In healthy eyes, the accuracy and interchangeability of corneal tomography measurements obtained by Galilei G6 and Pentacom HR systems are compared

In healthy eyes, the accuracy and interchangeability of corneal tomography measurements obtained by Galilei G6 and Pentacom HR systems are compared | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article In healthy eyes, the accuracy and interchangeability of corneal tomography measurements obtained by Galilei G6 and Pentacom HR systems are compared Marrwan Mohammed, Mustafa Tawfeeq Halboos, Noor Khamees Hamad This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8026210/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose: To compare the accuracy and interchangeability of anterior segment measurements obtained using the Galilei G6 and Pentacam HR systems in healthy eyes. Methods: This cross-sectional study involved 51 right eyes from 51 healthy participants (age range: 19–47 years). Three consecutive scans were performed on each eye using both systems. Key parameters measured included keratometry (K1, K2), central corneal thickness (CCT), anterior chamber depth (ACD), and corneal volume (CV). Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to assess measurement agreement. Results: The mean age of participants was 29.0 ± 8.4 (range,19-47)years(male/female =20/31). Significant differences were observed in K1 (P = 0.038) and CCT (P < 0.001), while ACD showed no statistically significant difference (P = 0.177). Bland–Altman plots revealed wide limits of agreement for CCT and keratometry, indicating limited agreement that may affect clinical interchangeability for these parameters. K1 measurements were interchangeable within ±0.25 D (clinically acceptable margin), while CCT measurements showed differences exceeding the ±10 μm clinically acceptable threshold. ACD showed moderate variability, suggesting limited interchangeability between the devices for this parameter. The results highlight the importance of considering device-specific measurements for clinical decision-making. Conclusion: K1 measurements from the Pentacam HR and Galilei G6 systems showed close agreement within ±0.25 D in healthy eyes, suggesting reasonable consistency for clinical assessments. However, differences in CCT and ACD measurements exceeded clinically acceptable limits, indicating that these parameters should not be used interchangeably. As the study was limited to healthy eyes, the findings should be interpreted with caution and may not directly apply to patients with corneal irregularities or a history of ocular surgery. Future studies should investigate the performance of these devices in more diverse patient populations to assess broader clinical applicability. Scheimpflug imaging Pentacam HR Galilei G6 CCT Interchangeability Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Accurate measurement of anterior segment parameters is critical for screening candidates for cataract and corneal refractive surgery, and plays a key role in predicting postoperative outcomes and complications ( 1 – 5 ). It is also important to choose the type of surgery or predict postoperative complications( 6 ). Corneal topography, particularly corneal tomography, is an advanced optical method used in clinical practice to assess both the anterior and posterior corneal surfaces, offering 3D maps of the cornea( 7 ). This technology has proven invaluable in detecting and monitoring the progression of ectatic corneal diseases, such as keratoconus( 7 ). Several technologies for corneal imaging systems are available to analyze anterior segment parameters, including slit-scanning tomography, anterior segment optical coherence tomography, and rotating Scheimpflug cameras. ( 8 ) Scheimpflug technology is one of the most accurate methods in clinical practice among all corneal tomography diagnostic methods. In response to the previous study by Moshirfar et al. (2022)(35), which compared the Galilei G6 and Pentacam AXL, we acknowledge that the Pentacam AXL is a more recent version of the Pentacam technology, differing in both hardware configuration and measurement area compared to the Pentacam HR. While the AXL model uses a larger central measurement area and features improvements in software and accuracy, the Pentacam HR remains a widely used and clinically relevant model for anterior segment imaging. Our study specifically evaluates the Pentacam HR and Galilei G6, providing insights into their interchangeability and measurement reliability in healthy eyes, which is a distinct focus from the AXL-Galilei comparison. We believe this comparative analysis offers valuable data for clinicians utilizing the Pentacam HR in everyday practice and highlights the need for further research with other corneal pathologies and surgical conditions. This work contributes to the understanding of these devices' performance and supports their clinical applicability( 9 ). The increasing popularity of corneal tomography systems, such as the Pentacam HR (single-rotating camera) and the Galilei G6 (dual-rotating camera with Placido disc), reflects their ability to provide highly accurate measurements of corneal thickness and curvature( 10 , 11 ). Therefore, while the Pentacam HR is a single-rotating camera, the Galilei G6 is a dual-rotating camera combined with a Placido disk, and its hardware configuration differs. ( 12 ). Previous studies demonstrated excellent repeatability and reproducibility for measurements of the Pentacam instrument. ( 13 – 16 ) While some reports indicate the less reliable measurements towards the periphery of the cornea,( 17 ) most practitioners already know their measurements are superior to findings of the conventional method of Placido-based corneal topography in diagnosing peripheral corneal diseases. ( 18 , 19 ) In comparison to other corneal tomography imaging systems, Pentacam showed excellent intra-device precision; however, the inter-device measurement repeatability was conflicting. ( 16 , 20 , 21 ) On the other hand, previous reports prove Galilei's high accuracy and reproducibility in measuring anterior segment parameters. ( 21 – 23 ) One of the most noticeable superiorities of the Galilei device compared to the other corneal tomography analyzers is the software's ability to minimize motion errors via eye motion and a cyclotorsion corrective system. ( 24 , 25 ). While the Pentacam HR has been widely studied for its reliability and reproducibility, there remains limited research directly comparing its measurements with those from the newer Galilei G6 system. This study aims to fill this gap by evaluating the interchangeability and measurement reliability between these two systems in healthy eyes, with implications for broader clinical use. Future research should consider expanding the study population to include individuals with corneal ectasia, post-refractive surgery patients, and other pathologies to enhance the generalizability of the findings. Patients and methods In this cross-sectional study, the medical records of 51 right eyes from 51 healthy participants, aged 18–50 years, who visited Hilla Surgery Hospital for preoperative refractive surgery assessments between January and March 2022, were retrospectively analyzed. All participants had normal corneal topography and no history of ocular disease or previous surgery. Eyes with unreliable measurements, such as those failing quality control or falling outside the acceptable range, were excluded to ensure that only high-quality data were used for comparison between the two devices. To ensure clinical relevance, future studies should expand the sample to include patients who have undergone refractive surgery or those with conditions such as keratoconus, to further assess device interchangeability in different patient populations. Ethical approval for this study (Ethical Committee OPT.2/2025) was provided by the Ethical Committee of Mustaqbal College University of Medical Sciences on 28 September 2025. The measurements were performed using both the Galilei G6 (Ziemer Ophthalmic Systems, Port, Switzerland) and Pentacam HR (Oculus, Wetzlar, Germany) systems. To minimize inter-device variability, measurements were taken in a fixed order with a brief interval between devices (≤ 15 minutes). To align measurement protocols, the central 3 mm area was used for Pentacam HR, while the central 4 mm area was analyzed for the Galilei G6. Additionally, the study should ideally include repeatability metrics such as within-device standard deviation and test-retest reliability to provide a more complete picture of each device's precision. Sample Size Justification: Sample size determination was based on a power analysis using G*Power software. Assuming a medium effect size (Cohen’s d = 0.5) for the comparison between Pentacam HR and Galilei G6, with an alpha level of 0.05 and 80% power, the analysis indicated that a sample size of 34 participants (68 eyes) would be required to detect a statistically significant difference. Given that our study includes 51 healthy eyes (approximately 51 participants), this sample size is sufficient to detect meaningful differences between the devices, ensuring robust statistical power. This was consistent with previous studies in this field, which have used similar sample sizes for similar analyses. Examination protocols: The study was conducted on 51 right eyes from 51 healthy individuals, with a mean age of 29.0 ± 8.4 years (range, 19–47). Of these, 31 (60.8%) were female and 20 (39.2%) were male. While the study focused on healthy eyes, it is important to note that the findings may not be applicable to individuals with corneal pathologies or post-surgical conditions. Further studies involving patients with conditions such as keratoconus or those who have undergone refractive surgery are necessary to assess the broader applicability of these findings. A standard examination protocol was used to obtain measurements on each instrument. First, a Pentacam HR was performed, followed by a Galilei G6 measurement, which was to be completed within 15 minutes of the Pentacam HR test. Before the test, the eyes were blinked to ensure a uniform tear layer. Then, each eye was measured three times, and the average value was used for analysis. Both Galilei G6 and Pentacam HR provide quality information, and cases that were not 'OK' or 'measurement successful' were excluded from the analysis. For Galilei G6, the anterior and posterior corneal power was measured in the central 4 mm area (simulated keratometry). In the case of Pentacam HR, the central 3 mm area (simulated keratometry) and central 4 mm area (sagittal [axial] power) were analyzed by measuring the corneal refractive power of the anterior and posterior surfaces. This difference in the central measurement area arises from the distinct hardware configurations and imaging techniques used by the devices. Pentacam HR uses a single rotating camera, while Galilei G6 employs dual rotating cameras with a Placido disc, which may introduce variability in measurements at the corneal periphery. Anterior chamber depth(ACD) was defined as the distance from the corneal endothelium to the front of the lens ( 26 , 27 ). Accurate evaluation of the anterior segment is crucial in preoperative assessments for corneal refractive surgeries. This study compared two commonly used corneal tomography systems, Pentacam HR and Galilei G6, to assess their reliability and interchangeability in healthy eyes. Although both devices use Scheimpflug technology, significant differences in their measurement protocols and hardware (e.g., single versus dual camera systems) led to discrepancies in certain parameters, particularly keratometry and central corneal thickness (CCT). Our findings indicate that while both devices provide reliable measurements, they cannot be considered interchangeable for most anterior segment parameters. The wide limits of agreement observed for keratometry and CCT suggest that clinical decisions based solely on measurements from either device could lead to discrepancies in surgical planning and patient management. Furthermore, the 95% limits of agreement for many parameters exceeded clinically acceptable thresholds, underscoring the importance of considering device-specific measurements when making clinical