Table 2.
Measurement of repeatability of OQAS-II parameters for the normal group, FFK, AK1, and AK2.
| NL | FFK | AK1 | AK2 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ICC | RC | CVw (%) | ICC | RC | CVw (%) | ICC | RC | CVw (%) | ICC | RC | CVw (%) | |
| OSI | 0.973 (0.944 to 0.988) | 0.152 | 12.448 | 0.968 (0.935 to 0.986) | 0.303 | 18.053 | 0.994 (0.988 to 0.997) | 0.971 | 12.306 | 0.934 (0.864 to 0.971) | 4.740 | 17.319 |
| MTF cutoff (c/d) | 0.965 (0.929 to 0.985) | 5.472 | 4.231 | 0.915 (0.824 to 0.963) | 12.289 | 11.432 | 0.953 (0.903 to 0.979) | 10.879 | 17.877 | 0.792 (0.570 to 0.909) | 9.840 | 49.131 |
| SR | 0.868 (0.726 to 0.942) | 0.088 | 11.712 | 0.887 (0.766 to 0.951) | 0.088 | 14.011 | 0.950 (0.897 to 0.978) | 0.088 | 24.325 | 0.770 (0.525 to 0.900) | 0.088 | 52.705 |
| OV-100 | 0.966 (0.930 to 0.985) | 0.175 | 4.054 | 0.915 (0.823 to 0.963) | 0.411 | 11.471 | 0.953 (0.904 to 0.980) | 0.361 | 17.861 | 0.791 (0.568 to 0.909) | 0.328 | 49.301 |
| OV-20 | 0.957 (0.912 to 0.981) | 0.232 | 6.915 | 0.910 (0.813 to 0.961) | 0.361 | 13.725 | 0.963 (0.921 to 0.984) | 0.248 | 18.254 | 0.779 (0.543 to 0.903) | 0.232 | 52.291 |
| OV-9 | 0.928 (0.851 to 0.969) | 0.215 | 10.328 | 0.900 (0.794 to 0.956) | 0.248 | 15.227 | 0.947 (0.891 to 0.977) | 0.175 | 21.809 | 0.785 (0.555 to 0.906) | 0.152 | 54.772 |
NL: normal; FFK: forme fruste keratoconus; AK1: stage 1 of the Amsler-Krumeich scales; AK2: stage 2 of the Amsler-Krumeich scales; ICC: intraclass correlation coefficient; RC: Repeatability; CVw: coefficient of variation; OSI: object scatter index; MTF cutoff: modulation transfer function cutoff; SR: Strehl ratio; OV-100: OQAS values at contrasts of 100%; OV-20: OQAS values at contrasts of 20%; OV-9: OQAS values at contrasts of 9%.