If you can't see, you are not going anywhere. So, throw away your broken, scratched or worn out helmet shield and swap it for one of these brand new Simpson replacement shields.
Note: Shields fit specified Simpson helmets only.

Simpson Micro Fiber Dual Shield Storage Bag
This dual shield storage bag is excellent for keeping your helmet lenses scratch-free and clean when you are not using them. Designed to hold two shields in separate compartments. Made from a durable micro fiber that can be machine washed. Storage Bag also doubles as an excellent "scratch-free" cleaning cloth.