'I am at the stage of just praying to finish my round every day,' he said after hitting a painful seven-over-par 79.
Back problems have troubled the 35-year-old Spaniard throughout his career but his condition appears to have worsened.
'I'm worried because I desperately want to compete again,' he said. 'But if I finished right now, I think my career would still be very good.
'I feel as low as it is possible to be right now. I will have to go home and sit down, take my time and think things out.'
It is the first time since 1988 that Ballesteros, the winner of five major tournaments, has been forced to retire from a tournament.
He has also pulled out of next week's Portuguese Open and his participation in the US Masters at Augusta National, starting on 8 April, is in doubt.
The seriousness of his problem could also be a long-term worry for Bernard Gallacher, Europe's Ryder Cup captain, as he prepares for the match against the Americans at the Belfrey in September.
'I knew when I came here that my back was bad, but not this bad. The pain is persistent,' Ballesteros said.
'I have trouble sleeping, I can't practise as much as I want. It hurts when I swing and I can even feel pain when I am putting.
'I have to exercise two hours every day and I have difficulty even in lifting up my children.'
Ballesteros played in obvious discomfort to finish his round, trying afterwards to put a brave face on his problem. 'You know me, I always go to the limit,' he said.
'The Masters is a month away and I hope to be better by then. If I felt like I did on the back nine today I couldn't play, but if I felt like I did when I arrived on Monday then I would go to Augusta.'
Jose-Maria Olazabal, Ballesteros' compatriot and Ryder Cup team-mate, said: 'I hope for two things. . . that Seve recovers from these back problems and that he strikes the ball like he did before. The European Tour needs people like him.'
Meanwhile, four players, Denmark's Steen Tinning, the Argentinian Ruben Alvarez, Ireland's Eoghan O'Connell and the former British amateur champion, David Curry, shared the first-round lead, hitting three-under-par 69s.
Tinning was the first to set the target at lunchtime with five birdies sandwiched in between bogeys at the first and last. Curry then briefly threatened to overtake his rivals when he moved to four under before slipping back.
Hadyn Selby-Green, from Doncaster, hit a hole-in-one at the 186- yard 15th to win two airline tickets to any destination in the world.
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