Polycarbonate is quite a versatile plastic. It is incredibly strong, impact resistant, and has good optical properties as well. A high index of refraction and low weight make it the ideal substance for eyeglass lenses, and its impact resistance leads to the manufacture of practically indestructable drinking glasses.

Polycarbonate eyeglass lenses can weigh less than half as much as equivalent glass lenses and are much more likely to survive a fall.

Thermoplastics rule.