Change table_name and field to match your table name and field in question:
Code:
UPDATE table_name SET field = REPLACE(field, 'children eyeglasses', 'kids glasses') WHERE INSTR(field, 'children eyeglasses') > 0;
INSTR (ori_str, sub_str):
ori_str The string to be searched.
sub_str The string to be searched for within the ori_str
MySQL INSTR() takes a string and a substring of it as arguments, and returns an integer which indicates the position of the first occurrence of the substring within the string.