Evaluation of the Reliability and Repeatability of Scheimpflug System Measurement in Keratoconus

Eguileor, Beatriz de Luis; Argaluza, Julene Escudero; Zubizarreta, J.; Carro, Alaitz Santamaria; Ecenarro, Jaime Etxebarria

doi:10.1097/ico.0000000000001373

Cited by 33 publications

(26 citation statements)

References 30 publications

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“…Many of the RLs found in the present study were lower than those in the de Luis Eguileor study 5 . This was especially true when all four of the devices image quality metrics were met.…”

Section: Discussioncontrasting

confidence: 86%

“…The Global Consensus on Keratoconus and Ectatic Disease defined ectatic progression by a consistent change, where the magnitude of the change is above the noise of the testing system 4 . In conforming to these guidelines, a study was published by de Luis Eguileor et al, which investigated the repeatability of measurements pertinent to the monitoring of progression in eyes with keratoconus using a Scheimpflug system (Pentacam HR) 5 . This study found that sequential measurements differing by more than 1.54 D, 1.08 D, and 0.71 ¼m in the steep keratometry, maximum keratometry, and vertical coma, respectively, likely represented real change.…”

Section: Introductionmentioning

confidence: 99%

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Repeatability of a Dual-Scheimpflug Placido Disc Corneal Tomographer/Topographer in Eyes with Keratoconus

Poulsen

Jang

Khan

et al. 2020

Preprint

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Purpose: To investigate the repeatability of a combined Dual-Scheimpflug placido disc corneal topographer (Zeimer Galilei G4) with respect to keratometric indices used to monitor progression of keratoconus (KCN). Methods: Patients with KCN were prospectively enrolled. For each eye lacking history of corneal surgery, 5 measurements were taken in succession. Eyes in which 3 or more measurements could be obtained (defined by the device's 4 image quality metrics) were included in the analysis. The repeatability limits (RL) and interclass correlation coefficients (ICC) were calculated for various parameters. Results: 32 eyes from 25 patients met all image quality metrics, and 54 eyes from 38 patients met at least 3/4 criteria (all except the placido image quality metric). RLs for key parameters when 4/4 or 3/4 image quality metrics were met included: 0.37 and 0.77 diopters (D) for steep simulated keratometry, 0.79 and 1.65 D for maximum keratometry, 13.80 and 13.88 degrees for astigmatism axis, 0.64 and 0.56 um for vertical coma magnitude, and 3.76 and 3.84 um for thinnest pachymetry, respectively. The ICCs for all parameters were excellent [above 0.87 except for spherical aberration (0.77)]. Conclusions: The dual-Scheimpflug placido disc corneal topographer is highly repeatable in quantifying parameters used in monitoring KCN. Excellent placido images are difficult to capture in eyes with KCN, but when available, increase the reliability of the measurements. The RLs may be especially helpful in detecting progression in mild KCN when interventions such as corneal cross-linking or intrastromal corneal ring segments are most beneficial.

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“…Many of the RLs found in the present study were lower than those in the de Luis Eguileor study 5 . This was especially true when all four of the devices image quality metrics were met.…”

Section: Discussioncontrasting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Repeatability of a Dual-Scheimpflug Placido Disc Corneal Tomographer/Topographer in Eyes with Keratoconus

Poulsen

Jang

Khan

et al. 2020

Preprint

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“…The technical features of this system have been described elsewhere. 5 We used the default setting of 25 pictures/s. The Nidek ARK 560-A (Nidek Co Ltd, Tokyo, Japan) is a combined refractometer and keratometer.…”

Section: Instrumentsmentioning

confidence: 99%

“…Several studies have been carried out to investigate RC in measurements of the parameters used in the detection of progressive keratoconus. [4][5][6][7] However, RC is usually calculated based on measurements on the same day, rather than on different days. 8 The evaluation of the interday repeatability in subjects with keratoconus is thus of the utmost importance, as progression is diagnosed over time.…”

mentioning

confidence: 99%

The Interday Repeatability of Parameters for the Assessment of Progressive Disease in Subjects With Less Advanced Keratoconus

Gustafsson

Bergström

Cardiakides

et al. 2021

American Journal of Ophthalmology

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To evaluate the interday repeatability in the measurement of parameters used for the detection of progression of keratoconus by prediction limits (PL) for single measurements, and the repeatability coefficient (RC) for the mean of replicate measurements.DESIGN: Prospective reliability analysis for cases and control eyes.METHODS: Twenty-five eyes in 25 subjects with KC and 25 eyes in 25 healthy controls were included. Four consecutive measurements were made, 3 days apart, with a Pentacam HR tomographic instrument (denoted the Pentacam) and a Nidek ARK 560-A autokeratometer (denoted the keratometer). Main outcome measures were the intra-and interday RC of parameters used in the detection of progression of keratoconus.RESULTS: The most repeatable parameter obtained with the Pentacam was the curvature power of the central flat meridian (K1, 0.44 D [RC], -0.55 to 0.60 diopter [D] [PL]), followed by the central steep meridian (K2, 0.72 D [RC], -0.90 to 0.94 D [PL]). The interday repeatability of K1 and K2 was similar when using the keratometer (K1, 0.32 D [RC], -0.66 to 0.57 D [PL], K2, 0.93 D [RC], -1.36 to 1.08 D [PL]). The interday repeatability of the curvature power of the steepest point (Kmax, 0.84 D [RC], -0.90 to 1.11 D [PL]) would benefit from being stratified: RC [ 0.44 D and PL [ -0.49 to 0.67 D for Kmax < 49.0 D, and RC [ 1.08 D and PL [ -1.19 to 1.42 D for Kmax ‡ 49.0 D. CONCLUSIONS:The interday repeatability of measurements, single or replicate, in subjects with keratoconus should be considered when diagnosing progressive disease. K1 exhibited the best intraday repeatability. Kmax benefits from being stratified according to disease severity.

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“…Classicamente, inicia-se na puberdade e progride até a quarta década de vida, quando geralmente se estabiliza. (3) O diagnóstico é feito por exame clínico e avaliação tomográfica da córnea. Os sinais tomográficos da doença incluem: aumento da curvatura anterior da córnea, astigmatismo irregular e assimétrico, afinamento estromal e aumento da curvatura posterior.…”

Section: Introductionunclassified

Análise comparativa entre os índices tomográficos em pacientes com ceratocone inicial

Rodrigues¹,

Vilela²,

Nishi³

et al. 2021

Revista Brasileira De Oftalmologia

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Evaluation of the Reliability and Repeatability of Scheimpflug System Measurement in Keratoconus

Cited by 33 publications

References 30 publications

Repeatability of a Dual-Scheimpflug Placido Disc Corneal Tomographer/Topographer in Eyes with Keratoconus

Repeatability of a Dual-Scheimpflug Placido Disc Corneal Tomographer/Topographer in Eyes with Keratoconus

The Interday Repeatability of Parameters for the Assessment of Progressive Disease in Subjects With Less Advanced Keratoconus

Análise comparativa entre os índices tomográficos em pacientes com ceratocone inicial

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