I always ride with lights in the rain, even if it's a "bright" rain. I also wear sunglasses to keep the rain out of my eyes. If you have lighter or clear lenses, try those. In a pinch, anything but superdark ones will work. There is some visibility loss, but for me at least, I lose less from the darker lenses than I would from trying to squint rain out of my eyes all the time. (Yes, I have a visor or cap brim).
I love riding in the rain as long as I know I can get dry afterwards. I just tell myself I'm only as wet as in the pool, and then it's fun. Also, once you accept the wetness you don't have to worry about cars splashing you anymore!