Table 2 Mean arithmetic values and power vectors for total corneal refractive power within 2.0–5.0 mm zones
From: Analysis of total corneal astigmatism with a rotating Scheimpflug camera in keratoconus
2.0 mm zone | 3.0 mm zone | 4.0 mm zone | 5.0 mm zone | * p value | ||
|---|---|---|---|---|---|---|
Centered on pupil | Mean keratometry (diopter) | 48.28 ± 5.19 | 47.96 ± 4.53 | 47.62 ± 3.83 | 47.20 ± 3.15 | 0.005 |
Mean arithmetic astigmatism (diopter) | 3.62 ± 2.50 | 4.32 ± 2.11 | 4.52 ± 1.99 | 4.41 ± 1.97 | < 0.001 | |
KP(0) (diopter) | − 1.70 ± 2.72 | − 2.42 ± 3.09 | − 2.83 ± 3.23 | − 2.99 ± 3.13 | < 0.001 | |
KP(45) (diopter) | 1.44 ± 2.66 | 1.38 ± 2.45 | 1.21 ± 2.16 | 1.05 ± 1.91 | 0.17 | |
Centered on apex | Mean keratometry (diopter) | 49.83 ± 5.92 | 49.29 ± 5.16 | 48.68 ± 4.31 | 48.03 ± 3.99 | < 0.001 |
Mean arithmetic astigmatism (diopter) | 5.35 ± 3.16 | 5.02 ± 2.66 | 4.61 ± 2.16 | 4.15 ± 1.81 | < 0.001 | |
KP(0) (diopter) | −2.64 ± 4.15 | −2.70 ± 3.75 | −2.68 ± 3.30 | −2.59 ± 2.87 | 0.32 | |
KP(45) (diopter) | 1.72 ± 3.43 | 1.53 ± 2.97 | 1.35 ± 2.49 | 1.12 ± 2.12 | 0.001 | |
** p value for mean keratometry | < 0.001 | < 0.001 | < 0.001 | < 0.001 | ||
** p value for mean arithmetic astigmatism | < 0.001 | < 0.001 | 0.62 | 0.07 | ||
** p value for KP(0) | 0.025 | 0.60 | 0.19 | 0.002 | ||
** p value for KP(45) | 0.011 | 0.076 | 0.068 | 0.36 | ||