Toddler glasses!

So my 2 year old is blind as a bat and needs glasses. The doctor ordered them in so they should be here in about two weeks but how in the hell do you keep glasses on a two year old???? We got the rubber framed ones with the strap that keeps them on their face. Any tips? I ordered the black framed ones so that they would go with any outfit but should I have let him pick a fun color??? I may be able to call and change the frame color. How often do you need to have eye exams? Do your other kids need glasses too?