How can I check the optical drive after dropping my Mac?

I posted a question about 5 days ago...

Dropped my MacBook Pro..is it okay!?!

and one of my responses was...

The main thing I would do right now is make sure I had a good backup. You would also want to maintain a regular backup in case the hard drive should die. Check out the optical drive. You may well have been lucky and avoided serious damage so I would suggest you just continue using it and see what the future brings. Ralph

How do I go about checking the optical drive? What exactly am I suppose to look for?