Josh Taylor won Saturday's epic super-lightweight encounter with Regis Prograis despite being "blind for about three rounds".
A series of head clashes and nine rounds of ferocious boxing left the Scottish fighter's right eye closed.
"Tactics went out of the window because I was blind for about three rounds," he said after winning a majority decision.
"I couldn't see anything from this side. I was fighting on instinct and just heart and determination."
Pointing to his disfigured eye, the 28-year-old from Prestonpans told BBC Scotland: "My personal situation was what was driving me on. There was no way I was losing, no way."
Taylor's training camp for the 10st unification bout between two previously undefeated world champions had been disrupted by the death of his girlfriend's father and by the loss to cancer of his trainer Shane McGuigan's sister, Danika.
"I've visualised it and wanted it so much, doing it is such a huge relief," said the southpaw, who in 16 professional fights has now won two world titles as well as the Ring Magazine belt, awarded to the best boxer in the division.
"With my girlfriend losing her dad, James Murphy, that was what was driving me on the last couple of rounds. It was some fight, a war.
"It was just in my mind, 'I've got to win this for Jimmy', and when my hand got raised the roof came crumbling down."
Houston-based Prograis was boxing outside the United States for the first time after 24 wins but had spent at least three weeks in London preparing for his toughest bout to date.
The 30-year-old was gracious in defeat, telling Sky Sports: "It was a close fight. The better man won tonight and that was cool." Taylor described him as a "worthy champion" for whom he had "nothing but respect".
Taylor felt he had won the fight by perhaps two rounds, while BBC Radio 5 live's commentary team of Mike Costello and Steve Bunce had it at six rounds apiece as they awaited the judges' verdict, which was 114-114, 115-113, 117-112 in favour of The Tartan Tornado.
"There was a bit of everything in that fight," said Taylor in his changing room.
"I boxed on the back foot, I boxed on the front foot. I went in to the trenches with him and had a fight with him and beat him on that as well. He has very good head movement, very good timing and quite heavy hands as well.
"I thought I won by a couple of rounds but the judges are at different angles ringside so you never know what they are seeing and what they are scoring."
'I believe I can beat anyone'
Clutching the iconic Ring Magazine belt, Taylor, who added the WBA and World Boxing Super Series titles to his IBF crown, indicated he would happily take his next fight to America, where he could attempt to wrest the WBC and WBO belts from California's Jose Ramirez.
"I'm open to anything," said Taylor. "Without sounding big headed or arrogant, I really do believe I can beat anyone.
"All fighters dream of fighting in Las Vegas, MGM Grand, your name up in big lights, or Madison Square Garden.
"But another iconic one would be Edinburgh Castle in the middle of the summer, midnight with the castle lit up in the background, or at Easter Road, the Hibs ground.
"It would be amazing, a big unification fight. Scotland would never have seen anything like that."