A total of 135 ( 73 female and 62 male ) Chinese-Canadian children ( aged 8-13 years ; mean [ SE ] age , 10.29 [ 0.15 ] years ; mean [ SE ] myopia , -3.08 [ 0.10 ] D ) with myopia progression of at least 0.50 D in the preceding year were randomly assigned to 1 of 3 treatments .