Table 3. Agreement between Placido disk-based topography and high-resolution rotating Scheimpflug camera in measuring corneal power in eyes with keratoconus.
| Instruments | Kf | Ks | Km | Ks-Kf |
| Placido | 44.63±1.65 | 47.76±3.06 | 46.12±2.23 | 3.14±1.92 |
| Scheimpflug | 44.99±1.81 | 47.95±3.05 | 46.41±2.33 | 2.96±1.63 |
| 1P | <0.01 | 0.03 | <0.01 | 0.26 |
| Difference between instruments | -0.37±0.47 | -0.19±0.60 | -0.29±0.40 | 0.18±0.66 |
| 95% LoA | -1.28 to +0.55 | -1.36 to +0.99 | -1.08 to +0.50 | -1.11 to +1.48 |
Kf: Flat keratometry; Ks: Steep keratometry; Km: Mean keratometry; Ks-Kf: Astigmatism; 95% LoA: 95% limits of agreement. 1Wilcoxon's signed-rank test.
x±s