Table 5 Mean arithmetic values and power vectors for total corneal refractive power at 2.0–5.0 mm rings

Centered on pupil

Mean keratometry (diopter)

44.51 ± 1.41

44.70 ± 1.21

44.88 ± 1.10

45.00 ± 1.06

< 0.001

49.35 ± 4.30

48.52 ± 3.31

47.56 ± 2.38

46.54 ± 2.06

< 0.001

Mean

arithmetic

astigmatism (diopter)

2.96 ± 1.07

3.10 ± 1.26

3.15 ± 1.47

2.96 ± 1.46

0.20

5.58 ± 2.31

5.55 ± 2.30

5.16 ± 2.44

4.19 ± 2.49

< 0.001

KP(0) (diopter)

−1.58 ± 2.12

−2.09 ± 2.05

− 2.45 ± 1.99

−2.51 ± 1.75

0.10

− 3.35 ± 3.85

− 3.67 ± 3.98

− 3.65 ± 3.81

−3.00 ± 3.36

0.15

KP(45) (diopter)

1.11 ± 1.37

1.09 ± 1.26

0.98 ± 1.13

0.85 ± 0.92

0.44

1.51 ± 2.94

0.91 ± 2.53

0.46 ± 2.20

0.26 ± 1.92

0.001

Centered on apex

Mean keratometry (diopter)

45.09 ± 1.43

45.13 ± 1.26

45.22 ± 1.11

45.17 ± 1.15

0.97

50.80 ± 4.91

49.45 ± 3.67

48.06 ± 2.46

46.86 ± 1.64

< 0.001

Mean

arithmetic

astigmatism (diopter)

3.15 ± 1.28

3.09 ± 1.12

3.00 ± 1.31

2.66 ± 1.31

0.005

5.86 ± 2.66

4.94 ± 2.30

4.22 ± 2.14

3.43 ± 1.88

< 0.001

KP(0) (diopter)

−1.56 ± 2.42

−1.92 ± 2.20

−2.20 ± 2.07

−2.18 ± 1.73

0.16

− 3.44 ± 4.13

−3.04 ± 3.55

− 2.61 ± 3.22

−2.14 ± 2.77

0.32

KP(45) (diopter)

1.20 ± 1.45

0.98 ± 1.21

0.79 ± 1.06

0.62 ± 0.89

0.12

1.75 ± 3.16

1.19 ± 2.62

0.79 ± 2.20

0.57 ± 1.70

0.002

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

0.10

0.78

< 0.001

< 0.001

0.25

0.017

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

0.022

0.99

0.06

0.004

0.032

0.006

< 0.001

< 0.001

0.63

0.030

0.003

< 0.001

0.60

< 0.001

< 0.001

< 0.001

0.52

0.050

0.005

0.002

0.009

0.024

0.020

0.076