Table 2: Descriptive statistics by age group.

Age group (y)Astigmatism (D)K1 (D) mean ± SDK2 (D) mean ± SDEyes (%)

30–401.33 ± 0.8542.77 ± 2.2344.10 ± 2.38164 (1.32)
41–501.10 ± 1.1043.51 ± 1.8344.61 ± 1.92571 (4.59)
51–600.99 ± 0.7143.91 ± 1.6144.90 ± 1.701869 (15.01)
61–701.05 ± 0.8044.04 ± 1.6345.10 ± 1.703226 (25.91)
71–801.20 ± 0.8343.95 ± 1.6545.14 ± 1.694517 (36.28)
81–901.34 ± 0.9043.95 ± 1.6845.28 ± 1.701993 (16.01)
≥911.39 ± 0.8243.73 ± 1.6545.12 ± 1.76109 (0.88)
<0.001<0.001<0.001<0.001

D = diopter, K1 = flat keratometry, and K2 = steep keratometry.
Kruskal-Wallis test.