Wearers can adjust the strength of the lenses themselves by turning wheels on the side of the spectacles

Berber Rouwé

Spectacles with variable lenses that can be adjusted by a wearer with no access to specialist eye care are being mass produced.

The first 30,000 pairs will be shipped to Afghanistan, Ghana and Tanzania by the end of the month.

Focusspec is the first self-adjustable lens to be produced in large quantities, though other similar glasses have been designed. The technology is expected to improve the lives of millions of adults in the developing world living with poor eyesight.

The spectacles were developed by Dutch industrial designer Frederik Van Asbeck, based on a discovery in 1964 by Nobel Prize-winning physicist Luis Alvarez. Alvarez designed a lens that was convex on one side and concave on the other. He found that by placing two such lenses on top of each other, and moving one relative to the other, the focus could be changed.

"The technology to produce those lenses with the needed high precision — an aberration of a micrometre will cause a headache — was developed only a few years ago," Van Asbeck told SciDev.Net.

Anyone can adjust the strength of the lenses themselves, by turning wheels located on the side of the spectacles, eliminating the need for an eye expert.

Van Asbeck says Focus on Vision, serving the WHO's VISION 2020 programme, will produce one million pairs of glasses a year in the Netherlands.

The glasses have been tested in Afghanistan, Cambodia, Ghana, India, Nepal and Tanzania.

"I see people's faces light up when they adjust their spectacles and discover they can read again, take care of themselves, work, get an education," says Jan in 't Veld, a board member for Focus on Vision, which undertook a large part of the fieldwork.

In 't Veld says the lenses are scratch-, UV-, water- and dust-resistant — and optically almost as good as the far pricier lenses used in Western countries.

Ben van Noort, co-board member and ophthalmologist, points out that Focusspec lenses can only be adjusted between +0.5 to +4.5 dioptre or -1 to -5 dioptre (most people wear between -6 and +6) and they are unsuitable for astigmatism. "Still, they work for 80–90 per cent of adults," he says.

Lillian Mujemula, optometrist and main distributor of the glasses in Tanzania agrees: "Most of our clients live in remote areas, where there are no optometrists. People are very happy with the glasses because they are of good quality and easy to use. I believe people can wear them for many years."

Brien Holden, professor of optometry in Sydney and chairman of the International Centre for Eyecare Education (ICEE) told SciDev.Net: "The FocusSpec has an important place as a stop-gap solution. But they cannot replace the long-term strategy of educating eye care personnel and creating optical workshops and distribution channels in each community in need".

Holden also points out there is a need for proper scientific field studies, which ICEE is now in the process of designing.

The spectacles are expected to be sold at local shops, schools and health centres for US$3–5 a pair.