Unfortunately mine are now looking like that know of any good protectant for head lights? I want to fix mine up, but I don't want to have to do it every couple of months!
if the factory UV coating is still sound, then any paint sealant or, preferably, quartz or ceramic coating will do fine, after polishing. If the the factory UV is history, then sand it well, prep and spray with 2K clear.
edit. This is for modern polycarbonate lenses, not older glass lenses.