I also wear gas perm lenses, and I pretty much can't ride without glasses. I have variously 1. suffered with dark lenses when it gets dark; 2. carried an extra pair; 3. bought glasses with interchangeable lenses. The third option is what I do now. I put the extra lenses in their cloth case in my jersey pocket & plan a place to switch them out.

My eyes are really sensitive to light, so I'm leery of the photosensitive lenses. Tried them many years ago and they never got nearly dark enough outside and stayed a bit too dark inside. The worst of both worlds. I'd think they'd have improved since then, though.