Comparison of keratometry measurements using the <scp>P</scp>entacam <scp>HR</scp>, the <scp>O</scp>rbscan IIz, and the <scp>TMS</scp>‐4 topographer

Tajbakhsh, Zahra; Salouti, Ramin; Nowroozzadeh, Mohammad Hossein; Aghazadeh-Amiri, Mohammad; Tabatabaee, Seyedmehdi; Zamani, Mohammad

doi:10.1111/j.1475-1313.2012.00942.x

Cited by 25 publications

(26 citation statements)

References 27 publications

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“…According to the study by Read et al [19], the Pentacam HR also showed higher values for J0 than the Placido topographer. Tajbakhsh et al [3] demonstrated that the Pentacam HR produces the lowest values for the J0 and J45 vectors compared to the two Placido topographers. The study by Read et al [19] showed smaller differences for J0, J45, and Kmean.…”

Section: Discussionmentioning

confidence: 99%

“…Prakash et al [20] compared a Placido-based method with the Pentacam HR, while in our study, the Pentacam HR was compared to a multidot-keratometer. The study by Tajbakhsh et al [3] compared the Pentacam HR with two Placido-based methods, and the Pentacam HR was regarded as interchangeable with the TMS-4 topographer, as the differences in keratometry were not considered clinically relevant. Prakash et al [20] compared the iDesign with a Scheimpflug-Placido combination and suggested that these two devices should not be used interchangeably.…”

Section: Discussionmentioning

confidence: 99%

“…Corneal curvature is required for all intraocular lens (IOL) formulas and thus influences the power of the selected IOL [2]. There are different types of technology for measuring corneal curvature that can be divided into Placido disc-based or slit-scanning-based method and Scheimpflug imaging [3, 4]. When it comes to determining corneal thickness, ultrasound pachymetry is regarded as the gold standard, because of its high degree of reproducibility [5].…”

Section: Introductionmentioning

confidence: 99%

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Repeatability and Agreement of Central Corneal Thickness and Keratometry Measurements between Four Different Devices

Kiraly¹,

Stange

Kunert

et al. 2017

Journal of Ophthalmology

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Background. To estimate repeatability and comparability of central corneal thickness (CCT) and keratometry measurements obtained by four different devices in healthy eyes. Methods. Fifty-five healthy eyes from 55 volunteers were enrolled in this study. CCT (IOLMaster 700, Pentacam HR, and Cirrus HD-OCT) and keratometry readings (IOLMaster 700, Pentacam HR, and iDesign) were measured. For statistical analysis, the corneal spherocylinder was converted into power vectors (J0, J45). Repeatability was assessed by intraclass correlation coefficient (ICC). Agreement of measurements between the devices was evaluated by the Bland-Altman method. Results. The analysis of repeatability of CCT data of IOLMaster 700, Pentacam HR, and Cirrus HD-OCT showed high ICCs (range 0.995 to 0.999). The comparison of CCT measurements revealed statistically significant differences between Pentacam HR versus IOLMaster 700 (p < 0.0001) and Pentacam HR versus Cirrus HD-OCT (p < 0.0001), respectively. There was no difference in CCT measurements between IOLMaster 700 and Cirrus HD-OCT (p = 0.519). The repeatability of keratometry readings (J0 and J45) of IOLMaster 700, Pentacam HR, and iDesign was also high with ICCs ranging from 0.974 to 0.999. The Pentacam HR revealed significantly higher J0 in comparison to IOLMaster 700 (p = 0.009) and iDesign (p = 0.041); however, no significant difference was between IOLMaster 700 and iDesign (p = 0.426). Comparison of J45 showed no significant difference between IOLMaster 700, Pentacam HR, and iDesign. These results were in accordance with Bland-Altman plots. Conclusion. In clinical practice, the devices analyzed should not be used interchangeably due to low agreement regarding CCT as well as keratometry readings.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Repeatability and Agreement of Central Corneal Thickness and Keratometry Measurements between Four Different Devices

Kiraly¹,

Stange

Kunert

et al. 2017

Journal of Ophthalmology

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show abstract

“…Several studies have demonstrated better measurement precision in healthy eyes 10,11 than keratoconic eyes 12–14 , for various clinical parameters and different imaging devices. Previously reported repeatability and reproducibilty data of keratoconic eyes have been inconsistent and vary considerably among different studies and devices.…”

