How to know which fields were updated

I'm working in laravel 5, I have a module where the user can update the information of students, for that The user has a preloaded form with the current data and he can modify the fields that he wants.Then, in the controller I do:

$perfil->update(Input::all())

That works pretty good. So my question is: there's a way of get the name of the fields that have been updated?

via Chebli Mohamed