Repeatability of the Pentacam HR in Various Grades of Keratoconus

Kreps, Elke O.; Jiménez‐García, Marta; Issarti, Ikram; Claerhout, Ilse; Koppen, Carina; Rozema, Jos J

doi:10.1016/j.ajo.2020.06.013

Cited by 62 publications

(96 citation statements)

References 29 publications

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“…In that study, we suggested the stratification of detection limits for different parameters according to disease severity. This has also recently been proposed by other authors 11 . In a more recent study, we presented the inter-day repeatability of measurements in subjects with keratoconus and in healthy controls, using the Pentacam HR 12 .…”

Section: Introductionsupporting

confidence: 81%

“…The threshold for C is at approximately 500 µm, below which measurements are more prone to error. It was also reported in a recent study that the repeatability of measurements of A, B and C deteriorated with increasing disease severity 11 . However, those calculations were based on intra-day measurements, and the association between deteriorating repeatability and disease severity was not investigated per se.…”

Section: Discussionmentioning

confidence: 57%

“…The latter could be appropriate in subjects with less severe keratoconus, as the repeatability of these measurements will probably be more similar to those in a healthy cohort than a general cohort of patients with all stages of disease. In fact, in the abovementioned study 11 the repeatability of measurements of A, B and C was reported to be identical in healthy subjects and in subjects with subclinical keratoconus. However, there will be a threshold at which some subjects with keratoconus will be over-diagnosed as progressive if compared to a healthy cohort.…”

Section: Discussionmentioning

confidence: 59%

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An inter-day assessment of the ABC parameters in the evaluation of progressive keratoconus

Gustafsson

Faxén

Vicente

et al. 2021

Sci Rep

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The progression of keratoconus is commonly determined by comparing the results of corneal tomographic measurements on different occasions. However, investigations on the repeatability of measurements are commonly performed within the same day, thus not taking the inter-day variation into account. The effect of keratoconus disease severity on the measurement error is also seldom considered. In this post hoc investigation, the parameters A, B and C in the Belin ABCD Progression Display were evaluated in relation to disease severity in intra-day and inter-day measurements. Four consecutive measurements were performed on 61 patients with keratoconus on the same day (intra-day). In another cohort, four consecutive measurements were obtained and then repeated 3 days later in 25 patients with keratoconus and 25 healthy controls (inter-day). The results suggest that the diagnosis of disease progression would benefit from inter-day measurements, and the stratification of the parameters A and C according to disease severity. It is also recommended that tomographic systems such as the Pentacam HR be modified to allow the comparison of both single measurements and the mean of replicate measurements of the parameters used in the assessment of progression of keratoconus.

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Section: Introductionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 57%

Section: Discussionmentioning

confidence: 59%

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An inter-day assessment of the ABC parameters in the evaluation of progressive keratoconus

Gustafsson

Faxén

Vicente

et al. 2021

Sci Rep

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“…The minimally detectable change is directly linked to the repeatability of the parameters provided by Pentacam in KC, which was recently reported [ 6 ]. Repeatability is defined as r = S w × 1.96 × √2, where S w is the within-subject standard deviation, and the difference between two measurements for the same subject is expected to be <2.77 × S w for 95% of the pairs of observations [ 28 ].…”

Section: Methodsmentioning

confidence: 82%

“…Given this complex context, it is hardly surprising that clinicians cannot form a consensus on a common definition of clinical progression. Nevertheless, definitions for progression have been established based on the repeatability of the clinical devices, which determines the minimum change measurable at a pre-established significance level, keeping in mind that repeatability is worse in keratoconic corneas [ 6 ]. This approach was recently introduced in the Pentacam ABCD progression display [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Forecasting Progressive Trends in Keratoconus by Means of a Time Delay Neural Network

Jiménez‐García

Issarti

Kreps

et al. 2021

JCM

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Early and accurate detection of keratoconus progression is particularly important for the prudent, cost-effective use of corneal cross-linking and judicious timing of clinical follow-up visits. The aim of this study was to verify whether a progression could be predicted based on two prior tomography measurements and to verify the accuracy of the system when labelling the eye as stable or suspect progressive. Data from 743 patients measured by Pentacam (Oculus, Wetzlar, Germany) were available, and they were filtered and preprocessed to data quality needs. The time delay neural network received six features as input, measured in two consecutive examinations, predicted the future values, and determined the classification (stable or suspect progressive) based on the significance of the change from the baseline. The system showed a sensitivity of 70.8% and a specificity of 80.6%. On average, the positive and negative predictive values were 71.4% and 80.2%. Including data of less quality (as defined by the software) did not significantly worsen the results. This predictive system constitutes another step towards a personalized management of keratoconus. While the results obtained were modest and perhaps insufficient to decide on a surgical procedure, such as cross-linking, they may be useful to customize the timing for the patient’s next follow-up.

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Indikationsstellung zum Crosslinking und klinische Ergebnisse neuer kornealer Crosslinking-Techniken

et al. 2022

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Repeatability of the Pentacam HR in Various Grades of Keratoconus

Cited by 62 publications

References 29 publications

An inter-day assessment of the ABC parameters in the evaluation of progressive keratoconus

An inter-day assessment of the ABC parameters in the evaluation of progressive keratoconus

Forecasting Progressive Trends in Keratoconus by Means of a Time Delay Neural Network

Indikationsstellung zum Crosslinking und klinische Ergebnisse neuer kornealer Crosslinking-Techniken

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