Group: A (n: 300)

Group: B (n: 300)

Number of workers

Number of workers with RE

Number of workers

Number of workers with RE

≤2-yr

27 (9%)

10 (3.33%)

25(8.33%)

5 (1.67%)

The chi-square statistic is 44.9775. The p-value is <0.00001. Significant at p < 0.05.

RE: Refractive error

3-yr

36 (12%)

14 (4.67%)

31(10.33%)

6 (2%)

4-yr

47 (15.67%)

20 (6.67%)

52 (17.33%)

11(3.67)

5-yr

48 (16%)

25 (8.33%)

45 (15%)

12 (4%)

6-yr

37 (12.33%)

22 (7.33%)

41(13.67%)

12 (4%)

7-yr

35 (11.67%)

21 (7%)

30 (10%)

9 (3%)

8-yr

23 (7.67%)

14 (4.67%)

27 (9%)

8 (2.67)

9-yr

22 (7.33%)

13 (4.33%)

30 (10%)

6 (2%)

>10-yr

25 (8.33%)

17 (5.67%)

19 6.33%)

7 (2.33%)

Total

300 (100%)

156 (52%)

300 (100%)

76 (28.34)