1. They'd need to fit over a largish pair of prescription glasses--requiring a bridge rather than separate lenses.
2. They ought not to look too brazenly modern; since my particular flavor of steam carries a strong whiff of diesel, matte plastic in a subdued color (which could be construed as gutta-percha or Bakelite) would be just fine.
3. It would be even better for them not to be ruinously expensive.
(These welding goggles fulfill conditions #1, #2, and probably #3, but I've discovered welding goggles to be too dang dark for casual wear in non-welding situations; these two styles from Harbor Freight, worn in blazing noonday summer daylight, enabled me to discern the approach of a bus but not to read the destination display on its sign.)