Photochromatic face shields?

I am a Store Manager at a local Optical shop, and sell a lot of Transitions prescription eyewear.  I was wondering if anyone knows if this sort of technology is available in face shields of motorcycle helmets.
For those of you that don't know, photochromic eyewear such as Transitions uses a UV activated dye to darken in direct sunlight, then goes back to clear again in the absence of sunlight.  This would be awesome for motorcycle helmets, because it means that you would not have to carry around an extra face shield.  It would darken automatically for daytime use, then go clear when you are riding at night.  How dark it gets it directly related to the intensity of sunlight (UV rays).
I would pay good money for this sort of convenience, so I'm sure somebody has thought of it. Anybody know if this is available? 

i havent seen anything like it but that sounds awesome, keep us informed if you fiind anything i might look into it.
 
chace
 

Yes there is something like that, I believe it's fairly new too

https://www.motoliberty.com/prod_detail.asp?Prod_ID=370

This is for a scorpion helmet but I'm sure other companies won't be far behind with this.  Also, search around for your helmet type, it might already be out there. 

"DucRacer" from the cbrworld.net forum is involved with a company that sells them .. relatively new:
Helmet with Photochromatic Visor

(actually, I should say "will be" selling them very soon but the sites up and running. the helmets have some unique nifty features in addition to the pc visor)

Its available ..I have a photochromatic shield on my scorpion..

It goes to a light smoked look during the day.Really helps a lot on bright days.TO me its  agreat thing to have because when i leave for work the sun is coming up and when i get home its dark..Beats having to carry two shields.

You guys might want to check this site out.  www.akumahelmets.com  The selection is not all that but the ones they do have are pretty good. 

Too bad these don't fit Shoei or Arai.

In the British Isles we've had a product called "Hyper-Optik" which is a visor insert like an anti fog insert that really works a treat. I have used them for about 3 years or more whilst racing when the weather is suspect or when I'm riding a late session in practice in the Manx Grand Prix or Endurance event. No only did it react good when the light was bright, but when the light faded it went to a light enhancing yellow tint that helped pick out the dry lines when it rained. It also helped prevent he visor fogging up when it went cold.

Wow. These are freaking sweet.

Now only if I could get an affordable prescription visor so I wouldn't have to wear contacts/glasses.