It's not clear how Chapman's blurry eyesight of half a century has been replaced by perfect vision almost overnight.

Chapman wore long-distance and bifocal glasses for decades. His sight was particularly bad in his left eye, and he's had treatment for cataracts in both.

Then he tripped over his shoelace while walking the dog, and suddenly his world changed.

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Chapman didn't hit his head in the fall, but he severely bruised his left side. However he says it was worth the pain as the next morning he woke up and could see and hear better than he had in decades.

"I couldn't believe it. It was quite incredible to me. As soon as I opened my eyes in the morning, everything was changed. I could see with amazing clarity," Chapman said.

Thinking his restored vision may be temporary after the September fall, Chapman kept quiet, but now he believes it's here to stay, and he's happy to boast about his new lease on life.

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"It's miraculous. That's the only word you can use for it I suppose," Chapman said.

His hearing is still sharp too. But there's always a downside to changes late in life.

"I became aware of it the following day when I was out with (dog) Flossie. The fire station is just around the corner and the fire brigade came past with all sirens blaring and my ear drums were actually paining. I had to put the fingers in my ears and press hard," Chapman said.

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Roman Serebrianik of the Australian College of Optometry considers Chapman's 'cure' a bit of a medical mystery.

"It's unusual almost possibly to the point of being unique," Serebrianik said.

"We certainly do see vision changes after a fall, but it's more unusual for it to improve rather than to get worse. It's hard to say why that happened, but the main thing is that he's well, he recovered after his fall, and his worse eye is now a little bit better."

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It's made a vast difference to Chapman's everyday living.

"Reading is one thing - fine print and things like that, without having to go rummaging through for glasses and all this business," he said.

"And to walk along the street and see the difference. You can never get the same clarity with glasses as you can with good vision."