decisions. Measurement Aperture Alignment and Sensitivity Analysis: To mitigate potential systematic biases arising from differences in the measurement apertures of the two devices, we aligned the measurement areas as much as possible. For the Galilei G6, the anterior and posterior corneal power was measured using the central 4 mm area (simulated keratometry), while Pentacam HR utilized the central 3 mm area for simulated keratometry and the central 4 mm area for sagittal (axial) power. Given these differences in aperture sizes, a sensitivity analysis was conducted to evaluate the impact of varying measurement areas (3 mm vs. 4 mm) on key parameters, including keratometry (K), central corneal thickness (CCT), and anterior chamber depth (ACD). This analysis was essential to assess whether the aperture size influenced the comparative results between the devices. The sensitivity analysis helped ensure that the observed differences in measurements were not solely attributable to the varying aperture sizes but reflected inherent discrepancies in the devices’ measurement methods and hardware configurations. By performing this additional analysis, we aimed to provide a more robust evaluation of the interchangeability of the two devices and clarify the potential sources of bias. Clinical Equivalence/Interchangeability Thresholds: In defining clinically acceptable thresholds, we considered values commonly used in clinical practice for refractive surgery planning and post-operative evaluations. For example, keratometry values within ± 0.25 D are generally considered clinically acceptable for the assessment of corneal curvature in surgical planning. Similarly, ± 0.10 mm for anterior chamber depth (ACD) and ± 10 µm for central corneal thickness (CCT) are well-established thresholds for evaluating corneal health and surgical suitability. Statistical analysis: Statistical analysis was performed using SPSS 26.0 (SPSS Inc., Chicago, IL, USA). A paired t-test was used to compare the differences in average measured values between the two equipment types. The intraclass correlation coefficient (ICC) was calculated to evaluate the reliability of the different tomographic indices between the Pentacam HR and Galilei G6. Although ICC was used as a measure of repeatability in this study, alternative methods such as the coefficient of variation or within-subject standard deviation should be considered in future work to better align with current international standards. Additionally, the correlation coefficient between measurement methods was obtained using Pearson correlation, and p < 0.05 was considered a significant difference. The degree of agreement between the anterior segment measurements obtained by the two devices was expressed as the 95% limits of agreement (lower limit of agreement, upper limit of agreement) using Bland-Altman plot analysis( 28 ). Medcalc® software version 19.0.4 was used for drawing Bland–Altman plots. Results The study was conducted on 51 right eyes from 51 healthy individuals, with a mean age of 29.0 ± 8.4 years (range, 19–47). Of these, 31 (60.8%) were female and 20 (39.2%) were male. Comparison of keratometry and Q-value of anterior and posterior corneal surfaces between Pentacam HR and Galilei G6 is reported in Table 1 . Based on the results obtained from this table, the mean flat K measured by Pentacam HR on the anterior corneal surface was significantly higher than that of Galilei G6 (P = 0.038). Also, in the posterior corneal surface, the mean of flat and steep K measurements was significantly different (P < 0.001). The mean amounts of CCT, TCT, PD, CV, and ACV showed significant differences between the two tomography devices. The measurements for ACD and TCT revealed mean differences between the Pentacam HR and Galilei G6 of 0.05 mm and 23.84 µm, respectively. A comparison of pachymetric indices, including ACD, PD, ACA, CV, and ACV, between the Pentacam HR and Galilei G6 is presented in Table 2 . Bland–Altman plot for anterior and posterior flat K and steep K measurements comparing Pentacam HR and Galilei G6 are shown in Fig. 1 . Additionally, the scatter plots of these parameters, comparing two topography devices, are displayed in Fig. 2 . In Fig. 3 , Bland–Altman plots for TCT and ACD comparing Pentacam HR and Galilei G6 are shown. Additionally, Fig. 4 presents scatter plots to compare TCT and ACD between the two topography devices. Table 1 Comparison of keratometry and asphericity of anterior and posterior corneal surfaces between Pentacam HR (Oculus, Wetzlar, Germany) and Galilei G6 (Ziemer Group, Port, Switzerland). Devices Mean ± SD Minimum Maximum Correlation ICC Difference of mean ± SD** 95% CI of P -value* differences of means Lower Upper Anterior Flat K (D) Pentacam HR 43.19 ± 1.37 40.3 45.8 0.964 0.981 -0.11 ± 0.37 -0.21 -0.01 0.038 Galilei G6 43.30 ± 1.33 40.33 45.85 Steep K (D) Pentacam HR 44.47 ± 1.64 40.44 50.1 0.598 0.737 0.20 ± 1.36 -0.18 0.59 0.293 Galilei G6 44.26 ± 1.32 41.72 46.66 Q-value Pentacam HR -0.32 ± 0.14 -1.09 -0.14 -0.009 -0.015 -0.20 ± 0.30 -0.28 -0.11 < 0.001 Galilei G6 -0.13 ± 0.26 -0.68 0.59 Posterior Flat K (D) Pentacam HR -6.15 ± 0.20 -6.5 -5.7 0.418 0.586 -0.12 ± 0.23 -0.19 -0.06 < 0.001 Galilei G6 -6.02 ± 0.22 -6.57 -5.59 Steep K (D) Pentacam HR -6.50 ± 0.29 -7.4 -6 0.48 0.644 -0.21 ± 0.28 -0.28 -0.13 < 0.001 Galilei G6 -6.29 ± 0.25 -6.86 -5.92 Q-value Pentacam HR -0.29 ± 0.15 -0.91 -0.03 -0.061 0.087 -0.18 ± 0.42 -0.30 -0.06 0.003 Galilei G6 -0.11 ± 0.39 -1.2 0.85 *Based on paired samples t-test. ** Differences in the mean values are calculated by subtracting measurements of Pentacam HR from Galilei G6. N: Number, ICC: intraclass correlation coefficient. Table 2 Comparison of pachymetric at pupil center, anterior chamber depth, anterior chamber angle, pupil diameter, corneal volume, and anterior chamber volume between Pentacam HR (Oculus, Wetzlar, Germany) and Galilei G6 (Ziemer Group, Port, Switzerland). Devices Mean ± SD Minimum Maximum Correlation ICC Difference of mean ± SD** 95% CI of P -value* differences of means Lower Upper Pupil center pachymetry (mm) Pentacam HR 529.25 ± 23.81 464 565 0.28 0.431 -6.90 ± 31.86 -15.86 2.06 0.128 Galilei G6 536.16 ± 28.86 449 596 CCT (µm) Pentacam HR 530.49 ± 24.79 463 570 0.105 0.181 -23.84 ± 40.40 -35.21 -12.48 < 0.001 Galilei G6 554.33 ± 34.61 498 642 TCT (µm) Pentacam HR 524.59 ± 24.55 460 563 0.373 0.536 -2.75 ± 30.72 -11.39 5.9 0.526 Galilei G6 527.33 ± 29.76 429 580 ACD (mm) Pentacam HR 3.15 ± 0.30 2.28 3.9 0.584 0.732 -0.05 ± 0.26 -0.12 0.02 0.177 Galilei G6 3.20 ± 0.26 2.5 3.91 Pupil diameter (mm) Pentacam HR 2.98 ± 0.87 1.93 7.19 0.247 -0.154 -0.47 ± 1.11 -0.78 -0.16 0.004 Galilei G6 3.45 ± 0.94 2.36 7.56 ACA (degree) Pentacam HR 40.68 ± 5.03 24.1 49.3 0.539 0.673 0.62 ± 4.31 -0.61 1.84 0.318 Galilei G6 40.06 ± 3.54 29.7 45.8 Corneal volume (mm 3 ) Pentacam HR 59.98 ± 2.45 11.09 12.9 -0.067 -0.043 12.90 ± 15.60 8.42 17.38 < 0.001 Galilei G6 47.08 ± 15.24 53.3 64.3 Anterior chamber volume (mm 3 ) Pentacam HR 189.18 ± 24.18 27.8 63.9 0.725 0.837 27.63 ± 17.09 22.83 32.44 < 0.001 Galilei G6 161.54 ± 21.42 123 255 *Based on paired samples t-test. ** Difference of the mean values calculated by subtracting measurements of Pentacam HR from Galilei G6. N: Number, ICC: intraclass correlation coefficient, CCT: central corneal thickness, TCT: thinnest corneal thickness, ACD: anterior chamber depth, ACA: anterior chamber angle. Discussion A precise evaluation of the anterior segment is of paramount importance before performing corneal refractive surgery procedures. The Galilei G6 and Pentacam HR, which are types of rotating Scheimpflug cameras, are noncontact methods and take less than two seconds to measure anterior segment parameters. ( 11 ) However, discrepancies have been reported regarding the comparability of their measurements, and few studies have directly compared anterior segment values obtained from the two devices. The observed differences between Pentacam HR and Galilei G6 measurements can largely be attributed to variations in hardware and optical design. The Pentacam HR reconstructs the anterior segment using approximately 25,000 true elevation data points with a single rotating Scheimpflug camera, while the Galilei G6 employs dual rotating cameras with an integrated Placido disc, capturing more than 120,000 data points. This configuration allows Galilei G6 to correct for minor fixation errors and compensate for eye motion, potentially influencing its measurement outputs. Additionally, Galilei G6 measures corneal power in a 4 mm central zone, whereas Pentacam HR typically analyzes the central 3 mm zone. These differences in measurement area and hardware configuration may contribute to the observed variability between devices.. In the present study, the ACD measured by Galilei G6 was 0.05 mm deeper than that measured by Pentacam HR, showing a similar trend to previous studies( 12 , 21 , 29 ). The 95% LoA of Galilei G6 with Pentacam HR in the measurement of the thinnest corneal thickness was − 0.56 and + 0.46 mm. Although the mean difference in measuring ACD was not statistically significant, the two devices showed moderate reliability (ICC = 0.732). Aramberri et al. compared ACD measured using Galilei G2 and Pentacam HR in 35 normal adult eyes. The ACD measured by Galilei G2 was 0.10 mm deeper than that measured by Pentacam HR, a statistically significant difference. ( 12 ) In addition, Hernández-Camarena et al. reported that the ACD measured by Pentacam HR and Galilei G2 was 3.10 mm and 3.60 mm, respectively, showing a marginally significant difference (p = 0.059). ( 21 ) They concluded that ACD measurements by the two devices could not be used interchangeably. We also found that Pentacam HR and Galilei G6 had moderate reliability and correlation in measuring ACD. In addition, the Bland-Altman analysis showed wide limits (-0.56 to 0.46 mm) and clinically relevant differences in 95% LoA for ACD measurements. Therefore, Pentacam HR and Galilei G6 may not be suitable for interchangeable use in all clinical contexts when assessing ACD Inaccurate interpretation of anterior segment parameters can have significant consequences in clinical practice. In another study, Han et al. found that the ACD measured using Galilei G2 and Pentacam were 3.23 mm and 3.22 mm, respectively, showing no significant difference between the two devices. ( 29 ) In line with the present study, they also concluded that the LoA between the two instruments were wide; therefore, it was mentioned that the measured value could not be used interchangeably. Pachymetric measurements, including central corneal thickness (CCT), have become an important tomography parameter. It is considered an essential measurement in the preoperative evaluation of candidates for refractive surgery. In addition, pachymetry of the entire corneal tissue, with identification of the thinnest point, is useful as it provides information for diagnosing and monitoring ectatic corneal disease. ( 30 ) According to the findings of the present study, the mean values of CCT obtained from Pentacam HR and Galilei G6 were 530.49 ± 24.79 and 554.33 ± 34.61, respectively. Accordingly, the CCT was measured to be 23.84 µm thicker in Galilei G6, showing a statistically significant difference. The 95% LoA of Galilei G6 with Pentacam HR in the measurement of the thinnest corneal thickness was − 63 and + 57.5 µm. In a prospective study, Crawford et al. compared the CCT measured using Galilei and Pentacam in normal adults with an average age of 38.0 years. ( 31 ) The authors asserted that the LoA was wide, from − 11 to 47 µm; Hence, these measurements may not be suitable for interchangeable use in clinical evaluations. On the other hand, Aramberri et al. reported that the accuracy of CCT measured with Galilei was higher than that of Pentacam, as Galilei corrected for the center deviation of the x-y axis using two Scheimpflug cameras. However, the difference in central corneal thickness measured with the two devices was 2.76 µm. ( 12 ) Clinically, it is not a large value in microns; therefore, they can be used interchangeably in clinical practice. The authors assessed the intraclass correlation coefficient and within-subject standard deviation for corneal curvature, astigmatism, and CCT measured by Galilei G2 and