CHICAGO (CBS) The Chicago Marathon is coming up this Sunday. And while marathon runners often have partners to help them keep pace during the race, one Chicago runner relies on his.

Training 10 months for a marathon on a treadmill sounds boring and confining, but for E.J. Scott, it’s the easiest option. He has Choroideremia and is legally blind.

“Choroideremia is a degenerative, hereditary eye disease that attacks peripherally and erodes it until total blindness,” Scott told CBS 2’s Megan Mawicke. “There is not a treatment or a cure right now.”

One in 50,000 people have Choroideremia. E.J.’s brother and nephew also have it. He was diagnosed seven years ago when he was 28. He now has less than 20 percent of vision in each eye.

“It kind of explained a lot of things, like bumping into things,” Scott says. “Once I got over the denial part of it, I realized that my eyes are getting worse. Then it got really scary.”

E.J., a self proclaimed non-runner, took up running to bring awareness to the disease. He will do the marathon with a guide. Because he is extremely sensitive to sunlight, which progresses the disease, he’ll have to wear a blindfold.

“If I didn’t have it, I get really bad headaches and it would sting and burn and be a big mess,” he says.

Scott understands the difficulty of running this way. He said it can be stressful, especially if his guide abruptly stops or says “watch out.”

“I just hope I don’t bump into anybody, which I have (done) – I do bump into people,” Scott says. “I almost try to zone out and just to distract myself and think about other things.”

The finish line is just the first step for him. He said hopefully he can also educate people.

“Blind people fly so under the radar — especially people with Choroideremia,” he said.

For more information on Choroideremia, go to choroideremia.org, or go to E.J.’s Facebook page. There is a link there to make donations to help fight Choroideremia.