Former England striker Michael Owen says he would "swap eyes" with his son if it was possible to help the teenager see again.
James Owen, 17, who hoped to follow in his father's footsteps, was diagnosed with Stargardt disease, a degenerative eye condition, when he was eight.
Speaking on the BBC Access All podcast, Michael said: "If I could give him my eyes ... I would.
"I would pay every cent I've got to make James see again."
James is from a family of top footballers. Michael played as striker for clubs including Liverpool and Real Madrid, and somewhat controversially went on to play for Liverpool's big north-west rivals Manchester United. His father Terry Owen started his own footballing career at Everton in 1966.
The beautiful game was very much in James's blood, but it slowly dawned on the Owens something unusual was going on with their young son.
James was a good player when he was on the ball, but he often failed to track passes or notice player movements further down the field.
It became more concerning when he struggled to compete on bigger pitches and it was all getting too fast-paced, James admits.
At home or on holiday, Michael says he often got frustrated when trying to take family photographs as his young son always seemed to look to the side of the camera rather than at it.
Even so, Michael says it came as a "hammer blow" when he and wife Louise were referred to an eye specialist and were informed of James's diagnosis.
James told Access All presenter Emma Tracey, who herself has no sight, that his "central vision is blurry" and that "I struggle with seeing different colours and different lights" although he has "good peripheral vision".
Listen to the Access All podcast with Michael and James Owen, and spot the moment when the tables turn and Michael starts to interview Access All's blind presenter , Emma Tracey, about her experiences...
According to the RNIB, Stargardt disease is an inherited eye condition that affects the macula, the central part of the retina, and causes a reduction in vision there.
Understandably, Michael says it left him with parental guilt.
"As a parent you just want everything to be perfect - and he is - but of course it was a sad time," he says.
"Thinking about the future - will he be able to drive? Will he be able to work? All these things run through your mind."
He says the procedures and tests which followed over the years while medical staff monitored James's condition were also hard to watch.
"You're pushing your son forward to get something you know is going to be painful," he says. "It's just horrible to see. You want to take all the pain away."
James has learned to navigate the world around him by using tricks that other visually impaired people will know well.
"I'll notice what colour my dad's jumper is. So if I ever go out, then I would be able to recognise him from the colour, not from his face because I struggle with detail."
Michael, who now focuses on training racehorses, says "time is a great healer" and while James had found it difficult to comprehend the diagnosis when he was younger, he has since become very positive about it.
"He's just mentally very, very strong. He's got a great mindset," Michael says. "I've got four children and I'm probably the least worried about James's future."
The father and son are about to release their first documentary - Football is for Everyone - exploring James's sight loss and an adapted version of football called futsal.
The duo follow the visually impaired futsal England squad as they compete in the 2023 visually impaired world cup hosted in Birmingham.
The game is played on a smaller, indoor, pitch with a heavier ball that doesn't bounce as much. Players are classified by their visual impairments and only so many players of the same classification can play at once. The goalkeepers are fully sighted but are confined to the goal.
When he joined a training session, James quickly got to grips with the game.
"I did actually score at some point while training with the England team which I'm quite happy about," he says.
Then he pauses, and confesses. "I actually got megged and then scored an own goal. It was not a great moment."
Michael can't help but jokingly stick the knife in: "It's one of the most embarrassing things in football, if you get nutmegged."
Nutmegging, for the uninitiated, is when one player kicks the ball through another player's legs. Adding an own goal into the mix, just increases the humiliation.
"It's just been a surreal experience," James says of making the documentary which started before the pandemic. "I used to be quite shy as a kid, but it's definitely brought me out my shell."
Although he has sidelined football, James says "I've got a lot of dreams".
He has found a passion for business, which he is studying at college and hopes to own his own business in the future, although he says he is keeping his options open about what that might be.
Michael has a hunch. "When I retire from work in 30 years or something, he'll probably take over the 'family empire'," he laughs.
James and Michael's documentary, Football Is For Everyone is available from 30 January on TNT Sports and Discovery Plus.
From BBC