I would say a lot depends on the quality of the frames. A Titanium frame should be relatively corrosion resistant. A lot of the less expensive frames are plated brass or brass-soldered, which is much more reactive.

I switched over to (extended-wear) contact lenses many years ago, but always wear plastic-framed sport glasses on the bike, for wind and debris protection. Sunglasses during the day, and light/clear shields during bad weather or at night.

Plastic or metal, it wouldn't hurt to give them a good soap-and-water rinse, then blow dry on a regular basis, to eliminate the salts, oils and other stuff that builds up over time.