Pentacam HR ( 12 ) by calculating simK and corneal astigmatism. It was suggested that Pentacam showed higher reproducibility between and within measurers. Galilei measured corneal thickness with greater accuracy and high reproducibility. In the study by Han et al., central corneal thickness was measured using Galilei, Pentacam, and Lenstar in normal adults and compared between the groups. ( 29 ) In contrast, they reported that it is a wide LoA that cannot be used in clinical practice. In the present study, the measured value of Galilei G6 was measured to be thicker than that of Pentacam HR. In a prospective study, Anayol et al. investigated the agreement of three Scheimpflug-based devices (Pentacam HR, Sirius, and Galilei) for measuring anterior segment parameters in healthy individuals. ( 32 ) Regarding CCT, they reported that there was a significant difference between the three devices (P < 0.001), with the Galilei having the highest measurements compared to Pentacam and Sirius. In addition, Pentacam and Sirius showed better agreement with each other than with Galilei. Also, similar findings were observed for TCT measurements. They reported that the differences between the CCT and TCT measurements of Pentacam and Galilei were − 13.93 and − 5.5 µm, respectively. In terms of corneal curvature, they reported that Galilei and Sirius's devices displayed superior agreement with each other than with Pentacam. As a result, the difference is expected to be large enough to be considered clinically relevant. Additionally, the two devices demonstrated lower correlation coefficients indicating reduced reliability in measuring CCT data. Therefore, it is thought that the two Scheimpflug-based devices cannot be used interchangeably for CCT measurements. Notably, our findings differed from those of Jahadi Hosseini et al., who reported good agreement between two Scheimpflug devices (Galilei and Pentacam) in measuring CCT data. ( 33 ) Among the different simulated keratometry readings provided by the two devices, only the anterior flat K reading showed excellent reliability (ICC = 0.981) and a strong correlation (r = 0.964) between the two devices. Other keratometry measurements showed moderate reliability between the two devices. In addition, the 95% LoA of Galilei G6 and Pentacam HR for all keratometry readings was large enough to be considered clinically significant. Broad limits of agreement suggest that, while average values may appear similar, individual measurements can differ significantly, often exceeding clinically acceptable thresholds for surgical planning or diagnosis. Thus, using these devices interchangeably without considering this variability could jeopardise patient safety and affect clinical results. Although the two investigated instruments operate on almost the same principle, this does not guarantee that they can be used interchangeably. The keratometry powers obtained by Galilei G6 and Pentacam HR are reported to differ in healthy eyes. ( 32 ) As a result, it is thought that it may be challenging to use the two devices interchangeably in routine clinical settings. The reason for the difference in anterior segment parameters measured by Galilei G6 and Pentacam HR can be attributed to differences in hardware between the two devices. Pentacam HR reconstructs the image of the anterior segment three-dimensionally using 25,000 true elevation data points16. At the same time, the camera rotates 360° around the eye's optical axes. On the other hand, the Galilei G6, unlike the Pentacam HR, obtains corneal measurements by correcting the image obtained through the Placido disc ( 26 ) and directly measures the anterior segment (cornea, iris, pupil, anterior chamber depth, lens) using more than 122,000 data points. It analyzes the shape and thickness of the cornea, as well as the size of the pupil. It simultaneously records two Scheimpflug camera images to correct minor fixation errors that may occur during the examination. ( 34 ) Furthermore, Galilei G6 fundamentally provides corneal power in the central 4 mm area, and Pentacam HR provides corneal power in the central 3 mm area. Differences in the measurement area can affect corneal measurements. The incorporation of a dual Scheimpflug system in Galilei may imply that it provides more accurate measurements; however, previous comparisons have not outlined higher superiority over single Scheimpflug technology. ( 26 ) Similarly, we did not observe any superiority of Galilei G6 over the Pentacam HR. The present study suffers from some limitations. First, we did not include all anterior segment parameters provided by the two devices. Second, the measurements of other topography systems with different imaging technologies were not compared. Third, we only included healthy eyes; further studies should be planned to compare other patient groups, including those with corneal ectasia, corneal scarring, and those undergoing corneal refractive surgeries. Limitations of this study include the relatively small sample size, which may limit the generalizability of the findings. To improve statistical power and obtain more robust data, future studies should aim to include larger sample sizes. Additionally, expanding the study population to include individuals with conditions such as keratoconus or those who have undergone refractive surgery would provide further insights into the reliability of these devices in diverse clinical settings. Another limitation is that the study did not perform repeatability or reproducibility testing within each device, which is essential to fully understand measurement reliability. Further studies should be planned to compare other patient groups, including those with corneal ectasia, corneal scarring, and those undergoing corneal refractive surgeries. Future Research Directions: To further assess the clinical applicability of the findings, future studies should include post-refractive surgery eyes and patients with keratoconus. These populations would provide a more comprehensive understanding of the performance and interchangeability of the Galilei G6 and Pentacam HR systems in various clinical scenarios. Conclusions In conclusion, K1 measurements from Pentacam HR and Galilei G6 demonstrated close agreement within ± 0.25 D in healthy eyes. However, as the study population did not include eyes with corneal irregularities or prior surgery, these findings should be interpreted with caution when applied to clinical or surgical planning. However, CCT and ACD measurements differ significantly between the two devices, with differences exceeding the clinically acceptable thresholds of ± 10 µm for CCT and ± 0.10 mm for ACD, making these parameters unsuitable for interchangeable use in clinical decisions. The results of this study are limited to healthy eyes and may not apply to patients with irregular corneas, post-operative corneas, or other pathologies such as keratoconus. Further studies are needed to explore the performance of these devices in more diverse populations to understand their applicability in clinical settings for a wider range of patients. Abbreviations K1 Flat keratometry K2 Steep keratometry CCT Central corneal thickness ACD Anterior chamber depth CV Corneal volume ICC Intraclass correlation coefficient LoA Limits of agreement Declarations Conflicting Interest: The authors declare that there is no conflict of interest. Funding information: The authors did not receive financial support from public or private sources. The authors have no financial or proprietary interest in a product, method, or material described herein. Ethics approval and consent to participate Ethical approval for this study was obtained from the Ethical Committee of Mustaqbal University College of Medical Sciences (Approval No.: OPT.2/2025; Date: 28 September 2025). All participants were informed about the purpose of the study, and written informed consent was obtained from each participant prior to data collection, in accordance with the Declaration of Helsinki. Consent for publication Not applicable. Availability of data and materials The datasets used and analyzed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding The authors did not receive financial support from public or private sources. The authors have no financial or proprietary interest in a product, method, or material described in this article. Authors’ contributions MHM conceived and designed the study, performed data analysis, and drafted the manuscript. MTH contributed to data interpretation, methodology validation, and critical revision of the manuscript. NKH assisted in data collection and statistical analysis. All authors read and approved the final manuscript. Availability of data and materials The datasets generated and/or analyzed during the current study are not publicly available due to patient confidentiality and institutional data protection policies, but are available from the corresponding author on reasonable request. Acknowledgements The authors would like to express their sincere gratitude to the administration of Al Mustaqbal University for their continuous guidance and support throughout the preparation of this work. References Moshirfar M, Duong A, Ronquillo Y. Corneal imaging. StatPearls [Internet]: StatPearls Publishing; 2021. Khoramnia R, Rabsilber TM, Auffarth GU. 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Sinjab MM. Corneal Tomography in Clinical Practice (Pentacam System): Basics & Clinical Interpretation. Jaypee Brothers Medical; 2018. Wegener A, Laser-Junga H. Photography of the anterior eye segment according to Scheimpflug's principle: options and limitations–a review. Clin Exp Ophthalmol. 2009;37(1):144–54. Youn SM, Lim SH, Lee HY. Measurement Comparison of Anterior Segment Parameters between AL-Scan (R) and Pentacam (R). J Korean Ophthalmological Soc. 2014;55(6):801–8. Chen D, Lam AK. Intrasession and intersession repeatability of the Pentacam system on posterior corneal assessment in the normal human eye. J Cataract Refractive Surg. 2007;33(3):448–54. Aramberri J, Araiz L, Garcia A, Illarramendi I, Olmos J, Oyanarte I, et al. Dual versus single Scheimpflug camera for anterior segment analysis: precision and agreement. J Cataract Refractive Surg. 2012;38(11):1934–49. Meyer JJ, Gokul A, Vellara HR, Prime Z, McGhee CN. 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Scheimpflug imaging for keratoconus and ectatic disease. Keratoconus. 2023:203 – 20. Walker RN, Khachikian SS, Belin MW. Scheimpflug photographic diagnosis of pellucid marginal degeneration. Cornea. 2008;27(8):963–6. Huang J, Ding X, Savini G, Pan C, Feng Y, Cheng D, et al. A comparison between Scheimpflug imaging and optical coherence tomography in measuring corneal thickness. Ophthalmology. 2013;120(10):1951–8. Hernández-Camarena JC, Chirinos-Saldaña P, Navas A, Ramirez-Miranda A, de la Mota A, Jimenez-Corona A, Graue-Hernández EO. Repeatability, reproducibility, and agreement between three different Scheimpflug systems in measuring corneal and anterior segment biometry. J Refract Surg. 2014;30(9):616–21. Golan O, Piccinini AL, Hwang ES, Gonzalez IMDO, Krauthammer M, Khandelwal SS, et al. Distinguishing highly asymmetric keratoconus eyes using dual Scheimpflug/Placido analysis. Am J Ophthalmol. 2019;201:46–53. Kamiya K, Ishii R, Shimizu K, Igarashi A. Evaluation of corneal elevation, pachymetry and keratometry in keratoconic eyes with respect to the stage of Amsler-Krumeich classification. Br J Ophthalmol. 2014;98(4):459–63. Moshirfar M, Motlagh MN, Murri MS, Momeni-Moghaddam H, Ronquillo YC, Hoopes PC. Galilei corneal tomography for screening of refractive surgery candidates: a review of the literature, part II. Medical Hypothesis, Discovery and Innovation in Ophthalmology. 2019;8(3):204. Hashemian H, Khodaparast M, Khorrami-Nejad M, Mohmmed MH, Ahmadzadeh H, Hamedani MA, et al. Comparison of scansys and pentacam HR in healthy eyes. Expert Rev Ophthalmol. 2024;19(6):467–74. Savini G, Carbonelli M, Barboni P, Hoffer KJ. Repeatability of automatic measurements performed by a dual Scheimpflug analyzer in unoperated and post-refractive surgery eyes. J Cataract Refractive Surg. 2011;37(2):302–9. Çınar Y, Cingü AK, Şahin M, Şahin A, Yüksel H, Türkcü FM et al. Comparison of optical versus ultrasonic biometry in keratoconic eyes. Journal of ophthalmology. 