Screening for Keratoconus With New Dynamic Biomechanical In Vivo Scheimpflug Analyses

Steinberg, Johannes; Katz, Toam; Lücke, Kristina; Фрингс, Андреас; Druchkiv, Vasyl; Linke, Stephan J.

doi:10.1097/ico.0000000000000598

Cited by 59 publications

(37 citation statements)

References 24 publications

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“…Although most of these parameters were significantly different in keratoconus and normal corneas, the overall AUC was less than 0.80 indicating insufficient predictive accuracy 23. Steinberg et al introduced ‘applanation length level’ and ‘deflection length level’ using Corvis, but they were also limited by a low discriminative power 27. In our study, we used a new Corvis software and identified novel parameters, namely DA ratio 2 (AUC 0.946), DA ratio 1 (AUC 0.937) and maximum inverse radius (AUC 0.954).…”

Section: Discussionmentioning

confidence: 99%

Comparison of corneal dynamic parameters and tomographic measurements using Scheimpflug imaging in keratoconus

Chan

Wang

et al. 2017

Br J Ophthalmol

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Section: Discussionmentioning

confidence: 99%

Comparison of corneal dynamic parameters and tomographic measurements using Scheimpflug imaging in keratoconus

Chan

Wang

et al. 2017

Br J Ophthalmol

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“…Most earlier studies produced an AUC lower than 0.900, [19][20][21] even though some of these studies refer to subclinical cases. 22 However, the dynamic Scheimpflug Corvis ST device is relatively new.…”

Section: Discussionmentioning

confidence: 99%

Detection of Keratoconus With a New Biomechanical Index

Vinciguerra¹,

Ambrósio²,

Elsheikh³

et al. 2016

J Refract Surg

412

346

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he early diagnosis of corneal ectasia is of foremost importance in both screening for refractive surgery and the early treatment of keratoconus. Topography or tomography analysis using either videokeratography or optical coherence tomography instruments can help detect alteration in the shape of the cornea such as thinning and increased curvature. However, these instruments cannot measure the mechanical stability, which is thought to be the initiating event of the disease, even before notable changes in corneal morphology take place.1,2 For this reason, there has been increasing interest in developing instruments to measure the in vivo biomechanical properties of the cornea to aid the diagnosis of an ectasia in a "biomechanical" stage, when topography and tomography are nor-T ABSTRACT PURPOSE: To evaluate the ability of a new combined biomechanical index called the Corvis Biomechanical Index (CBI) based on corneal thickness profile and deformation parameters to separate normal from keratoconic patients.METHODS: Six hundred fifty-eight patients (329 eyes in each database) were included in this multicenter retrospective study. Patients from two clinics located on different continents were selected to test the capability of the CBI to separate healthy and keratoconic eyes in more than one ethnic group using the Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). Logistic regression was employed to determine, based on Database 1 as the development dataset, the optimal combination of parameters to accurately separate normal from keratoconic eyes. The CBI was subsequently independently validated on Database 2. RESULTS:The CBI included several dynamic corneal response parameters: deformation amplitude ratio at 1 and 2 mm, applanation 1 velocity, standard deviation of deformation amplitude at highest concavity, Ambrósio's Relational Thickness to the horizontal profile, and a novel stiffness parameter. The receiver operating characteristic curve analysis of the training database showed an area under the curve of 0.983. With a cut-off value of 0.5, 98.2% of the cases were correctly classified with 100% specificity and 94.1% sensitivity. In the validation dataset, the same cut-off point correctly classified 98.8% of the cases with 98.4% specificity and 100% sensitivity. CONCLUSIONS:The CBI was shown to be highly sensitive and specific to separate healthy from keratoconic eyes. The presence of an external validation dataset confirms this finding and suggests the possible use of the CBI in everyday clinical practice to aid in the diagnosis of keratoconus.[J Refract Surg. 2016;32(12):803-810.]

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“…Also, the analyzed CST parameters failed to detect abnormalities in the cases referred to as having subclinical disease. 1 However, we do have a few comments that should provide a positive insight into this important subject for our field.…”

Section: To the Editormentioning

confidence: 99%

“…Normal topography was defined as KISA less than 60%, I-S less than 1.4D, and Kmax less than 47D. 1 Even though this is relatively rare, it is possible that some of these cases have mild or susceptible forms of ectasia, because there are reported cases that, despite having normal topography and central corneal thickness, progressed to keratectasia after laser-assisted in situ keratomileusis (LASIK) 10,11 or photorefractive keratectomy. 12 Considering the preoperative state of stable LASIK cases with longterm follow-up would provide a more robust population for the normal control group.…”

Section: To the Editormentioning

confidence: 99%

“…1.4D), but with KISA less than 100%. 1 Interestingly, the stability of LASIK in corneas with such characteristics has been reported because these eyes may be classified as nonkeratoconic by segmental or layered tomographic epithelial thickness mapping. 15 The study also included 27 cases considered as sub-clinical keratoconus, defined as the eye with normal topography (KISA , 60%, I-S , 1.4 D, and Kmax , 47D) from patients with clinical ectasia detected in the fellow eye.…”

Section: To the Editormentioning

confidence: 99%

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Ectasia Detection by the Assessment of Corneal Biomechanics

Ambrósio

Lopes

Faria-Correia

et al. 2016

Cornea

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FIGURE 1. Novel parameters from CST derived from the analysis of the highest concavity phase. A, DA ratio 2 mm describes the ratio between deformation amplitude at apex and at 2 mm (greens arrows). B, Inverse concave radius represents the inverse concave radius of curvature (1/r). The graphs of DA ratio 2 mm and inverse concave radius are plotted over time with the indication of applanation of the cornea during ingoing (A1) and outgoing (A2) phases.

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Screening for Keratoconus With New Dynamic Biomechanical In Vivo Scheimpflug Analyses

Abstract: In vivo biomechanical analyses (CST) at their current state only marginally improve KC screening protocols. Newly generated parameters such as the applanation length level and deflection length level might further improve early KC screening.

Cited by 59 publications

References 24 publications

Comparison of corneal dynamic parameters and tomographic measurements using Scheimpflug imaging in keratoconus

Comparison of corneal dynamic parameters and tomographic measurements using Scheimpflug imaging in keratoconus

Detection of Keratoconus With a New Biomechanical Index

Ectasia Detection by the Assessment of Corneal Biomechanics

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