If allowed to follow close enough we have the seeing eye human with the dog following the shadow motion in front of it. My mom had a dog with severe cataracts that would follow her closely.

In the did you know category... A dog does have some sensory capabilities thru its whiskers per finding its way around. The whiskers of Cats are more acute sensory organs in this regard.

Note: High doses of Prednisone for a long period of administration can contribute to the development of cataracts.