I'd plan a vet exam for your dog.
It could be the gray coloration is due to cataracts but it may also be due to lenticular or nuclear schlerosis which is an aging of the lenses causing them to become grayish in color. With this condition, the lens of the eye appears cloudy, but the dog can usually see quite well unlike when the vision is blocked by cataracts.
http://www.peteducation.com/article.cfm?c=2+1606&aid=407
Sometimes retinal degeneration is happening at the same time as the eye is getting cloudy and that will impact vision. An in person exam of the eyes by a vet would get you the most info on what is going on.
More on cataracts here
http://www.animaleyecare.net/diseases/cataract.htm
You might ask your vet about using Ocluvet eye drops
http://www.ocluvet.com/
depending on what the exam finds.
Hope this helps you!
Dog Expert:Rescue, Train,Breed,Care
30+ yrs dog home vet care & nursing, rescue, behavior&training, responsible show breeding, genetics
You are very welcome - I hope all turns out well!
Thanks for the above accept!