I was cycling along a shady street at 20 mph, and didn’t see a dead tree branch sticking out at eye level until it was 2 inches from my face. By that time it was too late to avoid it, so all I could do was rely on my blink reflex. The branch scraped across my sun glasses with a snap. If I had not been wearing sunglasses, I’m pretty sure that it would have done some major damage to my face and possibly even my eye (I doubt my eyelid could have protected me). So, always wear cycling glasses!
The cycling glasses I have are Performance Brand with interchangable lenses. Something like these:
http://www.performancebike.com/shop/profile.cfm?SKU=17417
Update 6/15/06: Damn, I’m stupid. I did the same thing today! Fool me once…
Wow, good thing you had your glasses on! I need to tighten mine so they stay on my face at high speeds!