Pentacam AXL.

Differences in the techniques for the measurement of the corneal diameter between Pentacam AXL (Oculus Optikgeräte GmbH) and Argos (Movu Inc). The horizontal red long lines detect the corneal diameter between the nasal and temporal outlines of the cornea by Pentacam AXL (right) and reflect it on the image taken by the Argos. The horizontal red short lines denote the corneal diameter between the two distal lines by Argos (left). ab = corneal diameter by the Pentacam AXL; cd = corneal diameter by the Argos

Figure C.

Differences in the techniques for the measurement of the corneal diameter between Pentacam AXL (Oculus Optikgeräte GmbH) and Argos (Movu Inc). The horizontal red long lines detect the corneal diameter between the nasal and temporal outlines of the cornea by Pentacam AXL (right) and reflect it on the image taken by the Argos. The horizontal red short lines denote the corneal diameter between the two distal lines by Argos (left). ab = corneal diameter by the Pentacam AXL; cd = corneal diameter by the Argos

The Argos is designed to capture a two-dimensional image of the whole eye, whereas the Scheimpflug system is designed to capture a three-dimensional scan of the anterior segment. The latter can provide a more detailed analysis of the cornea and anterior chamber, as previously demonstrated by several studies.29–32 From a refractive point of view, the ability of Scheimpflug cameras to measure the posterior corneal astigmatism can be an advantage for toric IOL calculation.

The current study has some limitations. First, we did not include patients with other eye diseases such as keratoconus or pellucid marginal degeneration. Therefore, further studies are necessary to assess the agreement of these devices for such pathologies. Second, the interval of the axial length measurements (21.34 to 27.68 mm) was relatively narrow, and thus a larger interval for different results may be expected. These limitations will be addressed in a future study.

Except for the lack of significant variations in the axial length values, the CCT, ACD, mean keratometry, J0 and J45, and corneal diameter values of the new large coherence length SS-OCT–based biometry and the Scheimpflug/PCI–based biometer showed a significant difference statistically (P < .001), but not clinically. Furthermore, both the Pentacam AXL and Argos had pronounced agreement in the axial length, CCT, ACD, mean keratometry, and J0 and J45 measurements and can thus be considered interchangeable for clinical use. Nonetheless, the Pentacam AXL might have overestimated the corneal diameter value as compared with that of the Argos, and the non-interchangeability in this respect between the two devices is not surprising. In addition, more investigations are to be undertaken aiming to elucidate the agreement between the two optical methods in their application in the diagnosis of a wide range of ocular diseases.

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Biometric Measurement Parameters of the New Pentacam AXL Scheimpflug Imaging/Partial Coherence Interferometry Biometer and the Argos SS-OCT Biometer

ParameterPentacam AXLArgos


Mean ± SDRangeMean ± SDRange
AL (mm)24.74 ± 1.4521.34 to 27.6824.76 ± 1.4221.49 to 27.63
CCT (µm)536.47 ± 30.00472.00 to 613.67535.31 ± 30.13469.67 to 619.33
ACD (mm)3.51 ± 0.442.42 to 4.313.56 ± 0.432.51 to 4.33
Km (2.5 mm)43.44 ± 1.4039.85 to 46.8343.72 ± 1.3940.16 to 47.19
J0 (2.5 mm)−0.34 ± 0.43−1.65 to 0.68−0.35 ± 0.47−1.91 to 0.67
J45 (2.5 mm)−0.01 ± 0.19−0.61 to 0.800.02 ± 0.20−0.72 to 0.73
CD (mm)11.59 ± 0.3810.57 to 12.7012.63 ± 0.7910.32 to 14.07

Mean Difference, Paired t Test, and 95% LoA for Differences Between the New Scheimpflug Imaging/Partial Coherence Interferometry Biometer and the SS-OCT Biometer

ParameterMean ± SDP95% LoAICC
AL (mm)−0.02 ± 0.05.125−0.11 to 0.070.999
CCT (µm)1.15 ± 5.79< .001−10.19 to 12.500.981
ACD (mm)−0.04 ± 0.04< .001−0.12 to 0.030.991
Km (2.5 mm)−0.28 ± 0.16< .001−0.58 to 0.030.974
J0 (D)0.01 ± 0.11< .001−0.20 to 0.210.972
J45 (D)−0.02 ± 0.10< .001−0.23 to 0.180.858
CD (mm)−1.03 ± 0.62< .001−2.25 to 0.190.21
Authors

From the School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China (RT, JYu, JYe, RN, JX, SC, JH); Key Laboratory of Vision Science, Ministry of Health People's Republic of China, Wenzhou, Zhejiang, People's Republic of China (RT, SC, JH); and IRCCS G.B. Bietti Foundation, Rome, Italy (GS).

Supported in part by the Zhejiang Provincial Key Research and Development Program (Grant No. 2018C03012); Medical and Health Science and Technology Program of Zhejiang Province (Grant No. 2019KY111); Foundation of Wenzhou City Science & Technology Bureau (Grant No. Y20180174); and Zhejiang Provincial High-level Talents Program (Grant No. 2017-102). The contribution of IRCCS G.B. Bietti Foundation was supported by Fondazione Roma and the Italian Ministry of Health.

The authors have no financial or proprietary interest in the materials presented herein.

Drs. Tu and Yu contributed equally to this work and should be considered as equal first authors.

AUTHOR CONTRIBUTIONS

Study concept and design (RT, JYu, SC, JH); data collection (JYe, RN, JX); analysis and interpretation of data (GS); writing the manuscript (JYu, JYe, RN); critical revision of the manuscript (RT, JYu, GS, JX, SC, JH); statistical expertise (GS); administrative, technical, or material support (RT, SC, JH); supervision (RT, SC, JH)

Correspondence: Sisi Chen, MD ( 248111700@qq.com), and Jinhai Huang, MD, PhD ( vip999vip@163.com), Eye Hospital of Wenzhou Medical University, 270 West Xueyuan Road, Wenzhou, Zhejiang 325027, People's Republic of China.

Received: September 21, 2019
Accepted: April 20, 2020

10.3928/1081597X-20200420-02

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