A blind boy and his mother

A young blind boy is being tucked into bed by his mother . The mom says "Now billy , pray really hard tonight and tomorrow , your wish will come true!.
Billy says , " OK mommy ". And goes to sleep . The next morning , Billy wakes up and screams " MOMMY ! Iam still blind , my wish did not come true !
The mom answerd , " I know - April Fools.