Nick Hewer was an "inch away" from having a stroke.
The \'Countdown\' host says he is lucky to be alive after the health scare, which happened when he was doing charity work in Africa.
Nick told the Daily Express newspaper: "I had the scare when I was in Sierra Leone while I was working for the charity Street Child.
"I was in my hotel room squinting away at my laptop when my vision went all funny. Unbeknown to me, a blood vessel behind my retina had burst."
The 75-year-old TV presenter only realised how serious the problem was when he returned to Britain, and his doctor was shocked.
Nick explained: "It wasn\'t until I flew back to the UK and I went to see my GP in Northamptonshire to have a yellow fever jab for my next trip that I told him that I hadn\'t been able to see properly and I wasn\'t feeling great.
"He took my blood pressure and it turned out to be really high. He looked really alarmed and said to me, \'Good God, how long has this been going on for?\'
"He said I was dangerously close to having a stroke and he would have to put me on hypertension pills but I should get my eyes checked as well.
"I went straight to Moorfields Eye Hospital in London where it was confirmed I was an inch away from having a stroke and that instead of the blood vessel bursting in the brain, it had popped behind the retina of my right eye."
Nick has been taking hypertension tablets ever since following the scare.
He explained: "They said it had been a near miss and, if it had gone undetected, it would have gone into the brain.
"I was fortuitous to be in the right place at the right time and I\'ve been taking hypertension tablets since."
