Speaking on the Marian Finucane Show, the Louth TD said his good friend covered the cost of the operation, believed to be in the region of €30,000. Speaking of the offer, Mr Adams explained: "He said to me 'Get this done, I'll pick up the tab'." The Sinn Fein leader has been branded a hypocrite after he decided last summer to have an operation in the US rather than using the Irish public health service.
But he argued that he was not a hypocrite and instead was simply undergoing a procedure that was not available in the North.
"I have had a long-standing and very, very painful complaint. And I go back and forth to the States once or twice a year. One of my friends introduced me to his doctor who was dealing with these issues and he recommended that I should have a process of a particular kind, in fact he said it was long overdue."
The politician, who Dolours Price claimed ordered her to carry out the 1973 London bombings and also claimed ordered the abduction and murder of mother-of-10 Jean McConville, described his ailment as "very, very painful".
In relation to his eye problem, he said, "I was in constant pain. I've been in constant pain for the last maybe five years. I checked with my doctor and at that time the treatment of that kind was not available in the North," he said. "My doctor here quite rightly recommended that I get the very best treatment possible and accepted the US consultant's recommendation that it should be done with speed."
Asked how he afforded the procedure on his salary, which almost equated to the cost of the operation, Mr Adams replied: "I didn't pay for it. A very, very good friend of mine, a man called Bill Flynn, very kindly paid for it. I haven't told anybody that before.
"Myself and my wife and my family are eternally grateful for that. I'm still in recovery but I am doing very well."
Mr Flynn is a first-generation Irish-American with roots in Mayo and Down.
Mr Adams said of Mr Flynn, "He was a key figure in the Northern Ireland Peace Process, chairing the National Committee on American Foreign Policy and helping to broker the IRA ceasefire."
A chairman emeritus of Mutual of America, Mr Flynn travelled to the North to campaign for Sinn Fein to be admitted to all-party talks. He was Irish-American of the Year in 1995, and served as Grand Marshal of the St Patrick's Day Parade in 1999.