In the past few years, Franny Chapman, 18, has spent nine days whitewater rafting down the Colorado River. She’s gone indoor skydiving—twice—and traveled across the country on her own. That’s a lot for any teen. What makes these adventures even more impressive is the fact that Franny has impaired vision. Franny was born with a condition called optic nerve hypoplasia, meaning her optic nerve didn’t fully develop before she was born. She’s legally blind. But Franny prefers to say she has a visual impairment. She can make out the general shape of things. Still, she can’t see details, even with glasses. But with the help of her guide dog, Yolanda, Franny can do most things teens with full vision do. In fact, Franny thinks her disability has forced her to step outside her comfort zone. “I believe that whatever makes me or you or anyone different enlarges our world in some way,” she says. Read on to learn what it’s like growing up with impaired vision and what Franny wishes you knew about her condition.