Table 1: Patient demographics compared with 5 other published studies.

Present Guan et al. [12]Chen et al. [8]Ferrer-Blasco et al. [7] Khan and Muhtaseb [5]De Bernardo
et al. [14]

Eyes/patients12449/69081430/8274831/28494540/24151230/746757/380
Age (y)
 Mean ± SD69.80 ± 11.1572.27 ± 11.5970.56 ± 9.5560.59 ± 9.8775.54 ± 0.7171.89 ± 10.19
 Range30, 9716, 9849, 9532, 8730, 10433, 96
Male/female3199/3709359/4681090/1759768/1647343/403176/204
Corneal astigmatism (D)
 Mean ± SD1.15 ± 0.841.07 ± 0.731.01 ± 0.690.90 ± 0.931.03 ± 0.731.02 ± 0.69
 Range0.0, 6.630.06, 5.520.05, 6.590.25, 6.750.0, 6.20.06, 4.57
K1 mean ± SD43.93 ± 1.6743.57 ± 1.5643.76 ± 1.5343.48 ± 1.6143.43 ± 1.4943.54 ± 1.43
K2 mean ± SD45.08 ± 1.7344.64 ± 1.6544.76 ± 1.5644.08 ± 1.5944.46 ± 1.5644.56 ± 1.52
Corneal astigmatism (%)
 ≤0.5 D20.7621.2*23.1458.824.4723.38
 ≥1.0 D47.2745.3741.334.840.441.74
 ≥2.0 D13.1610.338.229.26**9.678.32
 ≥3.0 D3.752.223.525.61***4.612.64

Not including 0.5 D, not including 2.0 D, and not including 3.0 D.
D = diopter, K1 = flat keratometry, and K2 = steep keratometry.