For cycling I've recently started using Cocoons (http://www.cocoonseyewear.com/), which fit over my regular prescription glasses. These are not those huge over-glasses type, they are just barely larger than my regular glasses. My regular prescription sunglasses are too small to give me enough wind protection, especially in cooler weather, but the Cocoons fit tightly against my face and have a shelf over the lenses that seals out the wind.