Table 2.
The best parameters (highest AUROC) differentiating early keratoconus (FFKC, SCKC, KC suspect) from normal eyes, along with the AUROC, sensitivity, specificity, and cut-off values
| Author | Year | Modality | Parameter with highest AUROC | AUROC (%) | Cut-off value | Sensitivity (%) | Specificity (%) |
|---|---|---|---|---|---|---|---|
| FFKC vs. Normal | |||||||
| Temstet [47] | 2015 | AS-OCT (RTVue) | Epithelial thickness in the thinnest corneal zone | 79.5 | 52 | 88.9 | 59.5 |
| Naderan [13] | 2018 | Aberrometry (OPD-Scan II) | Ocular total HOA | 90.8 | 0.306 | 91.7 | 95.3 |
| Itoi [37] | 2020 | AS-OCT (CASIA) | As/Ps | 98 | 0.99 | 92 | 96 |
| Thulasides [10] | 2020 | Rotating Scheimpflug (Pentacam) | BAD-D | 85.9 | 0.835 | 93.3 | 32.4 |
| Elkitkat [29] | 2021 | Rotating Scheimpflug (Pentacam) | PE from BFTE | 98.9 | > 4 | 96 | 96.15 |
| Toprak [51] | 2021 | AS-OCT (MS-39) | Epith/Stromal thickness ratio | NA | NA | 75 | 94.3 |
| Sedaghat [70] | 2023 | NCT/Scheimpflug (Corvis ST) | TBI | 96.6 | NA | NA | NA |
| Gharieb [30] | 2024 | Rotating Scheimpflug (Sirius) | KVf | 83.1 | NA | NA | NA |
| SCKC vs. Normal | |||||||
| Li [45] | 2016 | AS-OCT (RTVue) | Epithelial PSD | 98.5 | > 0.041 | 96 | 100 |
| Xu [46] | 2016 | UHR-OCT (Custom-built) | EEI-MAX and BEI-MAX | 97 | NA | 91 | 93 |
| Shetty [26] | 2017 | Rotating Scheimpflug (Pentacam) | BAD-D | 88.7 | > 1.6 | 83.8 | 86 |
| Golan [11] | 2018 | Rotating Scheimpflug (Galilei) | MPE at BFTA | 87.7 | 11.5 | 79.5 | 84.8 |
| Koc [28] | 2018 | Rotating Scheimpflug (Pentacam) | Corneal densitometry (anterior layer, 0–2 zone) | 88.3 | 19.7 | 75 | 90 |
| Castro-Luna [86] | 2020 | Rotating Scheimpflug (Pentacam) | MCT, anterior & posterior coma to 90° | 92 | NA | 75 | 96.34 |
| Heidari [85] | 2020 | Rotating Scheimpflug (Sirius) | BCVf | 87.7 | NA | 87.7 | 83 |
| Heidari [27] | 2021 | Rotating Scheimpflug (Sirius) | SIb | 90.8 | NA | 86.2 | 84.9 |
| Toprak [51] | 2021 | AS-OCT (MS-39) | Epith/Stromal thickness ratio | NA | NA | 94 | 98.5 |
| Peyman [73] | 2023 | NCT/Scheimpflug (Corvis ST) | TBI | 85.8 | > 0.33 | 78.08 | 76.81 |
| Randleman [78] | 2023 | MT Brillouin microscopy | Mean plateau | 100 | < 5.696 | 100 | 100 |
| Minimum plateau | 100 | < 5.679 | 100 | 100 | |||
| Mean anterior 150 μm | 100 | < 5.702 | 100 | 100 | |||
| Minimum anterior 150 μm | 100 | < 5.684 | 100 | 100 | |||
| Heidari [52] | 2024 | AS-OCT (Spectralis) | CCT | 78.2 | 548 | 75 | 64.1 |
| Suspect KC vs. Normal | |||||||
| Scuderi [38] | 2021 | AS-OCT (RTVue) | C1–C2 | 98.5 | NA | 94.74 | 94 |
| Salman [23] | 2022 | Rotating Scheimpflug (Sirius) | SIb | 86 | 0.12 | NA | 84.66 |
| Salman [87] | 2022 | Rotating Scheimpflug (Sirius) | RMS coma (3, ± 1) | 92.2 | > 0.2 | 95.24 | 75 |
AUROC = the area under the receiver operating characteristic curves; FFKC = forme fruste keratoconus; SCKC = subclinical keratoconus; KC = keratoconus; AS-OCT = anterior segment optical coherence tomography; HOA = higher-order aberrations; As/Ps = anterior/posterior corneal surface areas ratio; BAD-D = Belin-Ambrósio enhanced ectasia display deviation; PE = posterior elevation; BFTE = best-fit toric ellipsoid; NCT = non-contact tonometry; TBI = tomographic/biomechanical index; KVf = keratoconus vertex front; PSD = pattern standard deviation; EEI-MAX = maximum epithelium ectasia index; BEI-MAX = maximum Bowman’s layer ectasia index; MPE = maximum posterior elevation; BFTA = best-fit toric aspheric surface; MCT = minimal corneal thickness; BCVf = Baiocchi Calossi Versaci front; MT = motion tracking; SIb = symmetry index back; CCT = central corneal thickness; RMS = root mean square