I bought a pair of prescription Seaspecs sunglasses.  They are designed for aquatic sports, are secured by a strap instead of arms and are anti-fog.  I bought them for fishing but also used for mountain biking and other outdoor activities.


From memory $200US and available tinted (polarised) or clear.


If you want to see some in the flesh Gill do a re-badge of Seaspecs (non-prescription) which Burnsco and presumably other boating supply stores stock.