Repeatability of central corneal thickness measurement with the Pentacam HR system

Alonso, Ruiz Simonato; Fontes, Bruno Machado; Ventura, Marcelo Palis; Ambrósio, Renato

doi:10.1590/s0034-72802012000100003

Cited by 5 publications

(4 citation statements)

References 17 publications

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“…Safe values for residual stromal bed thickness following laser in situ keratomileusis (LASIK) [9, 10], and the acceptable percentage of tissue altered [11, 12] has been previously highlighted. All these studies reflect a robust role of corneal thickness as a determinant of corneal properties and an ectasia screening parameter [13–15]. …”

Section: Introductionmentioning

confidence: 99%

Pentacam HR Indices Variation in Normal Corneas with Different Corneal Thickness

Roshdy

Wahba

Elkitkat

et al. 2018

Journal of Ophthalmology

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Purpose To evaluate the effect of variable corneal thickness on Pentacam HR diagnostic indices in normal corneas. Methods Retrospective study was conducted at Al Watany Eye Hospital, Cairo, Egypt. Consecutive 160 eyes of young myopic subjects without KC were evaluated using Pentacam HR (WaveLight Allegro Oculyzer II, Erlangen, Germany). The elevation- and thickness-based indices were recorded. Enrolled corneas were categorized into three groups according to TCT quartiles; group 1 (39 eyes) included corneas with TCT <523 µm, group 2 (81 eyes) with TCT between 523 and 564 µm, while group 3 (40 eyes) enrolled TCT >564 µm. The possible effect of pachymetry on Pentacam HR indices was assessed using partial correlation tests. Results In normal corneas, back elevation from best fit sphere (BE from BFS) and that from best fit toric ellipsoid (BFTE) were the elevation indices that showed statistically significant differences among groups (P=0.013 and 0.019, respectively). Regarding pachymetric indices, maximum pachymetry progression index (PPI max) showed statistical significance (P=0.001). Partial correlations, after excluding age and refractive error effects, showed that TCT was correlated with BE from BFS, BE from BFTE, and PPI max (P=0.001, 0.001,0.002, respectively). Conclusions Some Pentacam HR indices varied with different corneal thickness in normal corneas. This necessitates inclusion of pachymetric subgroups in the normative database. The use of the more robust indices (average pachymetry progression index and front elevations) is recommended in relatively thin or thick corneas.

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Section: Introductionmentioning

confidence: 99%

Pentacam HR Indices Variation in Normal Corneas with Different Corneal Thickness

Roshdy

Wahba

Elkitkat

et al. 2018

Journal of Ophthalmology

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“… 3 Ultrasound pachymetry is the known gold standard for measuring central corneal thickness (CCT) 4 which has limitations such as being invasive, fixation error, and error due to incorrect placement of the probe 5 , 6 ; therefore, other devices based on technologies such as Scheimpflug imaging (Pentacam), slit scanning topography (Orbscan), specular microscopy, dual-beam partial coherence interferometry, optical coherence tomography (OCT), and ultrasound biomicroscopy 7 have found clinical applications. 8 , 9 Repeatability is a requirement for device validity. In the assessment of accuracy, the first parameter which can be relied on is repeatability.…”

Section: Introductionmentioning

confidence: 99%

Corneal thickness measurements with Scheimpflug and slit scanning imaging techniques in keratoconus

Amiri

Hashemi

Ramin

et al. 2017

Journal of Current Ophthalmology

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PurposeTo determine the repeatability of corneal thickness measurements with Scheimpflug (Pentacam) and slit scanning (Orbscan) imaging techniques in different grades of keratoconus.MethodsThis study was conducted as a cross-sectional research. Imaging with Orbscan and Pentacam was performed on patients with different grades of keratoconus. With each device, 3 measurements were taken at 10 min intervals. Repeatability indices in different grades of keratoconus were calculated for each device.ResultsSeventy-four eyes of 42 keratoconus patients were enrolled. Repeatability index (RI) of central corneal thickness (CCT) measurements in keratoconus grade 1, 2, and 3, were 12.8, 9.9, and 24.2 with Pentacam, and 23.6, 26.3, and 59.3 with Orbscan, respectively. For the thinnest point, these figures were 9.6, 8.0, and 35.7 with Pentacam and 19.5, 16.6, and 26.8 with Orbscan, respectively.The 95% limit of agreement (LOA) between Pentacam and Orbscan in measuring CCT and thinnest point in grade 1 were −25.5–47.7 mic and −33.3–32.8 mic, respectively. These results for grade 2 were −9.8–50.6 mic and −26.2–43.7 mic, respectively. In grade 3, 95% LoA were −20–64.6 mic and −31.4–60.5 mic, respectively.ConclusionsThe results of this study showed that although repeated measurements of the CCT with Orbscan and Pentacam are strongly correlated, repeatability values of CCT measurements significantly decrease at more advanced grades of keratoconus. In all keratoconus grades, repeatability of CCT measurements was better with Pentacam than Orbscan. These findings indicate that corneal thickness readings have less validity in patients with advanced keratoconus.

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“…Measurement of central corneal thickness (CCT) is very important for screening, diagnosis, and management of many ophthalmic conditions. [12] It gives information about corneal endothelial cells function, homogeneity of stroma, and patient eligibility to different techniques of refractive surgery and laser vision correction. [34]…”

Section: Introductionmentioning

confidence: 99%

Central corneal thickness measurement using ultrasonic pachymeter, optical coherence tomography, and TMS-5 topographer

et al. 2019

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AIM:This study aimed to compare the central corneal thickness (CCT) measurements using Optical Coherence Tomography (OCT) and TMS-5 topographer with that taken with the gold standard digital Ultrasonic pachymeter (USP).MATERIALS AND METHODS:A total of 61 subjects (122 eyes) were prospectively and consecutively studied in a period from June 2016 to June 2017 at Sudan Eye Centre (SEC), Khartoum, Sudan. Besides the visual and refractive data, measurements of CCT were taken using OCT, TMS-5 and USP. Data analyzed using SPSS software for windows (IBM SPSS 20, IBM Corp., Armonk, NY).RESULTS:A statistically significant differences in mean CCT was detected between the three instruments (P < 0.001). USP was found to measure the CCT 29μm thicker than OCT and 22μm thicker than TMS-5 topographer. A significant difference was also found between OCT and TMS-5. OCT found to give the lower values of CCT compared to both USP and TMS-5 topographer. Further analysis showed that the three procedures were significantly and strongly correlated to each other (USP vs OCT, r = 0.77), (USP vs TMS-5, r = 0.78) and (OCT vs TMS-5, r = 0.80).CONCLUSION:Mean central corneal thicknesses (CCT) were comparable among OCT, TMS-5 topographer and the gold standard USP. However, there is a reproducible systematic difference between CCT measurements taken with the three devices. It is important to note in clinical practice, that measurements acquired by these three modalities are not directly interchangeable.

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Repeatability of central corneal thickness measurement with the Pentacam HR system

Cited by 5 publications

References 17 publications

Pentacam HR Indices Variation in Normal Corneas with Different Corneal Thickness

Pentacam HR Indices Variation in Normal Corneas with Different Corneal Thickness

Corneal thickness measurements with Scheimpflug and slit scanning imaging techniques in keratoconus

Central corneal thickness measurement using ultrasonic pachymeter, optical coherence tomography, and TMS-5 topographer

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