Prime among these is the full cutoff fixture . If properly installed, this unique fixture puts ALL of its light below the horizontal and NONE goes directly from the fixture into the sky. This has 2 benefits. Compared to the older designs, full cutoffs can have a lower wattage since the light that was once being wasted is now being directed onto the ground, thus you can have a lower wattage bulb to achieve the same lighting levels as was obtained with the older fixture. Glare is dramatically reduced.
Glare is never good.
It reduces visiblity for the same reason that you put your visor down when driving in the direction of a low Sun. There is a large difference in brightness present. This causes your iris to contract and causes light scatter in your eye. The secret to good lighting is to illuminate your subject without blinding the observer with glare. How many traffic accidents could have been prevented if we would only use fixtures that don't blind the driver with glare.