The human eye, as the spectacles industry shows, is astonishingly imperfect. We cannot blame evolution; our primitive ancestors must have had perfect vision for their spacious world. But then civilization invented craft-work, reading and other close-up activities. Young eyes had to adapt to very short distances. Daedalus surmises that such repeated stresses on the lens of a growing eye give rise to short-sightedness, and possibly astigmatism too.

Now almost every organ of the body is flexible enough to adapt to the demands made on it. Why does the eye alone persist in useless errors such as astigmatism? One theory blames the invention of spectacles. Once an optometrist has prescribed corrective lenses for your eyes, they are fixed in their imperfection. Any changes they might make will make your vision worse; so they have no ‘motive’ for improvement. Daedalus now has a remedy.

These days, he points out, children (and indeed many adults) spend most of their waking hours in front of TV, computer or games-machine video screens. So he is devising a screen which appears at optical infinity, like the ‘head-up’ display in a fighter cockpit. For the dwindling numbers of young book-readers, a similar infinity book-viewer should also be possible. Users of these devices should reach adult life in much better ophthalmic shape.

To correct remaining errors, Daedalus recalls a flexible spectacle lens he once invented, made of the piezoelectric polymer PVDF. It was deformed into the desired shape by a pattern of voltages applied through transparent electrodes and maintained by a small battery-powered circuit. As the wearer's eyes altered, his optometrist simply updated the voltages. Daedalus now reckons that these cunning spectacles should be set so as to under-correct the wearer's vision slightly. His eyes will therefore have an incentive to ‘learn’ the slight adjustment needed for sharp vision. When they have done so, the ‘training glasses’ will be under-corrected again, provoking further adaptation. In due course the glasses will be reduced to plane lenses. They can then be discarded, for the wearer will have perfect vision.

Thus the optimization mechanism, which our eyes must possess, will be put to good use at last. We will recover the keen vision of our distant ancestors, at least until middle age when our lenses start to harden. Even then, Daedalus's training glasses may be able to encourage a valuable extra degree of optical flexibility.