According to a WHO study published in 2009, almost 160 million people in the world's poorest countries suffer from uncorrected vision problems, often caused by what is known as "refractive error". Around 9 million of these people have gone blind, despite the fact that the problem, which is fundamentally one of short- or long-sightedness, can be corrected very easily with glasses.
The study also revealed that the global annual productivity loss due to uncorrected refractive error is estimated at 269 billion dollars, almost half of which is lost in the countries of the Western Pacific Region alone.
The reason for this is that people are less productive than they would be if they had glasses to give them normal vision. For example, although the most productive years of a person's working life begin at 40, close manual work becomes more difficult at this age, even for those with good eyesight, while delicate work with small instruments is all but impossible for the visually impaired. In addition to this, experts believe that, given the continuing spread of urbanisation, the problems caused by the increase in cases of defective vision can only get worse.
This is the situation that Joshua Silver, inventor and professor emeritus of atomic physics, is determined to alleviate with his self-adjustable eyeglasses, which he began developing in the mid 1990s.
It is not only productivity and quality of life which suffer as a result of visual impairment. The effects of correctable refractive error can actually be life-threatening. Poor vision can lead to accidents at work, in the home and on the roads. It also closes off many opportunities in education. People with vision impairments may not learn to read, even when given the opportunity to do so.
Poverty and lack of education are, however, only two of the factors involved. Optometrists - or rather, a lack of them - play a surprisingly central role. In Europe, there is one optometrist for every few thousand people (in the UK the ratio is 1:8 000, and in Germany 1:7 000). In Ghana, on the other hand, the number is just one for every million people. Statistically speaking, this would mean an average wait of 200 years for a first appointment. The situation in Mali is even worse, with only one optometrist for every 8 million people.
What is remarkable about Silver's invention is that it allows wearers to adjust the glasses to suit their eyesight, using only a basic test and without the need for an optometrist. To achieve this, the inventor, now also the director of the Centre for Vision in the Developing World, has made use of a simple technique which mirrors the way the human lens works. "Essentially, what we have here is a chamber with a small amount of fluid between two plastic membranes", explains Silver. Turning a small wheel forwards forces fluid into the chamber, causing the surface to swell outwards and producing plus lenses for use by long-sighted individuals. Turning the wheel in the other direction causes the opposite effect, resulting in minus lenses for the short-sighted.
Thanks to this simple construction, it costs just 13 Euros to produce one pair of glasses. Silver's goal is to bring the unit cost down to less than 1 euro, by means of mass production. By comparison, the cost of an eye test and a pair of glasses in Europe is between 250 and 600 Euros, depending on the country. "This invention was designed to benefit everyone who needs vision correction," says Silver, "in particular those people in the developing world who need but do not yet have eyewear." Silver's invention has already helped around 40 000 people in over 24 countries.
Kevin White, who has helped organise the distribution of thousands of pairs of the glasses as part of an American humanitarian programme, has described the recipients' response to the immediate improvement in their vision. "The reaction is universal", says White. "People put them on and smile. They all say, 'Look, I can read those tiny little letters.'"
The patents for his inventions are important to Silver not only in terms of ensuring the quality of his products, but also from the point of view of safeguarding his humanitarian mission. "A venture capitalist once called me at my office," he reveals. "He said that I shouldn't be using my invention in Africa, but in Palo Alto or somewhere like that. When I didn't agree with him, he got really angry." For Silver, patents are way of making sure that his developments are used in the way he wants them to be used.
Glasses are regarded as one of the five most important inventions in the history of humankind. According to American economic historian David S. Landes, their development in the Middle Ages was one of the reasons why Europe subsequently came to dominate the world: "Europe enjoyed a monopoly of corrective lenses for three to four hundred years. In effect they doubled the skilled craft workforce, and more than doubled it if one takes into account the value of experience."
The first recorded use of magnifying glasses can be found in Egyptian hieroglyphics dating back to the 6th century BC. But it was not until around 2 000 years later, at the end of the 13th century AD, that a visual aid for both eyes was invented, in Tuscany, in the form of reading glasses to be placed on the nose. As far back as the early 17th century, French philosopher René Descartes was well aware of the value of vision and the inventions that had helped him: "All the management of our lives depends on the senses, and since that of sight is the most comprehensive and the noblest of these, there is no doubt that the inventions which serve to augment its power are amongst the most useful that there can be."