Vrije Universiteit: U-Spec spectacles

Around half the world's population has the kind of eye problems that could benefit from the wearing of spectacles. In many developing countries, however, glasses are either unavailable or too expensive, and there is also a lack of personnel trained to administer eye tests. Without help, many people suffer deteriorating vision and become practically blind. Dutch researchers hope to help with a new invention called the "U-Spec", or "universal spectacles" — very cheap glasses that can be adjusted by anybody to suit their own eyesight.

The white plastic, rigid-framed test model of the U-Spec still has a long way to go both technically and aesthetically, as its inventor Rob van der Heijde concedes. He is a physicist who specialises in the workings of the eye, based at the Free University Medical Centre in Amsterdam. Dr van der Heijde developed the concept of the adjustable spectacles with the assistance of one of his students:

Shifting power
This report was featured in Research File. Listen to the programme in full. (29:30)

"We want to go further but we need technical support to make the lenses as thin as possible and the moving parts as good as possible," he says. He explains that the adjustability of the U-Spec depends upon one pair of shifting lenses per eye. Whereas normal spectacles contain fixed, single lenses, the U-Spec lenses are formed from two complementary parts mounted together. The complexly curved surface of these parts resembles a saddle, with a hollow to one side and a little "hill" to the other. These two parts can fit together with the hill of one sitting in the hollow of the other, but they can also slide apart in opposite directions. The key thing is that in any configuration they together form a viable lens for assisting defective eyesight, with the power of the lens changing depending on their position.

The top figure shows one element of the Alvarez lens; the bottom shows how the two lenses fit together to form one adjustable lens

It may sound complicated, but for the wearer of the U-Spec adjusting the lenses couldn't be easier. You simply close one eye at a time and find the correct focus for the other by sliding a small knob up and down in a vertical slot in the frame, next to the lens in question.

DIY optometry
"People wearing these spectacles can look at a far away object and move the knob until they have it sharp," says Dr van der Heijde. "You don't need a specialist to get good spectacles, you can do it yourself — and that's a good opportunity to have in Third World countries."

Dr van der Heijde is keen to point out that the shifting saddle-shaped lenses are not actually his own invention, but were conceived by Nobel Prize-winning physicist Luis Alvarez, whose patent on the system expired in recent years. That allowed Dr van der Heijde to work on his own idea of incorporating these lenses into a pair of spectacles. But he says there are other reasons why development still has a way to go: "For a long time it was impossible to make those strangely formed lenses and nowadays it's possible by cheap methods. The only thing is that you need a very good mould of optical quality and that is very expensive."

Sophisticated equipment
The moulds for the lens parts would have to be made in wealthy, western countries because sophisticated lathes are needed to create the three-dimensional surface with high enough accuracy. But Dr van der Heijde thinks such moulds could then be shipped to developing countries so that the U-Specs could be manufactured there, resulting in a low-cost product: "We calculated it's just one to three euros, depending on materials and so on."

Rob van der Heijde with a pair of U-Spec spectacles

The U-Spec project has caught the eye of the World Health Organisation (WHO) and its specialist sub-organisation, Vision 2020, which is committed to improving visual health around the world. But while Dr van der Heijde is gratified by their approval, he stresses that the project still needs practical support if it's to develop further. "It takes about half a year to make a prototype," he says. "The WHO helps us by saying that they like the project very much, but they don't give money. So the main part of our programme in the next months is to get funds from everywhere."