Find them on Google, (enter 'night driving glasses'), from a couple of quid upwards.
The theory is that your eyes recover more quickly from glare in the orange/yellow section of the spectrum. It's why many years ago the French specified yellow for car headlights, and was one of the advantages stated when orange street lights were introduced.
orange street lights are ridicolous, the theory itself states why really if we recover more quikly from orange light it is probably because we can't see as much orange light as white or green, so obviously you can't see sod all in orange light I just drive around built up areas with my full beam on fearing some idiot wearing black (like everybody seems to so nowadays) is going to appear from no where the other problem is due to an attempt to economise the poles are 3-6 feet shorter than they should be so you have the lights "in your face" especially driving down hill and so get glared anyhow, but hey its the theory less light to see by easier to recover from