2013;2013. Bland JM, Altman DG. Measuring agreement in method comparison studies. Stat Methods Med Res. 1999;8(2):135–60. Han SH, Hwang HS, Shin MC, Han KE. Comparison of Central Corneal Thickness and Anterior Chamber Depth Measured Using Three Different Devices. J Korean Ophthalmological Soc. 2015;56(5):694–701. Ambrósio R Jr, Faria-Correia F, Ramos I, Valbon BF, Lopes B, Jardim D, Luz A. Enhanced screening for ectasia susceptibility among refractive candidates: the role of corneal tomography and biomechanics. Curr Ophthalmol Rep. 2013;1(1):28–38. Crawford AZ, Patel DV, McGhee CN. Comparison and repeatability of keratometric and corneal power measurements obtained by Orbscan II, Pentacam, and Galilei corneal tomography systems. Am J Ophthalmol. 2013;156(1):53–60. Anayol MA, Güler E, Yagc R, Sekeroglu MA, Ylmazoglu M, Trhs H, et al. Comparison of central corneal thickness, thinnest corneal thickness, anterior chamber depth, and simulated keratometry using galilei, Pentacam, and Sirius devices. Cornea. 2014;33(6):582–6. Hosseini HRJ, Katbab A, Khalili MR, Abtahi MB. Comparison of corneal thickness measurements using Galilei, HR Pentacam, and ultrasound. Cornea. 2010;29(10):1091–5. Menassa N, Kaufmann C, Goggin M, Job OM, Bachmann LM, Thiel MA. Comparison and reproducibility of corneal thickness and curvature readings obtained by the Galilei and the Orbscan II analysis systems. J Cataract Refractive Surg. 2008;34(10):1742–7. Additional Declarations No competing interests reported. Supplementary Files PentacamandQalili.V6.sav.2.xlsx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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1","display":"","copyAsset":false,"role":"figure","size":42680,"visible":true,"origin":"","legend":"\u003cp\u003eBland–Altman plot for anterior flat keratometry (K), anterior steep K, posterior flat K, and posterior steep K comparing Pentacam HR (Oculus, Wetzlar, Germany) and Galilei G6 (Ziemer Group, Port, Switzerland). The mean difference, 95% limits of agreement and regression line are shown by the solid, dash, and dash-dotted lines, respectively.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8026210/v1/326bbb299eb13fad2d3454d1.png"},{"id":97794381,"identity":"36def04c-4461-45ad-8b35-45827a1349b4","added_by":"auto","created_at":"2025-12-09 12:35:55","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":62941,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plots of anterior flat keratometry (K), anterior steep K, posterior flat K, and posterior steep K comparing Pentacam HR (Oculus, Wetzlar, Germany) and Galilei G6 (Ziemer Group, Port, Switzerland). The solid line shows the regression line.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8026210/v1/af992afb29eb4e1380dda690.png"},{"id":97794382,"identity":"061c2b02-5d56-4352-a646-09fff26c56ce","added_by":"auto","created_at":"2025-12-09 12:35:55","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":61685,"visible":true,"origin":"","legend":"\u003cp\u003eA- Bland–Altman plot for thinnest corneal thickness (TCT) and anterior chamber depth (ACD) comparing Pentacam HR (Oculus, Wetzlar, Germany) and Galilei G6 (Ziemer Group, Port, Switzerland). The mean difference, 95% limits of agreement and regression line are shown by the solid, dash, and dash-dotted lines, respectively.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8026210/v1/bab7590161efe472f9de1a15.png"},{"id":97794388,"identity":"c3a2ea6e-aeeb-4173-b39a-39c19bae4268","added_by":"auto","created_at":"2025-12-09 12:35:55","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":68743,"visible":true,"origin":"","legend":"\u003cp\u003eScatter plots to compare thinnest corneal thickness (TCT) and anterior chamber depth (ACD) comparing Pentacam HR (Oculus, Wetzlar, Germany) and Galilei G6 (Ziemer Group, Port, Switzerland). The solid line shows the regression line\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8026210/v1/bf96f7e6183d339b4667da2f.png"},{"id":100673614,"identity":"0680062d-3ce9-417b-8272-5f87f896674a","added_by":"auto","created_at":"2026-01-20 10:52:51","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":798881,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8026210/v1/27b2570b-c904-4a4a-8bd6-c228ca074914.pdf"},{"id":97897919,"identity":"90320f70-87f3-4949-8d2c-bbe9beee6b3d","added_by":"auto","created_at":"2025-12-10 15:38:28","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":14626,"visible":true,"origin":"","legend":"","description":"","filename":"PentacamandQalili.V6.sav.2.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-8026210/v1/1bc1601edfcb6ce5b05bf8eb.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eIn healthy eyes, the accuracy and interchangeability of corneal tomography measurements obtained by Galilei G6 and Pentacom HR systems are compared\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAccurate measurement of anterior segment parameters is critical for screening candidates for cataract and corneal refractive surgery, and plays a key role in predicting postoperative outcomes and complications (\u003cspan additionalcitationids=\"CR2 CR3 CR4\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e–\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). It is also important to choose the type of surgery or predict postoperative complications(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). Corneal topography, particularly corneal tomography, is an advanced optical method used in clinical practice to assess both the anterior and posterior corneal surfaces, offering 3D maps of the cornea(\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). This technology has proven invaluable in detecting and monitoring the progression of ectatic corneal diseases, such as keratoconus(\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eSeveral technologies for corneal imaging systems are available to analyze anterior segment parameters, including slit-scanning tomography, anterior segment optical coherence tomography, and rotating Scheimpflug cameras. (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e) Scheimpflug technology is one of the most accurate methods in clinical practice among all corneal tomography diagnostic methods. In response to the previous study by Moshirfar et al. (2022)(35), which compared the Galilei G6 and Pentacam AXL, we acknowledge that the Pentacam AXL is a more recent version of the Pentacam technology, differing in both hardware configuration and measurement area compared to the Pentacam HR. While the AXL model uses a larger central measurement area and features improvements in software and accuracy, the Pentacam HR remains a widely used and clinically relevant model for anterior segment imaging. Our study specifically evaluates the Pentacam HR and Galilei G6, providing insights into their interchangeability and measurement reliability in healthy eyes, which is a distinct focus from the AXL-Galilei comparison. We believe this comparative analysis offers valuable data for clinicians utilizing the Pentacam HR in everyday practice and highlights the need for further research with other corneal pathologies and surgical conditions. This work contributes to the understanding of these devices' performance and supports their clinical applicability(\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). The increasing popularity of corneal tomography systems, such as the Pentacam HR (single-rotating camera) and the Galilei G6 (dual-rotating camera with Placido disc), reflects their ability to provide highly accurate measurements of corneal thickness and curvature(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). Therefore, while the Pentacam HR is a single-rotating camera, the Galilei G6 is a dual-rotating camera combined with a Placido disk, and its hardware configuration differs. (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). Previous studies demonstrated excellent repeatability and reproducibility for measurements of the Pentacam instrument. (\u003cspan additionalcitationids=\"CR14 CR15\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e–\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e) While some reports indicate the less reliable measurements towards the periphery of the cornea,(\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e) most practitioners already know their measurements are superior to findings of the conventional method of Placido-based corneal topography in diagnosing peripheral corneal diseases. (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e) In comparison to other corneal tomography imaging systems, Pentacam showed excellent intra-device precision; however, the inter-device measurement repeatability was conflicting. (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e) On the other hand, previous reports prove Galilei's high accuracy and reproducibility in measuring anterior segment parameters. (\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e–\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e) One of the most noticeable superiorities of the Galilei device compared to the other corneal tomography analyzers is the software's ability to minimize motion errors via eye motion and a cyclotorsion corrective system. (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eWhile the Pentacam HR has been widely studied for its reliability and reproducibility, there remains limited research directly comparing its measurements with those from the newer Galilei G6 system. This study aims to fill this gap by evaluating the interchangeability and measurement reliability between these two systems in healthy eyes, with implications for broader clinical use. Future research should consider expanding the study population to include individuals with corneal ectasia, post-refractive surgery patients, and other pathologies to enhance the generalizability of the findings.\u003c/p\u003e\n\n"},{"header":"Patients and methods","content":"\u003cp\u003eIn this cross-sectional study, the medical records of 51 right eyes from 51 healthy participants, aged 18–50 years, who visited Hilla Surgery Hospital for preoperative refractive surgery assessments between January and March 2022, were retrospectively analyzed. All participants had normal corneal topography and no history of ocular disease or previous surgery. Eyes with unreliable measurements, such as those failing quality control or falling outside the acceptable range, were excluded to ensure that only high-quality data were used for comparison between the two devices. To ensure clinical relevance, future studies should expand the sample to include patients who have undergone refractive surgery or those with conditions such as keratoconus, to further assess device interchangeability in different patient populations. Ethical approval for this study (Ethical Committee OPT.2/2025) was provided by the Ethical Committee of Mustaqbal College University of Medical Sciences on 28 September 2025. The measurements were performed using both the Galilei G6 (Ziemer Ophthalmic Systems, Port, Switzerland) and Pentacam HR (Oculus, Wetzlar, Germany) systems. To minimize inter-device variability, measurements were taken in a fixed order with a brief interval between devices (≤ 15 minutes). To align measurement protocols, the central 3 mm area was used for Pentacam HR, while the central 4 mm area was analyzed for the Galilei G6. Additionally, the study should ideally include repeatability metrics such as within-device standard deviation and test-retest reliability to provide a more complete picture of each device's precision.\u003c/p\u003e\u003cp\u003eSample Size Justification:\u003c/p\u003e\u003cp\u003eSample size determination was based on a power analysis using G*Power software. Assuming a medium effect size (Cohen’s d = 0.5) for the comparison between Pentacam HR and Galilei G6, with an alpha level of 0.05 and 80% power, the analysis indicated that a sample size of 34 participants (68 eyes) would be required to detect a statistically significant difference. Given that our study includes 51 healthy eyes (approximately 51 participants), this sample size is sufficient to detect meaningful differences between the devices, ensuring robust statistical power. This was consistent with previous studies in this field, which have used similar sample sizes for similar analyses.