[ Other - General Health Care ] Open Question : is this a normal age?

okay so last year i was 12 turning 13 when i went to the eye doctor and i got tested for being nearsighted. haah well i have terrible vision, and i'm not exaggerating. but the weird thing is i have never had any problems previously and was just wondering why these eyesight problems came on when i was about 13 and not like 4. haha kinda random but just wondering