Table 1.

The Distribution of Spherical Equivalent Among Different Birth Month Blocks in Grade 1 and Grade 2 at 2018 Visit

	Grade 1				Grade 2
	May to Aug 2012	Jan to Apr 2012	Sep to Dec 2011		May to Aug 2011	Jan to Apr 2011	Sep to Dec 2010
	Block Youngest	Block Middle	Block Oldest	P	Block Youngest	Block Middle	Block Oldest	P
Sample size	573	460	432	—	424	432	525	—
Gender				0.017*				0.687*
Male	330	224	230		225	232	268
Female	243	236	202		199	200	257
Mean age	6.42 ± 0.11	6.75 ± 0.11	7.07 ± 0.11	<0.001†	7.42 ± 0.11	7.76 ± 0.11	8.08 ± 0.11	<0.001†
SE	1.12 ± 0.61	1.10 ± 0.57	1.05 ± 0.55	0.149†	0.82 ± 0.69	0.82 ± 0.69	0.86 ± 0.71	0.554†

^*χ² was used.

^†One way analysis of variance was used.