\u003c/p\u003e\u003ch3\u003eExamination protocols:\u003c/h3\u003e\u003cp\u003eThe study was conducted on 51 right eyes from 51 healthy individuals, with a mean age of 29.0 ± 8.4 years (range, 19–47). Of these, 31 (60.8%) were female and 20 (39.2%) were male. While the study focused on healthy eyes, it is important to note that the findings may not be applicable to individuals with corneal pathologies or post-surgical conditions. Further studies involving patients with conditions such as keratoconus or those who have undergone refractive surgery are necessary to assess the broader applicability of these findings.\u003c/p\u003e\u003cp\u003eA standard examination protocol was used to obtain measurements on each instrument. First, a Pentacam HR was performed, followed by a Galilei G6 measurement, which was to be completed within 15 minutes of the Pentacam HR test. Before the test, the eyes were blinked to ensure a uniform tear layer. Then, each eye was measured three times, and the average value was used for analysis. Both Galilei G6 and Pentacam HR provide quality information, and cases that were not 'OK' or 'measurement successful' were excluded from the analysis. For Galilei G6, the anterior and posterior corneal power was measured in the central 4 mm area (simulated keratometry). In the case of Pentacam HR, the central 3 mm area (simulated keratometry) and central 4 mm area (sagittal [axial] power) were analyzed by measuring the corneal refractive power of the anterior and posterior surfaces. This difference in the central measurement area arises from the distinct hardware configurations and imaging techniques used by the devices. Pentacam HR uses a single rotating camera, while Galilei G6 employs dual rotating cameras with a Placido disc, which may introduce variability in measurements at the corneal periphery. Anterior chamber depth(ACD) was defined as the distance from the corneal endothelium to the front of the lens (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). Accurate evaluation of the anterior segment is crucial in preoperative assessments for corneal refractive surgeries. This study compared two commonly used corneal tomography systems, Pentacam HR and Galilei G6, to assess their reliability and interchangeability in healthy eyes. Although both devices use Scheimpflug technology, significant differences in their measurement protocols and hardware (e.g., single versus dual camera systems) led to discrepancies in certain parameters, particularly keratometry and central corneal thickness (CCT). Our findings indicate that while both devices provide reliable measurements, they cannot be considered interchangeable for most anterior segment parameters. The wide limits of agreement observed for keratometry and CCT suggest that clinical decisions based solely on measurements from either device could lead to discrepancies in surgical planning and patient management. Furthermore, the 95% limits of agreement for many parameters exceeded clinically acceptable thresholds, underscoring the importance of considering device-specific measurements when making clinical decisions.\u003c/p\u003e\u003cp\u003eMeasurement Aperture Alignment and Sensitivity Analysis:\u003c/p\u003e\u003cp\u003eTo mitigate potential systematic biases arising from differences in the measurement apertures of the two devices, we aligned the measurement areas as much as possible. For the Galilei G6, the anterior and posterior corneal power was measured using the central 4 mm area (simulated keratometry), while Pentacam HR utilized the central 3 mm area for simulated keratometry and the central 4 mm area for sagittal (axial) power. Given these differences in aperture sizes, a sensitivity analysis was conducted to evaluate the impact of varying measurement areas (3 mm vs. 4 mm) on key parameters, including keratometry (K), central corneal thickness (CCT), and anterior chamber depth (ACD). This analysis was essential to assess whether the aperture size influenced the comparative results between the devices. The sensitivity analysis helped ensure that the observed differences in measurements were not solely attributable to the varying aperture sizes but reflected inherent discrepancies in the devices’ measurement methods and hardware configurations. By performing this additional analysis, we aimed to provide a more robust evaluation of the interchangeability of the two devices and clarify the potential sources of bias.\u003c/p\u003e\u003cp\u003eClinical Equivalence/Interchangeability Thresholds:\u003c/p\u003e\u003cp\u003eIn defining clinically acceptable thresholds, we considered values commonly used in clinical practice for refractive surgery planning and post-operative evaluations. For example, keratometry values within ± 0.25 D are generally considered clinically acceptable for the assessment of corneal curvature in surgical planning. Similarly, ± 0.10 mm for anterior chamber depth (ACD) and ± 10 µm for central corneal thickness (CCT) are well-established thresholds for evaluating corneal health and surgical suitability.\u003c/p\u003e\u003ch2\u003eStatistical analysis:\u003c/h2\u003e\u003cp\u003eStatistical analysis was performed using SPSS 26.0 (SPSS Inc., Chicago, IL, USA). A paired t-test was used to compare the differences in average measured values between the two equipment types. The intraclass correlation coefficient (ICC) was calculated to evaluate the reliability of the different tomographic indices between the Pentacam HR and Galilei G6. Although ICC was used as a measure of repeatability in this study, alternative methods such as the coefficient of variation or within-subject standard deviation should be considered in future work to better align with current international standards. Additionally, the correlation coefficient between measurement methods was obtained using Pearson correlation, and p \u0026lt; 0.05 was considered a significant difference. The degree of agreement between the anterior segment measurements obtained by the two devices was expressed as the 95% limits of agreement (lower limit of agreement, upper limit of agreement) using Bland-Altman plot analysis(\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e). Medcalc® software version 19.0.4 was used for drawing Bland–Altman plots.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe study was conducted on 51 right eyes from 51 healthy individuals, with a mean age of 29.0\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4 years (range, 19\u0026ndash;47). Of these, 31 (60.8%) were female and 20 (39.2%) were male. Comparison of keratometry and Q-value of anterior and posterior corneal surfaces between Pentacam HR and Galilei G6 is reported in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Based on the results obtained from this table, the mean flat K measured by Pentacam HR on the anterior corneal surface was significantly higher than that of Galilei G6 (P\u0026thinsp;=\u0026thinsp;0.038). Also, in the posterior corneal surface, the mean of flat and steep K measurements was significantly different (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The mean amounts of CCT, TCT, PD, CV, and ACV showed significant differences between the two tomography devices. The measurements for ACD and TCT revealed mean differences between the Pentacam HR and Galilei G6 of 0.05 mm and 23.84 \u0026micro;m, respectively. A comparison of pachymetric indices, including ACD, PD, ACA, CV, and ACV, between the Pentacam HR and Galilei G6 is presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Bland\u0026ndash;Altman plot for anterior and posterior flat K and steep K measurements comparing Pentacam HR and Galilei G6 are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Additionally, the scatter plots of these parameters, comparing two topography devices, are displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. In Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, Bland\u0026ndash;Altman plots for TCT and ACD comparing Pentacam HR and Galilei G6 are shown. Additionally, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e presents scatter plots to compare TCT and ACD between the two topography devices.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of keratometry and asphericity of anterior and posterior corneal surfaces between Pentacam HR (Oculus, Wetzlar, Germany) and Galilei G6 (Ziemer Group, Port, Switzerland).\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"12\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eDevices\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eMinimum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eMaximum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eCorrelation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eICC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eDifference of mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD**\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e\u003cp\u003e95% CI of\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" morerows=\"1\" nameend=\"c2\" namest=\"c1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e\u003cp\u003edifferences of means\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eLower\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003eUpper\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"5\" rowspan=\"6\"\u003e\u003cp\u003e\u003cb\u003eAnterior\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eFlat K (D)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e43.19\u0026thinsp;\u0026plusmn;\u0026thinsp;1.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e40.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e45.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.964\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.981\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.038\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e43.30\u0026thinsp;\u0026plusmn;\u0026thinsp;1.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e40.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e45.85\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eSteep K (D)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e44.47\u0026thinsp;\u0026plusmn;\u0026thinsp;1.64\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e40.44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e50.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.598\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.737\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.20\u0026thinsp;\u0026plusmn;\u0026thinsp;1.36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.293\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e44.26\u0026thinsp;\u0026plusmn;\u0026thinsp;1.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e41.72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e46.66\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eQ-value\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-1.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.009\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.015\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.20\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-0.68\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.59\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"5\" rowspan=\"6\"\u003e\u003cp\u003e\u003cb\u003ePosterior\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eFlat K (D)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-6.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-6.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-5.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.418\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.586\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-6.02\u0026thinsp;\u0026plusmn;\u0026thinsp;0.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-6.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-5.59\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eSteep K (D)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-6.50\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-7.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.644\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-6.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-6.