Repeatability and Agreement of Three Scheimpflug-Based Imaging Systems for Measuring Anterior Segment Parameters in Keratoconus

Shetty, Rohit; Arora, Vishal; Jayadev, Chaitra; Nuijts, Rudy M.M.A.; Kumar, Mukesh; Puttaiah, Narendra K.; Kummelil, Mathew Kurian

doi:10.1167/iovs.14-15055

Cited by 99 publications

(86 citation statements)

References 26 publications

(33 reference statements)

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“…This might be due to the Scheimpflug technology being used by the two imaging systems, which is consistent with an earlier report in keratoconus eyes. [11] Our results showed that the COV values determined for the fKm and sKm with Sirius were lower compared to the previous reports in healthy eyes[12] indicating a lower frequency of distribution. Fixed bias was present in all the paired comparisons in keratometry except Sirius-Pentacam, while Orbscan consistently underestimated fKm and overestimated sKm.…”

Section: Discussioncontrasting

confidence: 66%

Repeatability and agreement of five imaging systems for measuring anterior segment parameters in healthy eyes

Kumar

Shetty

Jayadev

et al. 2017

Indian J Ophthalmol

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Purpose:The purpose of this study is to assess the repeatability and agreement of five imaging devices, namely, the Pentacam (Oculus), Sirius (CSO), Orbscan IIz (Bausch and Lomb), Corvis (Oculus), and ultrasound pachymetry (UP, Tomey) in measuring steep keratometry (sKm), flat keratometry (fKm), central corneal thickness (CCT), thinnest corneal thickness (TCT), and anterior chamber depth (ACD) in healthy individuals.Design:This was prospective, comparative study.Subjects:Forty-six healthy Indian patients.Materials and Methods:Forty-six eyes of 46 healthy participants underwent three consecutive scans on each device by a single examiner. Within-subject standard deviation, test–retest repeatability (TRT), and coefficient of variation (COV) for assessing repeatability and Bland–Altman plots for the agreement between the mean measurements of each machine were analyzed.Main Outcome Measures:The repeatability and agreement between the five devices for the measurements of sKm, fKm, CCT, TCT, and ACD.Results:The TRT of sKm measurements ranged between 0.23 diopter (D) (with Pentacam) and 0.83 D (with Orbscan). The same of fKm, TCT, ACD, and CCT measurements ranged between 0.28 D (with Pentacam) and 0.74 D (with Sirius), 7.78 μm (Sirius) and 19.81 μm (Orbscan), 0.05 mm (Orbscan) and 0.07 (Sirius), and 7.36 μm (Sirius) and 18.02 μm (Orbscan), respectively. The TRT of sKm and fKm measurements with Pentacam was significantly lower than those with Orbscan and Sirius. The TRT of TCT measurement with Sirius was significantly lower than that with Pentacam (4.53 μm) and Orbscan (7.15 μm). There were statistically significant differences in the mean measurements of all parameters between the devices. The 95% limit of agreement on the Bland–Altman analysis was wide for the measurement pairs with all the devices. Significant proportional bias in the agreement was detected for TCT measurements with all the device pairs and for the ACD measurements between Sirius and Pentacam.Conclusions:The repeatability estimates of sKm, fKm, TCT, ACD, and CCT measurements with Pentacam, Orbscan, Sirius, Corvis, and UP in Indian eyes were good. However, the differences in the measurements between the devices were statistically significant and the same cannot be used interchangeably for anterior segments measurements.

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Section: Discussioncontrasting

confidence: 66%

Repeatability and agreement of five imaging systems for measuring anterior segment parameters in healthy eyes

Kumar

Shetty

Jayadev

et al. 2017

Indian J Ophthalmol

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“…The Medmont-E300 has been shown to be highly repeatable on normal corneas,15 however, unlike other topography instruments,16 it has not been verified on keratoconic corneas. The surface irregularity of keratoconic corneas has been demonstrated to reduce repeatability of topography devices 17.…”

Section: Discussionmentioning

confidence: 99%

The natural history of corneal topographic progression of keratoconus after age 30 years in non-contact lens wearers

et al. 2016

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“…For each eye, three Pentacam measurements were taken, and the average value was recorded in the database. Pentacam measurements are shown to have excellent repeatability and reproducibility 18. All measurements were based on the data from the 3.0 mm annular corneal diameter ring.…”

Section: Methodsmentioning

confidence: 99%

Intereye asymmetry in bilateral keratoconus, keratoconus suspect and normal eyes and its relationship with disease severity

2017

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Repeatability and Agreement of Three Scheimpflug-Based Imaging Systems for Measuring Anterior Segment Parameters in Keratoconus

Cited by 99 publications

References 26 publications

Repeatability and agreement of five imaging systems for measuring anterior segment parameters in healthy eyes

Repeatability and agreement of five imaging systems for measuring anterior segment parameters in healthy eyes

The natural history of corneal topographic progression of keratoconus after age 30 years in non-contact lens wearers

Intereye asymmetry in bilateral keratoconus, keratoconus suspect and normal eyes and its relationship with disease severity

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