Karlsson, having already sat out the US Open and Open, was back playing in Malmo yesterday, but only for a pro-am – and not very successfully.
When the SAS Masters begins at Barseback today, the 39-year-old Ryder Cup star will be giving a clinic for youngsters before returning to his Monaco home for further tests.
Suffering from a stress-related blister behind the retina of his left eye – it affects both his vision and his balance – Karlsson’s last tournament was the European Open at the end of May.
“I think it’s got a little bit better, but it’s moving slower than I was hoping for and I was also hoping for better on the course today,” he said after only his second full round during his long lay-off.
“It wasn’t good. Standing on the first tee I thought it was going to be fun, but after three or four holes I hit it fat and thought ‘What’s the use?’
“Bunker shots are difficult and when the ball’s in the rough I almost have to look from the side to check how it’s lying.
“I’m looking forward to getting back playing when I’m fully fit, but it’s not really tempting when I can’t do my best.
“I’m still hoping I might be okay for the PGA next month but I’ll know better after some more pictures have been taken of my eye on Friday.”
Karlsson, down from sixth to 18th on the world rankings already this year, has been told the condition can take six months to clear up.
With Karlsson not playing even more attention will fall this week on world number seven Henrik Stenson.
Stenson was in contention at Turnberry last week until finishing his third round with a double bogey six.
The 33-year-old complained that the crowd and metal fencing were far too close to the landing area on the 18th.
Level par at the time – Tom Watson and Stewart Cink played off on two under – he said: “I was trying to hit a long iron down the right-hand side, but blocked it a bit right and hit a guy in the head.
“Without the crowd and the fencing I would have been another 60 yards up in the semi and would have had a fairly easy shot to get on the green.”
This week’s course is the longest in European Tour history at 7,665 yards, 22 yards longer than Torrey Pines was for last year’s US Open.
Another Swede, Peter Hanson, is the defending champion and yet another, 44-year-old Jesper Parnevik, returns from the US Tour to play on the course where he won in 1995.