The prime minister has spoken exclusively to BBC Scotland about the future of the NHS and the pioneering eye surgery that saved his sight.
Gordon Brown was speaking in an interview in the run-up to the 60th anniversary of the NHS.
He said he had never expected the surgery he had in Edinburgh to last so long.
He added that state-funded healthcare will become more important in the future.
When Gordon Brown was a student in Edinburgh, he was kicked in the head during a rugby scrum.
He suffered a detached retina, which left him blind in one eye. Not long afterwards he was admitted to Edinburgh Royal Infirmary with vision problems in the other eye.
Prime Minister Gordon Brown remembers trolleys serving Guinness being wheeled around wards
Speaking to the BBC he said he was "lucky" because his operation had been done by a highly-trained surgeon, the day before the doctor went on holiday.
Otherwise, the prime minister said his condition would have deteriorated while he waited.
He added: "It turned out to be very successful and it's held for all these years.
"If somebody had said to me having lost the sight in one eye you would have one operation that would last for effectively 35 years and everything would be OK after 35 years - I wouldn't have bet on that."
Mr Brown said that publicly-funded healthcare will become more relevant in the future as genetic advances show which people are more likely to suffer ill health, and therefore make them uninsurable.
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