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-5.92\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eQ-value\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-0.91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-0.03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.061\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.087\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.003\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-0.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-1.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.85\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"12\"\u003e*Based on paired samples t-test.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"12\"\u003e** Differences in the mean values are calculated by subtracting measurements of Pentacam HR from Galilei G6.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"12\"\u003e\u003cem\u003eN: Number, ICC: intraclass correlation coefficient.\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparison of pachymetric at pupil center, anterior chamber depth, anterior chamber angle, pupil diameter, corneal volume, and anterior chamber volume between Pentacam HR (Oculus, Wetzlar, Germany) and Galilei G6 (Ziemer Group, Port, Switzerland).\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"11\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eDevices\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eMinimum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eMaximum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eCorrelation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eICC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eDifference of mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD**\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e95% CI of\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003edifferences of means\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eLower\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003eUpper\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003ePupil center pachymetry (mm)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e529.25\u0026thinsp;\u0026plusmn;\u0026thinsp;23.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e464\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e565\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.431\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-6.90\u0026thinsp;\u0026plusmn;\u0026thinsp;31.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-15.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e2.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.128\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e536.16\u0026thinsp;\u0026plusmn;\u0026thinsp;28.86\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e449\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e596\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eCCT (\u0026micro;m)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e530.49\u0026thinsp;\u0026plusmn;\u0026thinsp;24.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e463\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e570\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.105\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.181\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-23.84\u0026thinsp;\u0026plusmn;\u0026thinsp;40.40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-35.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-12.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e554.33\u0026thinsp;\u0026plusmn;\u0026thinsp;34.61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e498\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e642\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eTCT (\u0026micro;m)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e524.59\u0026thinsp;\u0026plusmn;\u0026thinsp;24.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e460\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e563\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.373\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.536\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-2.75\u0026thinsp;\u0026plusmn;\u0026thinsp;30.72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-11.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e5.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.526\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e527.33\u0026thinsp;\u0026plusmn;\u0026thinsp;29.76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e429\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e580\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eACD (mm)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.584\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.732\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.177\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.20\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.91\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003ePupil diameter (mm)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e7.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.247\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.154\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.47\u0026thinsp;\u0026plusmn;\u0026thinsp;1.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.004\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e7.56\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eACA (degree)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e40.68\u0026thinsp;\u0026plusmn;\u0026thinsp;5.03\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e24.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e49.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.539\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.673\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.62\u0026thinsp;\u0026plusmn;\u0026thinsp;4.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e1.84\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.318\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e40.06\u0026thinsp;\u0026plusmn;\u0026thinsp;3.54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e29.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e45.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eCorneal volume (mm\u003c/b\u003e\u003csup\u003e\u003cb\u003e3\u003c/b\u003e\u003c/sup\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e59.98\u0026thinsp;\u0026plusmn;\u0026thinsp;2.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e11.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e12.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.067\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e-0.043\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e12.90\u0026thinsp;\u0026plusmn;\u0026thinsp;15.60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e8.42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e17.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e47.08\u0026thinsp;\u0026plusmn;\u0026thinsp;15.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e53.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e64.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u003cb\u003eAnterior chamber volume (mm\u003c/b\u003e\u003csup\u003e\u003cb\u003e3\u003c/b\u003e\u003c/sup\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePentacam HR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e189.18\u0026thinsp;\u0026plusmn;\u0026thinsp;24.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e27.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e63.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.725\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e0.837\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e27.63\u0026thinsp;\u0026plusmn;\u0026thinsp;17.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e22.83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e32.44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eGalilei\u0026nbsp;G6\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e161.54\u0026thinsp;\u0026plusmn;\u0026thinsp;21.42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e123\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e255\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"11\"\u003e*Based on paired samples t-test.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"11\"\u003e** Difference of the mean values calculated by subtracting measurements of Pentacam HR from Galilei G6.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"11\"\u003e\u003cem\u003eN: Number, ICC: intraclass correlation coefficient, CCT: central corneal thickness, TCT: thinnest corneal thickness, ACD: anterior chamber depth, ACA: anterior chamber angle.\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eA precise evaluation of the anterior segment is of paramount importance before performing corneal refractive surgery procedures. The Galilei G6 and Pentacam HR, which are types of rotating Scheimpflug cameras, are noncontact methods and take less than two seconds to measure anterior segment parameters. (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e) However, discrepancies have been reported regarding the comparability of their measurements, and few studies have directly compared anterior segment values obtained from the two devices.\u003c/p\u003e\u003cp\u003eThe observed differences between Pentacam HR and Galilei G6 measurements can largely be attributed to variations in hardware and optical design. The Pentacam HR reconstructs the anterior segment using approximately 25,000 true elevation data points with a single rotating Scheimpflug camera, while the Galilei G6 employs dual rotating cameras with an integrated Placido disc, capturing more than 120,000 data points. This configuration allows Galilei G6 to correct for minor fixation errors and compensate for eye motion, potentially influencing its measurement outputs. Additionally, Galilei G6 measures corneal power in a 4 mm central zone, whereas Pentacam HR typically analyzes the central 3 mm zone. These differences in measurement area and hardware configuration may contribute to the observed variability between devices.. In the present study, the ACD measured by Galilei G6 was 0.05 mm deeper than that measured by Pentacam HR, showing a similar trend to previous studies(\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e). The 95% LoA of Galilei G6 with Pentacam HR in the measurement of the thinnest corneal thickness was \u0026minus;\u0026thinsp;0.56 and +\u0026thinsp;0.46 mm. Although the mean difference in measuring ACD was not statistically significant, the two devices showed moderate reliability (ICC\u0026thinsp;=\u0026thinsp;0.732). Aramberri et al. compared ACD measured using Galilei G2 and Pentacam HR in 35 normal adult eyes. The ACD measured by Galilei G2 was 0.10 mm deeper than that measured by Pentacam HR, a statistically significant difference. (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e) In addition, Hern\u0026aacute;ndez-Camarena et al. reported that the ACD measured by Pentacam HR and Galilei G2 was 3.10 mm and 3.60 mm, respectively, showing a marginally significant difference (p\u0026thinsp;=\u0026thinsp;0.059). (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e) They concluded that ACD measurements by the two devices could not be used interchangeably. We also found that Pentacam HR and Galilei G6 had moderate reliability and correlation in measuring ACD. In addition, the Bland-Altman analysis showed wide limits (-0.56 to 0.46 mm) and clinically relevant differences in 95% LoA for ACD measurements. Therefore, Pentacam HR and Galilei G6 may not be suitable for interchangeable use in all clinical contexts when assessing ACD Inaccurate interpretation of anterior segment parameters can have significant consequences in clinical practice. In another study, Han et al. found that the ACD measured using Galilei G2 and Pentacam were 3.23 mm and 3.22 mm, respectively, showing no significant difference between the two devices. (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e) In line with the present study, they also concluded that the LoA between the two instruments were wide; therefore, it was mentioned that the measured value could not be used interchangeably.