look out at the majestic views of the grand canyon we assume they will always be there and for one man they won't be. And time is running out. Here's Steve osunsami with an effort to get ahead of that life-changing deadline. Reporter: 27-year-old James is going blind. Unbelievable. Reporter: He's here at the grand canyon and his seeing eye dog on a trip of the lifetime, to see as much as he can before genetic retinal disease steals his sight. You take both your hands and cup it around the sides -- Reporter: This is what he has left, like looking through a broken window at the end of a rainy hallway. Just 15% of his vision. The fact I can see this. I'll never take that for granted. Reporter: The youth that brought him here took Jonathan to see niagara falls and Devin Costello on a helicopter ride through the canyons on a sunny day. Both are already legally blind. Michael said he's teaching them to burn the images in their mind. He, too is losing his vision. I am not in denial, I have advanced glauk glaucoma. Reporter: How do you burn this in your mind? I just take it all in. Reporter: James took a number of moments, and years from now, when the last of his sight is gone, he said his imagination will bring him here. Steve osunsami, ABC news, the grand canyon.