Asthenopia in schoolchildren

Figures & data

Table 1 Sample description by demographic, economic and behavioural variables, ophthalmic examinations and self-reported symptoms. Asthenopia in schoolchildren in Pelotas according to the following independent variables: crude prevalence and association. Pelotas, Rio Grande do Sul, Brazil, 2012 (n=964)

Variable	N (%)	Prevalence % (95% CI)	Prevalence ratio (95% CI)	P-value
Age (years)				0.001a
6–9	361 (37.5)	18.6 (14.5–22.6)	1
10–14	536 (55.6)	28.0 (24.2–31.8)	1.51 (1.17–1.95)
15–16	67 (6.9)	31.3 (19.9–42.7)	1.69 (1.11–2.56)
Sex				0.40b
Male	532 (55.2)	23.7 (20.1–27.3)	1
Female	432 (44.8)	25.9 (21.8–30.1)	1.09 (0.88–1.37)
Maternal schooling (years)				0.4a
0–3	81 (8.5)	29.6 (19.5–39.8)	1
4–7	340 (35.8)	21.2 (16.8–25.6)	0.71 (0.48–1.06)
8–10	242 (25.5)	24.8 (19.3–30.3)	0.84 (0.56–1.25)
11 or more	287(30.2)	27.5 (22.3–32.7)	0.93 (0.63–1.36)
Economic status*				0.54a
AB	343 (36.2)	23.3 (18.8–27.8)	1
C	551 (58.1)	25.8 (22.1–29.4)	1.10 (0.87–1.40)
DE	54 (5.7)	24.1 (12.3–35.9)	1.03 (0.62–1.72)
Race				0.69b
White	760 (78.8)	25.0 (21.9–28.1)	1
Non-white	204 (21.2)	23.5 (17.7–29.4)	0.94 (0.71–1.24)
Wears glasses				0.004b
No	891 (92.8)	23.5 (20.7–26.2)	1
Yes	69 (7.2)	37.7 (26.0–49.4)	1.61 (1.16–2.22)
Prior ophthalmological examination				0.2b
No	657 (68.2)	23.3 (20.0–26.5)	1
Yes	306 (31.8)	27.4 (22.1–32.5)	1.18 (0.94–1.48)
Internet/computer at home				0.40b
No	352 (36.6)	23.3 (18.9–27.7)	1
Yes	611 (63.4)	25.4 (21.9–28.8)	1.09 (0.86–1.38)
Video game at home				0.62b
No	221 (23)	25.8 (20.0–31.6)	1
Yes	742 (77)	24.3 (21.2–27.4)	0.94 (0.73–1.22)
Acuity 0.8 or greater				0.58b
Absent	69 (7.2)	21.7 (11.8–31.7)	1
Present	895 (92.8)	24.5 (21.7–27.4)	1.13 (0.71–1.79)
Stereopsis				0.81b
Absent	5 (0.6)	20.0 (−36.0–75.5)	1
Normal	824 (99.4)	24.4 (21.5–27.3)	1.22 (0.21–7.08)
Strabismus				0.78b
No	858 (96.5)	24.6 (21.7–27.5)	1
Yes	31 (3.5)	22.6 (7.0–38.2)	0.92 (0.47–1.78)
Vertical heterophoria				0.74b
No	814 (98.8)	24.5 (21.5–27.4)	1
Yes	10 (1.2)	20.0 (−10.0–50.1)	0.82 (0.24–2.84)
Near horizontal heterophoria				0.7b
No	320 (39.1)	23.8 (19.1–28.4)	1
Yes	499 (60.9)	25.0 (21.2–28.9)	1.05 (0.82–1.35)
Far horizontal heterophoria				0.23b
No	320 (39.1)	25.6 (21.9–29.2)	1
Yes	499 (60.9)	22.4 (17.4–27.3)	0.88 (0.67–1.14)
Spherical ametropia				0.90a
Emmetropic	84 (8.7)	31.0 (20.9–41.0)	1
Mild hyperopia (>+0.50D <+1.99D)	688 (71.6)	23.4 (20.2–26.6)	0.76 (0.53–1.07)
Moderate hyperopia (>+2.0D)	131 (13.6)	26.7 (19.0–34.4)	0.86 (0.56–1.32)
Myopia (>−0.50D)	58 (6.1)	25.9 (14.2–37.5)	0.84 (0.49–1.43)
Astigmatism				0.30a
No	598 (62.2)	23.6 (20.2–27.0)	1
>0.75D <2.0D	306 (31.8)	26.5 (21.5–31.4)	1.12 (0.89–1.42)
>2.0D	57 (6)	26.3 (14.5–38.1)	1.12 (0.71–1.76)
NPC				0.09b
<6 cm	479 (50.1)	26.9 (22.9–30.9)	1
≥6 cm	478 (49.9)	22.1 (18.4–25.9)	0.82 (0.65–1.02)
AC/A ratio#				0.57b
Abnormal	163 (17.1)	26.4 (19.5–33.2)	1
Normal	788 (82.9)	24.1 (21.1–27.1)	0.91 (0.69–1.22)
Refractive status**				0.02a
A	678 (74.3)	22.9 (19.7–26.0)	1
B	126 (13.8)	25.4 (17.7–33.1)	1.11 (0.80–1.54)
C	39 (4.3)	20.5 (7.3–33.8)	0.90 (0.48–1.69)
D	69 (7.6)	37.7 (26.0–40.4)	1.65 (1.18–2.30)
Time to go to bed				0.50b
Regular	670 (69.6)	27.4 (23.5–31.3)	1
Irregular	293 (30.4)	21.5 (17.8–25.3)	0.92 (0.72–1.18)
Asthenopia
No	726 (75.3)
Yes	238 (24.7)
Burning eyes				<0.001
No	726 (75.3)	12.9 (10.5–15.4)	1
Yes	238 (24.7)	60.5 (54.2–66.8)	4.67 (3.77–5.79)
Eye ache				<0.001b
No	705 (73.3)	10.6 (8.4–12.9)	1
Yes	257 (26.7)	63.0 (57.1–69.0)	5.93 (4.69–7.48)
Itching eyes				<0.001b
No	583 (60.5)	11.5 (8.9–14.1)	1
Yes	380 (39.5)	44.7 (39.7–49.8)	3.89 (3.03–5.01)

Notes:

a Wald’s linear trend test.

b Wald’s heterogeneity test.

* Economic status: (AB) high; (C) medium, (DE) low.

** Refractive status: (A) mild hyperopia, mild simple astigmatism, does not wear glasses; (B) moderate hyperopia, moderate astigmatism, does not wear glasses; (C) myopia, does not wear glasses, (D) wears glasses.

# AC/A ratio: relationship between accommodation and convergence.

Abbreviations: CI, confidence interval; NPC, near point of convergence; D, diopters.

Table 2 Asthenopia-associated factors following adjusted analysis. Pelotas, Rio Grande do Sul, Brazil, 2012 (n=964)

Variable	PR (95% CI)	P-value
First level
Age (years)		0.001a
6–9	1
10–14	1.55 (1.19–2.01)
15–16	1.69 (1.20–2.70)
Second level
Wears glasses		0.018b
No	1
Yes	1.60 (1.16–2.20)
NPC		0.08b
<6 cm	1
≥6 cm	0.73 (0.49–1.07)

Notes:

a Wald’s linear trend test.

b Wald’s heterogeneity test.

Abbreviations: CI, confidence interval; NPC, near point of convergence; PR, prevalence ratio.

Figure S1 Questionnaire about visual complaints in children (yes/no/sometimes).