Table 2.
The Clinically Suggested Cutoff Values for Keratoconus Indices in Screening Clinical and Subclinical Cases
| Parameter | Clinical Keratoconus | Subclinical Keratoconus |
|---|---|---|
| Tomographic | ||
| CKI | ∗ | ∗ |
| KI | 1.07 | ∗ |
| IHA | 10.4 | ∗ |
| IHD | 0.017 | ∗ |
| TKC | 1.0 | 2.0 |
| ISV | 36.6 | ∗ |
| IVA | 0.28 | 0.15 |
| Rmin | 7.04 | ∗ |
| PE | 20.5 | 10.5 |
| IS value | 1.1 | 1.9 |
| KISA | 60% | 100% |
| Pachymetric | ||
| ART-Min | 606 | ∗ |
| ART-Max | 356 | 368 |
| ART-Avg | 444 | 490 |
| BAD_D | 2.02 | 1.31 |
| CCT | 515 | 518 |
| PPI-Min | 0.87 | 0.80 |
| PPI-Max | 1.53 | 1.40 |
| PPI-Avg | 1.18 | 1.08 |
| TCT | 506 | 502 |
∗ = although several studies have addressed the values of these parameters, clear cutoffs have not been achieved; ART = Ambrosio's relational thickness indices; BAD_D = Belin/Ambrósio deviation; CCT = central corneal thickness; CKI = central keratoconus index; IHA = index of height asymmetry; IHD = index of highest decentration; IS value = the inferior–superior value; ISV = index surface variance; IVA = index of vertical asymmetry; KI = keratoconus index; KISA = The KISA index was derived from the following 4 indices: central K; I-S; the SRAX index, an expression of irregular astigmatism occurring in keratoconus; and the astigmatism index, which quantifies the degree of the regular corneal astigmatism (simulated K1 − simulated K2); PE = prediction error; PPI = pachymetric progression indices; Rmin = minimum radius of curvature; TCT = thinnest corneal thickness; TKC = topographic keratoconus classification.