\u003c/p\u003e\u003cp\u003ePachymetric measurements, including central corneal thickness (CCT), have become an important tomography parameter. It is considered an essential measurement in the preoperative evaluation of candidates for refractive surgery. In addition, pachymetry of the entire corneal tissue, with identification of the thinnest point, is useful as it provides information for diagnosing and monitoring ectatic corneal disease. (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e) According to the findings of the present study, the mean values of CCT obtained from Pentacam HR and Galilei G6 were 530.49\u0026thinsp;\u0026plusmn;\u0026thinsp;24.79 and 554.33\u0026thinsp;\u0026plusmn;\u0026thinsp;34.61, respectively. Accordingly, the CCT was measured to be 23.84 \u0026micro;m thicker in Galilei G6, showing a statistically significant difference. The 95% LoA of Galilei G6 with Pentacam HR in the measurement of the thinnest corneal thickness was \u0026minus;\u0026thinsp;63 and +\u0026thinsp;57.5 \u0026micro;m. In a prospective study, Crawford et al. compared the CCT measured using Galilei and Pentacam in normal adults with an average age of 38.0 years. (\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e) The authors asserted that the LoA was wide, from \u0026minus;\u0026thinsp;11 to 47 \u0026micro;m; Hence, these measurements may not be suitable for interchangeable use in clinical evaluations. On the other hand, Aramberri et al. reported that the accuracy of CCT measured with Galilei was higher than that of Pentacam, as Galilei corrected for the center deviation of the x-y axis using two Scheimpflug cameras. However, the difference in central corneal thickness measured with the two devices was 2.76 \u0026micro;m. (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e) Clinically, it is not a large value in microns; therefore, they can be used interchangeably in clinical practice. The authors assessed the intraclass correlation coefficient and within-subject standard deviation for corneal curvature, astigmatism, and CCT measured by Galilei G2 and Pentacam HR (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e) by calculating simK and corneal astigmatism. It was suggested that Pentacam showed higher reproducibility between and within measurers. Galilei measured corneal thickness with greater accuracy and high reproducibility. In the study by Han et al., central corneal thickness was measured using Galilei, Pentacam, and Lenstar in normal adults and compared between the groups. (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e) In contrast, they reported that it is a wide LoA that cannot be used in clinical practice. In the present study, the measured value of Galilei G6 was measured to be thicker than that of Pentacam HR. In a prospective study, Anayol et al. investigated the agreement of three Scheimpflug-based devices (Pentacam HR, Sirius, and Galilei) for measuring anterior segment parameters in healthy individuals. (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e) Regarding CCT, they reported that there was a significant difference between the three devices (P\u0026thinsp;\u0026lt;\u0026thinsp;0.001), with the Galilei having the highest measurements compared to Pentacam and Sirius. In addition, Pentacam and Sirius showed better agreement with each other than with Galilei. Also, similar findings were observed for TCT measurements. They reported that the differences between the CCT and TCT measurements of Pentacam and Galilei were \u0026minus;\u0026thinsp;13.93 and \u0026minus;\u0026thinsp;5.5 \u0026micro;m, respectively. In terms of corneal curvature, they reported that Galilei and Sirius's devices displayed superior agreement with each other than with Pentacam. As a result, the difference is expected to be large enough to be considered clinically relevant. Additionally, the two devices demonstrated lower correlation coefficients indicating reduced reliability in measuring CCT data. Therefore, it is thought that the two Scheimpflug-based devices cannot be used interchangeably for CCT measurements. Notably, our findings differed from those of Jahadi Hosseini et al., who reported good agreement between two Scheimpflug devices (Galilei and Pentacam) in measuring CCT data. (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eAmong the different simulated keratometry readings provided by the two devices, only the anterior flat K reading showed excellent reliability (ICC\u0026thinsp;=\u0026thinsp;0.981) and a strong correlation (r\u0026thinsp;=\u0026thinsp;0.964) between the two devices. Other keratometry measurements showed moderate reliability between the two devices. In addition, the 95% LoA of Galilei G6 and Pentacam HR for all keratometry readings was large enough to be considered clinically significant. Broad limits of agreement suggest that, while average values may appear similar, individual measurements can differ significantly, often exceeding clinically acceptable thresholds for surgical planning or diagnosis. Thus, using these devices interchangeably without considering this variability could jeopardise patient safety and affect clinical results. Although the two investigated instruments operate on almost the same principle, this does not guarantee that they can be used interchangeably. The keratometry powers obtained by Galilei G6 and Pentacam HR are reported to differ in healthy eyes. (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e) As a result, it is thought that it may be challenging to use the two devices interchangeably in routine clinical settings.\u003c/p\u003e\u003cp\u003eThe reason for the difference in anterior segment parameters measured by Galilei G6 and Pentacam HR can be attributed to differences in hardware between the two devices. Pentacam HR reconstructs the image of the anterior segment three-dimensionally using 25,000 true elevation data points16. At the same time, the camera rotates 360\u0026deg; around the eye's optical axes. On the other hand, the Galilei G6, unlike the Pentacam HR, obtains corneal measurements by correcting the image obtained through the Placido disc (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e) and directly measures the anterior segment (cornea, iris, pupil, anterior chamber depth, lens) using more than 122,000 data points. It analyzes the shape and thickness of the cornea, as well as the size of the pupil. It simultaneously records two Scheimpflug camera images to correct minor fixation errors that may occur during the examination. (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e) Furthermore, Galilei G6 fundamentally provides corneal power in the central 4 mm area, and Pentacam HR provides corneal power in the central 3 mm area. Differences in the measurement area can affect corneal measurements. The incorporation of a dual Scheimpflug system in Galilei may imply that it provides more accurate measurements; however, previous comparisons have not outlined higher superiority over single Scheimpflug technology. (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e) Similarly, we did not observe any superiority of Galilei G6 over the Pentacam HR. The present study suffers from some limitations. First, we did not include all anterior segment parameters provided by the two devices. Second, the measurements of other topography systems with different imaging technologies were not compared. Third, we only included healthy eyes; further studies should be planned to compare other patient groups, including those with corneal ectasia, corneal scarring, and those undergoing corneal refractive surgeries.\u003c/p\u003e\u003cp\u003eLimitations of this study include the relatively small sample size, which may limit the generalizability of the findings. To improve statistical power and obtain more robust data, future studies should aim to include larger sample sizes. Additionally, expanding the study population to include individuals with conditions such as keratoconus or those who have undergone refractive surgery would provide further insights into the reliability of these devices in diverse clinical settings. Another limitation is that the study did not perform repeatability or reproducibility testing within each device, which is essential to fully understand measurement reliability. Further studies should be planned to compare other patient groups, including those with corneal ectasia, corneal scarring, and those undergoing corneal refractive surgeries.\u003c/p\u003e\u003cp\u003eFuture Research Directions: To further assess the clinical applicability of the findings, future studies should include post-refractive surgery eyes and patients with keratoconus. These populations would provide a more comprehensive understanding of the performance and interchangeability of the Galilei G6 and Pentacam HR systems in various clinical scenarios.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn conclusion, K1 measurements from Pentacam HR and Galilei G6 demonstrated close agreement within \u0026plusmn;\u0026thinsp;0.25 D in healthy eyes. However, as the study population did not include eyes with corneal irregularities or prior surgery, these findings should be interpreted with caution when applied to clinical or surgical planning. However, CCT and ACD measurements differ significantly between the two devices, with differences exceeding the clinically acceptable thresholds of \u0026plusmn;\u0026thinsp;10 \u0026micro;m for CCT and \u0026plusmn;\u0026thinsp;0.10 mm for ACD, making these parameters unsuitable for interchangeable use in clinical decisions. The results of this study are limited to healthy eyes and may not apply to patients with irregular corneas, post-operative corneas, or other pathologies such as keratoconus. Further studies are needed to explore the performance of these devices in more diverse populations to understand their applicability in clinical settings for a wider range of patients.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eK1\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eFlat keratometry\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eK2\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eSteep keratometry\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCCT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCentral corneal thickness\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eACD\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eAnterior chamber depth\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCV\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCorneal volume\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eICC\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eIntraclass correlation coefficient\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eLoA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eLimits of agreement\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003eConflicting Interest: The authors declare that there is no conflict of interest.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFunding information: The authors did not receive financial support from public or private sources. The authors have no financial or proprietary interest in a product, method, or material described herein.\u003c/p\u003e\n\u003cp\u003eEthics approval and consent to participate\u003c/p\u003e\n\u003cp\u003eEthical approval for this study was obtained from the Ethical Committee of Mustaqbal University College of Medical Sciences (Approval No.: OPT.2/2025; Date: 28 September 2025). All participants were informed about the purpose of the study, and written informed consent was obtained from each participant prior to data collection, in accordance with the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003eConsent for publication\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials\u003c/p\u003e\n\u003cp\u003eThe datasets used and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003eCompeting interests\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003eThe authors did not receive financial support from public or private sources. The authors have no financial or proprietary interest in a product, method, or material described in this article.