Doctors and specialists have been working to diagnose the symptoms of a mysterious illness that has the former PGA Tour player laid up in a Melbourne hospital.

Lyle underwent a bone marrow transplant in December following a recurrence of acute myeloid leukaemia last year.

Following on from wife Briony's recent social media updates about his health, Lyle phoned in from his bed to talk with SEN Radio on Wednesday.

"We're having every test known to mankind to try and figure out what's going on," he told Afternoons with Andy Maher program.

"One of the head neurologists said that this is a very, very, very rare thing that he's only ever seen twice.

"This could be something I unfortunately live with for the rest of my life or it gets better with the treatment protocol that they figure out.

"I'm hoping it's the second version, that it is reversible and I'll be able to get on with life again.

"But you've got to have that worst case in the back of your head that it's not and you've got to live with blurred vision.

"Not being able to drive and not being able to look after your kids that well and look after yourself that well either. It's a bit of a tough pill to swallow."

Lyle has has twice beaten cancer - in 1998 and 2012 - and been able to return to play professional golf.

But this latest battle is shaping as his toughest as he deals with the extra complications.

Despite periods of feeling down about his health, Lyle remains determined as ever.

"I guess I've still got that fighting spirit that I've always had and I want to get through it," he said.

"I want to help other people realise that no matter how bad it gets there's always that light at the end of the tunnel.

"I'm looking for that light, I can't see it at the moment but I know it's there."

Australian Associated Press