Oakley prescription, or contacts...

Being able to see the trail is very important! Get some contacts and then buy some shades. That way you can see the next root or rock and your eyes can be protected from debri that is kicked up on the trail.

I agree, I wear contacts and use sunglasses. Make sure you bring a bottle of rewetting drops with you. I flush my eyes every once and awhile to get the dust and pollen out and it works great.

SARGE: NEVER GIVE UP, NEVER STOP TRYING!

I'm definitely voting on the the contacts over the prescription sunglasses. I had some prescription sunglasses for years (just for general use since I'm still new to mtb). They were kinda cool to have, but one thing that always bothered me about any kind of glasses instead of contacts is the peripheal vision issue. When I'm out doing something active I would much rather carry a small bottle of rewetting drops than hope my new, prescription specs don't get eaten by the spokes again. ;-)

Of course, if you can afford to shell out, I vote for laser surgery. I wasn't a candidate for LASIK because of a lack of mm of corneal tissue, so I had to get an older procedere (called surface oblation) that was extremely painful and had a very, very long recovery time. But it was still totally worth it, all around. Best part--I went with a custom cornea upgrade originally designed to reduce glare for athletes, so I have less trouble with glare on a golf ball traveling through the sunny sky, etc. It elminated all of the glare side effects you usually hear about from people who had LASIK when they complain about their vision at dawn and dusk on roads and from other headlights. The total comfort and convenience that a permanent procedure can offer you will keep you out on the trail or wherever you want to be until the rest of you is ready to come back in.

"The score never interested me, only the game." --Mae West

I use contacts, definatly take drops with you between dirt and dry eyes you cant see anything. I usually wear skydiving goggles unless its really hot. They keep alot of dirt and wind out, and wont bounce off or get ripped off your head.

As everyone else has said...I would pick contacts. Because then not only can you use them with sunglasses for biking...but you also dont have to buy more glasses for other activities such as school or work.