Evaluation of Scheimpflug Tomography Parameters in Subclinical Keratoconus, Clinical Keratoconus and Normal Caucasian Eyes

Abstract

Objectives:To evaluate tomographic and topographic parameters in subclinical and clinical keratoconus eyes by comparing them with normal eyes in a young Caucasian population.Materials and Methods:This cross-sectional study included 88 normal eyes (control group), bilateral data from the preclinical stage of 24 progressive keratoconus eyes (bilateral subclinical keratoconus group), 40 fellow eyes of patients with unilateral keratoconus (fellow eyes group) and 97 eyes with mild keratoconus (clinical keratoconus group). Topographic and tomographic data, data from enhanced elevation maps and keratoconus indices were measured in all study eyes using Scheimpflug tomography. Receiver operating characteristic (ROC) curve analysis was used to assess individual parameters to discriminate eyes of patients with subclinical and clinical keratoconus from control eyes. The sensitivity and specificity of the main effective parameters were evaluated and optimal cut-off points were identified to differentiate subclinical keratoconus and keratoconus from normal corneas.Results:Comparison of all subclinical and clinical keratoconus eyes from the normal group revealed significant differences in most diagnostic parameters. The ROC curve analysis showed high overall predictive accuracy of several Pentacam parameters (overall D value, anterior and posterior elevations and difference elevations, pachymetry progression index, index of surface variance, index of height decentration and keratoconus index) in discriminating ectatic corneas from normal ones. These outcomes were proportionally less pronounced in all subclinical keratoconus eyes than in the clinical keratoconus eyes. Pachymetric readings were progressively lower in the bilateral subclinical keratoconus eyes and sensitivity and specificity of the analyzed tomographic and topographic parameters were higher than the fellow eyes group when differentiating subclinical keratoconus from healthy corneas.Conclusion:Scheimpflug tomography parameters such as D value, elevation parameters, progression index and several surface indices can effectively differentiate keratoconus from normal corneas in a Caucasian population. Nevertheless, a combination of different data is required to distinguish subclinical keratoconus.

Subclinical keratoconus detection with three‐dimensional (3‐D) morphogeometric and volumetric analysis

“…The present study introduced a powerful formula with 96.8% sensitivity and 94.5% specificity in diagnosis subclinical KC based on morphogeometric, volumetric and clinical parameters (D apexant ‐D apexpost difference, VOL aap ‐1.0 mm, C x , cylinder, CCT and IOP). These sensitivity/specificity values seem to be higher than that of the Sirius KC screening standard algorithm (44.1% sensitivity and 96.3% specificity) and previously reported parameters in detection of subclinical KC (Pinero et al, 2010; Ucakhan et al, 2011; Cui et al, 2016; Hashemi et al, 2016; Huseynli & Abdulaliyeva, 2018; Chan et al, 2018). Furthermore, higher sample size can be considered as another strength of the current study.…”

“…Table 4 allows comparison of sample size, the best diagnostic parameter(s) and sensitivity/specificity values between the present study and previously published studies, which used similar subclinical KC definition with ours (Pinero et al, 2010; Ucakhan et al, 2011; Cui et al, 2016; Hashemi et al, 2016; Huseynli & Abdulaliyeva, 2018; Chan et al, 2018). Studies that included clinically and topographically normal (also no atypical or suspicious findings) fellow eye of a patient with manifest KC in the other eye (what corresponds to forme fruste KC definition) were not compared with our study to prevent bias, even if these eyes were defined as subclinical KC in those studies.…”

A predictive model for early diagnosis of keratoconus

“…Table 8 compares the results obtained with the Pentacam neural network to validate the ESKC model. [35] 68.40 84.60 0.839 Huseynli et al [9] 95.50 73.70 0.904 Hashemi et al [29] 81.10 73.20 0.860 Shetty et al [36] 83.80 86.00 0.887 Ruiseñor Vázquez et al [37] 89.20 82.30 0.930 Ambrósio et al [38] 93.60 94.60 0.975 Steinberg et al [39] 65.80 65.80 0.712 Muftuoglu et al [40] 60.00 90.00 0.834 Castro-Luna et al** 75.00 96.34 0.930 PPI-Avg [3] Cui et al [42] 94.70 89.70 0.957 Huseynli et al [9] 93.30 47.40 0.834 Shetty et al [36] 83.80 74.40 0.883 Ruiseñor Vázquez et al [37] 78.40 82.80 0.860 Muftuoglu et al [40] 77.00 65.00 0.806 Steinberg et al [39] 62.30 64.30 0.669 Uçakhan et al [41] 81.80 77.80 0.842 Castro-Luna et al** 75.00 90.24 0.850 IHD [3] Kovács et al [43] 80.00 75.00 0.880 Bae et al [44] 71.40 85.30 0.748 Huseynli et al [9] 82.30 65.00 0.782 Shetty et al [36] 43.20 67.40 0.627 Uçakhan et al [41] 75.00 60.30 0.703 Castro-Luna et al** 50.00 91.46 0.820 Art-MAX [3] Kovács et al [43] 84.00 54.00 0.740 Shetty et al [36] 86.50 69.80 0.850 Muftuoglu et al [40] 67.00 71.00 0.722 Ruiseñor Vázquez et al [37] 90.50 86.50 0.930 Ambrósio et al [38] 85.10 93.10 0.959 Steinberg et al [39] 30 [44] 71.40 61.80 0.733 Huseynli et al [9] 92.10 52.50 0.844 Hashemi et al [29] 82.30 73.20 0.860 Shetty et al [36] 10.80 95.30 0.609 Uçakhan et al [41] 86.40 61.90 0.768 Castro-Luna et al** 37.50 90.24 0.770 MCT [3] K...…”

A Case of Early Keratoconus Associated with Eye Rubbing in a Young Child

“…The current version is the BAD III, which utilizes nine tomographic parameters [11]. Studies have shown that among the keratometric, pachymetric, and posterior elevation indices, the D value has the highest area under the receiver operating characteristic curve in differentiating between clinical and subclinical keratoconus (SKC) eyes and control eyes [12,13].…”