Prevalence of Corneal Astigmatism in Patients before Cataract Surgery in Northern China

Table 2

Descriptive statistics by age group.

Age group (y)	Astigmatism (D)	K1 (D) mean ± SD	K2 (D) mean ± SD	Eyes (%)
30–40	1.33 ± 0.85	42.77 ± 2.23	44.10 ± 2.38	164 (1.32)
41–50	1.10 ± 1.10	43.51 ± 1.83	44.61 ± 1.92	571 (4.59)
51–60	0.99 ± 0.71	43.91 ± 1.61	44.90 ± 1.70	1869 (15.01)
61–70	1.05 ± 0.80	44.04 ± 1.63	45.10 ± 1.70	3226 (25.91)
71–80	1.20 ± 0.83	43.95 ± 1.65	45.14 ± 1.69	4517 (36.28)
81–90	1.34 ± 0.90	43.95 ± 1.68	45.28 ± 1.70	1993 (16.01)
≥91	1.39 ± 0.82	43.73 ± 1.65	45.12 ± 1.76	109 (0.88)
𝑃^∗	<0.001	<0.001	<0.001	<0.001

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