A scientific study at the University of Queensland has shown that vision really does improve when spectacles are removed.
Postdoctoral research fellows Dr Mark Mon-Williams and Dr James Tresilian of the Human Movement Studies Department have published research findings in a prestigious international journal suggesting that the brain can compensate for optical blur.
Despite the findings, the researchers emphasise that people should not be quick to toss away their glasses.
The work, which has potential application in eye surgery, expands understanding of how the brain processes images. It also provides a scientific basis for anecdotal reports by spectacle wearers that their vision improves after they remove their glasses.
Such reports have traditionally been explained as the spectacle wearers "just getting used to the blur".
Dr Mon-Williams and Dr Tresilian have shown, however, that there really is a genuine improvement in eyesight - people can actually see better after about 30 minutes of exposure to blur.
Dr Mon-Williams and Dr Tresilian took people with perfect eyesight, made them short-sighted with special spectacles, measured eyesight levels through the special spectacles, then let participants watch blurred television for half an hour.
After the half-hour period they remeasured the eyesight through the spectacles and found a considerable improvement - equivalent to about two lines on a standard eyesight chart.
A series of control experiments measured sensitivity to special gratings of different contrasts in people with perfect eyes made shortsighted. They suggested that the improvement in eyesight was not caused by any psychological or optical factors but was due to the brain tuning itself to give the best possible image through the blur.
"Essentially it is like tuning a television set to give the best picture from the incoming signals," Dr Mon-Williams said. "It isn't possible to improve the strength of the signals that arrive at the back of the eye but the brain can adjust its sensitivity to maximise the quality of the image."
The findings have been featured on the front cover of a premier scientific international biological journal - The Proceedings of the Royal Society.
The University of Queensland photography section produced the cover photograph that showed an eye that was digitally blurred on the right hand side becoming progressively clearer towards the left side of the picture.
Dr Tresilian warned that the findings did not mean that people should discard their spectacles.
"The brain can only compensate for blur but not remove it entirely," he said.
"If people need spectacles then they can wear them safe in the knowledge that they will not make their eyes worse. The study provides the first scientific evidence that eyesight does not deteriorate as a result of wearing spectacles.
"The fact that uncorrected eyesight is better after a period of time without spectacles is due to neural compensation and not because of any changes in the eye."
The Australian Research Council-funded study was completed in collaboration with Dr John Wann at the Psychology Department, University of Reading, England, and Dr Niall Strang at the Centre for Eye Research, QUT.
For further information, contact Dr Mon-Williams or Dr Tresilian, telephone 07 3365 6817, email markmw@hms.uq.edu.au, or jamest@hms.uq.edu.au
