Table 4. Mean Cylinder Power and Prevalence of Astigmatism in the Worse Eye Determined by Autorefraction.

Age(yrs)	N	MeanCylinder(D)	SD	Prevalence of astigmatism (Cylinder ≤−1.5 D in the worse eye)
				N; %; 95%CI	With-the-rule	Against-the-rule	Oblique
					N; %; 95%CI	N; %; 95%CI	N; %; 95%CI
All	2478	−0.47	0.52	202; 8.2%; [7.07%–9.23%]	176; 87.1%; [82.51%–91.75%]	5; 2.5%; [0.33%–4.62%]	21; 10.4%; [6.19%–14.61%]
3	373	−0.53	0.55	38; 10.2%; [7.12% –13.26%]	32; 84.2%; [72.62%–95.80%]	1; 2.6%; [0.00%–7.72%]	5; 13.2%;[2.41%–23.91%]
4	817	−0.49	0.54	76; 9.3%; [7.31%–11.29%]	67; 88.2%; [80.89%–95.42%]	4; 5.3%; [0.24%–10.28%]	5; 6.6%; [1.01%–12.15%]
5	846	−0.46	0.51	58; 6.9%; [5.15%–8.56%]	48; 82.8%; [73.04%–92.48%]	0; 0.0%; [0.00%–0.00%]	10; 17.2%; [7.52%–26.96%]
6	442	−0.43	0.50	30; 6.8%; [4.44%–9.13%]	29; 96.7%; [90.24%–100.00%]	0; 0.0%; [0.00%–0.00%]	1; 3.3%; [0.00%–9.76%]
P trend		0.05		0.09
Boys	1309	−0.47	0.53	109; 8.3%; [6.83%–9.82%]	94; 86.2%; [79.77%–92.71%]	3; 2.8%; [0.00%–5.82%]	12; 11.0%; [5.13%–16.89%]
3	201	−0.56	0.59	23; 11.1%; [7.04%–15.84%]	17; 73.9%; [55.97%–91.86%];	1; 4.3%; [0.00%–12.68%]	5; 21.7%; [4.88%–38.60%]
4	433	−0.47	0.50	37; 8.5%; [5.91%–11.18%]	33; 89.2%; [79.18%–99.19%]	2; 5.4%; [0.00%–12.69%]	2; 5.4%; [0.00%–12.69%]
5	437	−0.44	0.55	28; 6.4%; [4.11%–8.70%]	24; 85.7%; [72.75%–98.68%]	0; 0.0%; [0.00%–0.00%]	4; 14.3%; [1.32%–27.25%]
6	238	−0.45	0.49	21; 8.8%; [5.22%–12.43%]	20; 95.2%; [86.13%–100.00%]	0; 0.0%; [0.00%–0.00%]	1; 4.8%; [0.00%–13.87%]
P trend		0.06		0.19
Girls	1169	−0.48	0.52	93; 8.0%; [6.40%–9.51%]	82; 88.2%; [81.61%–94.74%]	2; 2.2%; [0.00%–5.10%]	9; 9.7%; [3.67%–15.69%]
3	172	−0.48	0.49	15; 8.7%; [4.50%–12.94%]	15; 100.0%; [100.00%–100.00%]	0; 0.0%; [0.00%–0.00%]	0; 0.0%; [0.00%–0.00%]
4	384	−0.51	0.58	39; 10.2%; [7.13%–13.18%]	34; 87.2%; [76.69%–97.67%]	2; 5.1%; [0.00%–12.05%]	3; 7.7%; [0.00%–16.06%]
5	409	−0.48	0.52	30; 7.3%; [4.81%–9.86%]	24; 80.0%; [65.69%–94.31%]	0; 0.0%; [0.00%–0.00%]	6; 20.0%; [5.69%–34.31%]
6	204	−0.41	0.44	9; 4.4%; [1.59%–7.23%]	9; 100.0%; [100.00%–100.00%]	0; 0.0%; [0.00%–0.00%]	0; 0.0%; [0.00%–0.00%]
P trend		0.24		0.09