Table 6.

(Online supplement): Univariate analysis for factors associated with type of astigmatism among those with astigmatism (N = 680)

		Type of astigmatism
Demographics	# of students with astigmatism	With-the-rule n (%)	Against-the-rule n (%)	Oblique n (%)	P-value
Age (years)					0.37
≤ 6	25	20 (80%)	2 (8%)	3 (12%)
7	25	22 (88%)	1 (4%)	2 (8%)
8	27	23 (85%)	0 (0%)	4 (15%)
9	30	27 (90%)	1 (3%)	2 (7%)
10	24	23 (96%)	0 (0%)	1 (4%)
11	40	32 (80%)	0 (0%)	8 (20%)
12	54	47 (87%)	0 (0%)	7 (13%)
13	56	48 (86%)	0 (0%)	8 (14%)
14	56	47 (84%)	0 (0%)	9 (16%)
15	67	57 (85%)	0 (0%)	10 (15%)
16	93	81 (87%)	1 (1%)	11 (12%)
17	76	65 (86%)	3 (3%)	9 (12%)
18	85	66 (78%)	4 (5%)	15 (18%)
≥ 19	22	17 (77%)	0 (0%)	5 (23%)
Grade					0.39
Kindergarten	29	24 (83%)	2 (7%)	3 (10%)
Grade 1	27	23 (85%)	1 (4%)	3 (11%)
Grade 2	26	22 (85%)	1 (4%)	3 (11%)
Grade 3	30	28 (93%)	0 (0%)	2 (7%)
Grade 4	28	25 (89%)	0 (0%)	3 (11%)
Grade 5	41	35 (85%)	0 (0%)	6 (15%)
Grade 6	55	45 (82%)	0 (0%)	10 (18%)
Grade 7	57	50 (88%)	0 (0%)	7 (12%)
Grade 8	58	50 (86%)	0 (0%)	8 (14%)
Grade 9	68	58 (85%)	1 (1%)	9 (13%)
Grade 10	96	83 (86%)	1 (1%)	12 (13%)
Grade 11	83	72 (86%)	1 (1%)	10 (12%)
Grade 12	82	60 (73%)	4 (5%)	18 (22%)
Gender					0.09
Male	427	371 (87%)	6 (1%)	50 (12%)
Female	253	204 (81%)	5 (2%)	44 (17%)
School location					0.34
Urban	427	356 (84%)	6 (1%)	65 (15%)
Rural	253	219 (87%)	5 (2%)	29 (11%)
Spherical equivalent of more astigmatic eye (Diopters)					0.78
≤ −6	174	145 (83%)	2 (1%)	27 (16%)
> −6, ≤ −5	75	59 (79%)	1 (1%)	15 (20%)
> −5, ≤ −4	90	74 (82%)	1 (1%)	15 (17%)
> −4, ≤ −3	84	71 (85%)	2 (2%)	11 (13%)
> −3, ≤ −2	54	46 (85%)	2 (4%)	7 (13%)
> −2, ≤ −1	67	60 (90%)	1 (2%)	6 (9%)
> − 1, ≤ −0.5	35	29 (83%)	1 (3%)	5 (14%)
> − 0.5, < 0.5	48	45 (94%)	1 (2%)	2 (4%)
≥ 0.5, < 1.0	20	16 (80%)	1 (5%)	3 (15%)
≥ 1.0	33	30 (91%)	0 (0%)	3 (9%)