Dude, because of eye allergies, I'd rather ride in the dead of winter than the middle of summer.

I'm not sure if this stuff will work with contacts (I wear glasses), but Visine makes an antihistamine eyedrop called Visine-A (I think it used to be called Ocuhist). Instant relief, and it lasts for hours. I put a few drops in before I ride, and carry it with me wherever I go.