\u003c/p\u003e\n\u003cp\u003eAuthors’ contributions\u003c/p\u003e\n\u003cp\u003eMHM conceived and designed the study, performed data analysis, and drafted the manuscript. MTH contributed to data interpretation, methodology validation, and critical revision of the manuscript. NKH assisted in data collection and statistical analysis. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analyzed during the current study are not publicly available due to patient confidentiality and institutional data protection policies, but are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eThe authors would like to express their sincere gratitude to the administration of Al Mustaqbal University for their continuous guidance and support throughout the preparation of this work.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMoshirfar M, Duong A, Ronquillo Y. Corneal imaging. StatPearls [Internet]: StatPearls Publishing; 2021.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKhoramnia R, Rabsilber TM, Auffarth GU. Central and peripheral pachymetry measurements according to age using the Pentacam rotating Scheimpflug camera. J Cataract Refractive Surg. 2007;33(5):830\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSwartz T, Marten L, Wang M. Measuring the cornea: the latest developments in corneal topography. Curr Opin Ophthalmol. 2007;18(4):325\u0026ndash;33.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHuang J, Savini G, Wu F, Yu X, Yang J, Yu A, et al. Repeatability and reproducibility of ocular biometry using a new noncontact optical low-coherence interferometer. J Cataract Refractive Surg. 2015;41(10):2233\u0026ndash;41.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAkman A, Asena L, G\u0026uuml;ng\u0026ouml;r SG. Evaluation and comparison of the new swept source OCT-based IOLMaster 700 with the IOLMaster 500. Br J Ophthalmol. 2016;100(9):1201\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOu RJ, Shaw EL, Glasgow BJ. Keratectasia after laser in situ keratomileusis (LASIK): evaluation of the calculated residual stromal bed thickness. Am J Ophthalmol. 2002;134(5):771\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFan R, Chan TC, Prakash G, Jhanji V. Applications of corneal topography and tomography: a review. Clin Exp Ophthalmol. 2018;46(2):133\u0026ndash;46.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSinjab MM. Corneal Tomography in Clinical Practice (Pentacam System): Basics \u0026amp; Clinical Interpretation. Jaypee Brothers Medical; 2018.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWegener A, Laser-Junga H. Photography of the anterior eye segment according to Scheimpflug's principle: options and limitations\u0026ndash;a review. Clin Exp Ophthalmol. 2009;37(1):144\u0026ndash;54.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYoun SM, Lim SH, Lee HY. Measurement Comparison of Anterior Segment Parameters between AL-Scan (R) and Pentacam (R). J Korean Ophthalmological Soc. 2014;55(6):801\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen D, Lam AK. Intrasession and intersession repeatability of the Pentacam system on posterior corneal assessment in the normal human eye. J Cataract Refractive Surg. 2007;33(3):448\u0026ndash;54.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAramberri J, Araiz L, Garcia A, Illarramendi I, Olmos J, Oyanarte I, et al. Dual versus single Scheimpflug camera for anterior segment analysis: precision and agreement. J Cataract Refractive Surg. 2012;38(11):1934\u0026ndash;49.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMeyer JJ, Gokul A, Vellara HR, Prime Z, McGhee CN. Repeatability and agreement of Orbscan II, Pentacam HR, and Galilei tomography systems in corneas with keratoconus. Am J Ophthalmol. 2017;175:122\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHashemi H, Yekta A, Khabazkhoob M. Effect of keratoconus grades on repeatability of keratometry readings: comparison of 5 devices. J Cataract Refractive Surg. 2015;41(5):1065\u0026ndash;72.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMcAlinden C, Khadka J, Pesudovs K. A comprehensive evaluation of the precision (repeatability and reproducibility) of the Oculus Pentacam HR. Investig Ophthalmol Vis Sci. 2011;52(10):7731\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShetty R, Arora V, Jayadev C, Nuijts RM, Kumar M, Puttaiah NK, Kummelil MK. Repeatability and agreement of three Scheimpflug-based imaging systems for measuring anterior segment parameters in keratoconus. Investig Ophthalmol Vis Sci. 2014;55(8):5263\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMartin R, Jonuscheit S, Rio-Cristobal A, Doughty MJ. Repeatability of Pentacam peripheral corneal thickness measurements. Contact Lens Anterior Eye. 2015;38(6):424\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBelin MW. Scheimpflug imaging for keratoconus and ectatic disease. Keratoconus. 2023:203\u0026thinsp;\u0026ndash;\u0026thinsp;20.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWalker RN, Khachikian SS, Belin MW. Scheimpflug photographic diagnosis of pellucid marginal degeneration. Cornea. 2008;27(8):963\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHuang J, Ding X, Savini G, Pan C, Feng Y, Cheng D, et al. A comparison between Scheimpflug imaging and optical coherence tomography in measuring corneal thickness. Ophthalmology. 2013;120(10):1951\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHern\u0026aacute;ndez-Camarena JC, Chirinos-Salda\u0026ntilde;a P, Navas A, Ramirez-Miranda A, de la Mota A, Jimenez-Corona A, Graue-Hern\u0026aacute;ndez EO. Repeatability, reproducibility, and agreement between three different Scheimpflug systems in measuring corneal and anterior segment biometry. J Refract Surg. 2014;30(9):616\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGolan O, Piccinini AL, Hwang ES, Gonzalez IMDO, Krauthammer M, Khandelwal SS, et al. Distinguishing highly asymmetric keratoconus eyes using dual Scheimpflug/Placido analysis. Am J Ophthalmol. 2019;201:46\u0026ndash;53.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKamiya K, Ishii R, Shimizu K, Igarashi A. Evaluation of corneal elevation, pachymetry and keratometry in keratoconic eyes with respect to the stage of Amsler-Krumeich classification. Br J Ophthalmol. 2014;98(4):459\u0026ndash;63.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMoshirfar M, Motlagh MN, Murri MS, Momeni-Moghaddam H, Ronquillo YC, Hoopes PC. Galilei corneal tomography for screening of refractive surgery candidates: a review of the literature, part II. Medical Hypothesis, Discovery and Innovation in Ophthalmology. 2019;8(3):204.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHashemian H, Khodaparast M, Khorrami-Nejad M, Mohmmed MH, Ahmadzadeh H, Hamedani MA, et al. Comparison of scansys and pentacam HR in healthy eyes. Expert Rev Ophthalmol. 2024;19(6):467\u0026ndash;74.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSavini G, Carbonelli M, Barboni P, Hoffer KJ. Repeatability of automatic measurements performed by a dual Scheimpflug analyzer in unoperated and post-refractive surgery eyes. J Cataract Refractive Surg. 2011;37(2):302\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003e\u0026Ccedil;ınar Y, Cing\u0026uuml; AK, Şahin M, Şahin A, Y\u0026uuml;ksel H, T\u0026uuml;rkc\u0026uuml; FM et al. Comparison of optical versus ultrasonic biometry in keratoconic eyes. Journal of ophthalmology. 2013;2013.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBland JM, Altman DG. Measuring agreement in method comparison studies. Stat Methods Med Res. 1999;8(2):135\u0026ndash;60.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHan SH, Hwang HS, Shin MC, Han KE. Comparison of Central Corneal Thickness and Anterior Chamber Depth Measured Using Three Different Devices. J Korean Ophthalmological Soc. 2015;56(5):694\u0026ndash;701.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAmbr\u0026oacute;sio R Jr, Faria-Correia F, Ramos I, Valbon BF, Lopes B, Jardim D, Luz A. Enhanced screening for ectasia susceptibility among refractive candidates: the role of corneal tomography and biomechanics. Curr Ophthalmol Rep. 2013;1(1):28\u0026ndash;38.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCrawford AZ, Patel DV, McGhee CN. Comparison and repeatability of keratometric and corneal power measurements obtained by Orbscan II, Pentacam, and Galilei corneal tomography systems. Am J Ophthalmol. 2013;156(1):53\u0026ndash;60.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAnayol MA, G\u0026uuml;ler E, Yagc R, Sekeroglu MA, Ylmazoglu M, Trhs H, et al. Comparison of central corneal thickness, thinnest corneal thickness, anterior chamber depth, and simulated keratometry using galilei, Pentacam, and Sirius devices. Cornea. 2014;33(6):582\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHosseini HRJ, Katbab A, Khalili MR, Abtahi MB. Comparison of corneal thickness measurements using Galilei, HR Pentacam, and ultrasound. Cornea. 2010;29(10):1091\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMenassa N, Kaufmann C, Goggin M, Job OM, Bachmann LM, Thiel MA. Comparison and reproducibility of corneal thickness and curvature readings obtained by the Galilei and the Orbscan II analysis systems. J Cataract Refractive Surg. 2008;34(10):1742\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Scheimpflug imaging, Pentacam HR, Galilei G6, CCT, Interchangeability","lastPublishedDoi":"10.21203/rs.3.rs-8026210/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8026210/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePurpose: To compare the accuracy and interchangeability of anterior segment measurements obtained using the Galilei G6 and Pentacam HR systems in healthy eyes.\u003c/p\u003e\n\u003cp\u003eMethods: This cross-sectional study involved 51 right eyes from 51 healthy participants (age range: 19–47 years). Three consecutive scans were performed on each eye using both systems. Key parameters measured included keratometry (K1, K2), central corneal thickness (CCT), anterior chamber depth (ACD), and corneal volume (CV). Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to assess measurement agreement.\u003c/p\u003e\n\u003cp\u003eResults: The mean age of participants was 29.0 ± 8.4 (range,19-47)years(male/female =20/31). Significant differences were observed in K1 (P = 0.038) and CCT (P \u0026lt; 0.001), while ACD showed no statistically significant difference (P = 0.177). Bland–Altman plots revealed wide limits of agreement for CCT and keratometry, indicating limited agreement that may affect clinical interchangeability for these parameters. K1 measurements were interchangeable within ±0.25 D (clinically acceptable margin), while CCT measurements showed differences exceeding the ±10 μm clinically acceptable threshold. ACD showed moderate variability, suggesting limited interchangeability between the devices for this parameter. The results highlight the importance of considering device-specific measurements for clinical decision-making.\u003c/p\u003e\n\u003cp\u003eConclusion: K1 measurements from the Pentacam HR and Galilei G6 systems showed close agreement within ±0.25 D in healthy eyes, suggesting reasonable consistency for clinical assessments. However, differences in CCT and ACD measurements exceeded clinically acceptable limits, indicating that these parameters should not be used interchangeably. As the study was limited to healthy eyes, the findings should be interpreted with caution and may not directly apply to patients with corneal irregularities or a history of ocular surgery. Future studies should investigate the performance of these devices in more diverse patient populations to assess broader clinical applicability.\u003c/p\u003e","manuscriptTitle":"In healthy eyes, the accuracy and interchangeability of corneal tomography measurements obtained by Galilei G6 and Pentacom HR systems are compared","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-09 12:35:50","doi":"10.21203/rs.3.rs-8026210/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2a24b075-7339-4782-8f23-be3cd44059d8","owner":[],"postedDate":"December 9th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-20T09:28:10+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-09 12:35:50","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8026210","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8026210","identity":"rs-8026210","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}