Been a while since I have posted here but here goes. I have been using prescription sun glasses for the last two years and have been dreading the idea of having to pay for new ones if my prescription changes. I thought I would give these shields a try and believe it or not it was a good idea, for me anyway.
All-Weather Bike Helmet Shield, Bicycle Helmet Visor :: Wide Eyez
I bought the two part kit with both dark and clear shields and to tell the truth I find it better almost all the way around. The big plus is they don't fog up in the cold.