Originally Posted by JohnBurke

If you're at minimums, your only concern is 'do I see the runway environment and can I descend from MDA?' If you have the approach lights, you can descend 100' below, and if you have the runway, come on down. That's not the time to be guessing what the visibility is. You needed the appropriate legal visibility to start the approach. To finish it, you need to be able to see the runway environment.