Section: Introductionmentioning

confidence: 99%

Improving precision for detecting change in the shape of the cornea in patients with keratoconus

Brunner

Czanner

Vinciguerra

et al. 2018

Sci Rep

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To investigate a method for precision analysis to discriminate true corneal change from measurement imprecision in keratoconus (KC). Thirty patients with KC and 30 healthy controls were included. Coefficients of repeatability and limits of agreement (LOA) were compared using multiple measurements for inter-observer and inter-device agreement with the Pentacam HR, Orbscan IIz, and Tomey Casia SS-1000. Correlation of repeated measurements was evaluated using a linear mixed effect model (also called random effect model). A formula was derived for the theoretical expected change in precision and compared with measured change. Correlation between measurements from the same eye was small (R = 0.13). The 99.73% LOA (3 SD) of the mean of three measurements, provided better precision than 95% LOA (2 SD) of single cut-off values as expected from statistical theory for uncorrelated measurements for evidence of a significant change in corneal shape in patients with keratoconus. This enabled the determination of cut-off values for the detection of true change in corneal shape. The mean of three repeated measurements will provide better precision when there is minimal correlation. Three (rather than two) standard deviations provides a precise estimate of the LOA within or between observers and can be used as a reliable measure for identifying stage-independent corneal shape changes (progression) in keratoconus.

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“…One useful instrument is the Orbscan (Bausch and Lomb, Rochester, USA) as it allows measurement of many anterior segment parameters. Many studies have investigated the agreement of this device with ultrasound techniques and Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) in measuring important corneal indices like its curvature and thickness 13, 14, 15, 16, 17, 18. Moreover, some studies have shown the role of the indices measured by this device in the diagnosis of keratoconus and its progress 19, 20, 21.…”

Section: Introductionmentioning

confidence: 99%

The distribution of orbscan indices in young population

Hashemi

Khabazkhoob

Yazdani

et al. 2017

Journal of Current Ophthalmology

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PurposeTo determine the distribution of anterior eye biometry indices, such as keratometry pachymetry, anterior chamber depth (ACD), pupil diameter, and corneal diameter, as measured by Orbscan instrument in a young Iranian population.MethodsA cross-sectional study was conducted, and subjects were selected through multistage cluster sampling from the students of Mashhad University of Medical Sciences. Objective and subjective refraction were performed followed by Orbscan imaging.ResultsA total of 1330 subjects were selected, 1121 of which participated in the study. After applying the exclusion criteria, the final analysis was performed on the data of 1051 subjects. The mean age of the participants was 26.1 ± 3.2 years (19–34 years old). The mean ± SD and 95% confidence interval (CI) of maximum keratometry, minimum keratometry, pupil diameter, corneal diameter, ACD, and central corneal thickness was 44.5 ± 1.7 (44.4–44.6), 43.1 ± 1.6 (43.0–43.2), 4.3 ± 0.9 (4.3–4.4), 11.7 ± 0.4 (11.7–11.7), 3.7 ± 0.3 (3.6–3.7), and 550.5 ± 35 (548.4–552.6), respectively. After adjusting for age and the mean spherical equivalent (MSE), maximum keratometry, minimum keratometry, central corneal thickness, and the thinnest pachymetry were statistically significantly higher in female subjects (P < 0.001) whilst the corneal diameter and ACD were higher in male subjects (P < 0.001). The pupil diameter and ACD showed statistically significant changes with age (P < 0.001). The MSE was only correlated with maximum keratometry and ACD (P < 0.001).ConclusionIn this study, the distribution of Orbscan measurements for the anterior segment parameters was reported in a large sample of the young Iranian population. Age, gender, and refractive error may affect the orbscan measurements.

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Comparison of keratometry measurements using the Pentacam HR, the Orbscan IIz, and the TMS‐4 topographer

Cited by 25 publications

References 27 publications

Repeatability and Agreement of Central Corneal Thickness and Keratometry Measurements between Four Different Devices

Repeatability and Agreement of Central Corneal Thickness and Keratometry Measurements between Four Different Devices

Improving precision for detecting change in the shape of the cornea in patients with keratoconus

The distribution of orbscan indices in young population

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