No one knew a Naperville teen couldn't see until he was 15. His mom's new book explains why.

Sebastian Duesing is an art student who can't see - at least not in the typical way.

His blindness wasn't discovered until three years ago, when he was 15 and his family noticed he couldn't recognize himself or relatives in pictures.

"Eyeless Mind: A Memoir About Seeing and Being Seen" is his mother's effort to spread awareness about the reason for his blindness and the damage caused by the fact the condition often goes unnoticed. The book comes out April 19.

Author Stephanie Duesing of Naperville said her son could navigate Waubonsie Valley High School in Aurora without bumping into things or people, compete in diving and water polo without raising any red flags, and make paintings and sculptures with photorealistic precision. But he couldn't see?

This sparked concern his parents had never felt about Sebastian, a straight-A student whose intellectual gifts were so strong he qualified to be promoted a grade above his age while he was in elementary school, so strong he scored a perfect 150 on the verbal portion of the IQ test.

"No one ever suggested to us there was anything wrong with Sebastian," his mother said. "We have photos of him making eye contact. He appears to be typically sighted."

In the book, with a cover graced by a self-portrait Sebastian painted, are explanations of the ways the teen made it through 15 years without being able to see - and without anyone knowing it.

Sebastian's strong verbal abilities to perceive and recall letters helped him give words to the things around him, and therefore to "see" them, his mother said. As a toddler, he started counting the steps and turns in his house so he could get around. He did that at each new school.

"Everything in my experience of everything is words," Sebastian said. "I see with words. I'm a very verbal person."

Sebastian now uses Google Maps on his phone to navigate Chicago, where he had been living on campus of the School of the Art Institute of Chicago until the new coronavirus outbreak began. He can't drive, but he uses public transportation.

"Everywhere he goes, nothing ever looks familiar to him," his mother said.

Duesing, an early childhood music and movement specialist, credits some of Sebastian's ability to navigate without sight to his early exposure to music, movement and art. She said she sang to him, bounced him and danced with him since his earliest days.

"Sebastian has always been a maker. He quite literally taught himself to see with art when he was little," Duesing said. "He's the only person in the world known to process his vision verbally. He quite literally sees with words."

Sebastian's mother said the family endured expensive and traumatizing medical visits across the country and the world en route to learning the cause of Sebastian's blindness. Expensive because the Duesings racked up $150,000 in medical bills, traumatizing because of the lack of belief they encountered.

"We were labeled crazy by the medical establishment," Duesing said.

At the end of the process, a medical scan showed Sebastian has "massive brain damage" from his birth, when he suffered a stroke in utero and his mother had a stroke as well, nearly causing her death.

Sebastian was diagnosed with cerebral/cortical visual impairment, which his mother said is not recognized within the medical community by a "diagnostic code."

Abbreviated as CVI, the condition involves a malfunction of the brain's visual pathways, so the eyes function normally but the neurological skill of vision does not.

CVI is the top cause of visual impairment in children in the developed world, according to a 2017 paper in the journal Seminars in Pediatric Neurology. But Sebastian said he's seen so many doctors the number is "in the triple digits," and almost none of them knew the condition existed.

That's why the book went from a few chapters Duesing wrote in 2018 to a 305-page memoir she completed last year. Her son feels grateful she stepped up to speak about the challenges encountered by those whose blindness isn't easy to identify.

"It's a tremendously important and meaningful work," he said. "It has a lot of power to do good."

The ways he copes with CVI are a tired topic for Sebastian, not something he likes to discuss. So he's letting his mother's book do the talking.

"I want more awareness to translate into better identification and then better support for everyone who has (CVI)," he said.

The duo had hoped for an April release party at hometown book seller Anderson's Bookshop, but the event has been postponed because of concern about COVID-19.