In "Can´t see"... Is short for "can not" , so in more formal context it wouldn´t be used.
Other than that, "cannot" is a (more) formal way to me, and "can´t" would be understood by people of both sides of the pond.
In the Book - the scriptures - you will see "cannot" but you will see "can´t" in the contemporary versions.
You shouldn´t use one way and the other in the same writing, though. If you use one way, you stick to it.