This article is a little dated (2003) but it gives some excellent information into the "scientific" side of sunglasses and how important optics are. The test compares Oakley versus many of the top name brands out there. Great little piece of information.
https://docs.google.com/file/d/0ByldYbWwjAf4b3NpZm5IMGhTQzA/edit?usp=sharing
https://docs.google.com/file/d/0ByldYbWwjAf4b3NpZm5IMGhTQzA/edit?usp=sharing