Couple of hints for better night riding. I have very bad standard vision, 20/450, and astigmatism (egg-shaped or irregular shaped eye) also. Here is what has helped me.
A. Go get your vision checked. There are two issues with night vision, one being "starring"; an indication of astigmatism. The other is poor rod and cone production (dim night vision). Astigmatism can be corrected with the proper lenses, and the new plastics and compund lenses are startlingly clear; dim night vision can usually be alleviated with supplements high in Vitamin K and a few others.
B. Use no tint at all on your visor. I have switched to the HJC Sy-MaxII
http://www.hjchelmets.com/ with the integral tinted retractable shield; it stays clean,. is there when I need it, and goes away with a touch when I don't. A number of manufacturers make helmets with them.
C. I keep plastic cleaner and a soft cloth in my kit bag...dirty shields lose much light transmission. I also keep Aquapel or RainX for Plastic (don't use the formula for glass, as it will cloud your shield) because it keeps the shield cleaner and the drops are smaller and they stream right off in everything but the heaviest downpour.
D. I have a two strips width of black electricians tape across the top of my shield; they serve two purposes:
When driving into the sun in the morning or dusk, by dipping my chin I can block out the direct sunlight and still see traffic.
After dark if I am driving into some dork's brights, the same applys; tilt my head down and to the side as the idiot passes and I get to keep a modicum of my night vision. Costs about a penny and it works.
When riding at night, don't smoke; nicotine destroys the rods and cones needed for night vision.
Happy riding.