The standard approach in the developed world is for people with a vision impairment to visit an optician for an eye test. They are given a prescription, the lenses are produced and they can choose the frames they would like from a shop. In this scenario one relies on the presence of trained opticians and the infrastructure to produce and distribute the required materials. But these are not present in many parts of the world. “Roughly speaking, in parts of sub-Saharan Africa there’s going to be about one optician per million of the people,” says Silver.

To get round this limitation, Silver – who is an atomic physicist at Oxford University – developed a concept in the 1980s for glasses that can be self-tuned to meet an individual’s prescription. The basic idea is that each lens consists of two flexible membranes filled with a liquid. So, by adding or removing fluid, the shape and thus the power of the lens can be adjusted by the individual wearer.

In this podcast, Silver talks about how the first incarnations of his so-called Adspecs have already made a huge difference to individual lives in some parts of the world. But he has also been busy developing the technology to improve the quality and make it more accessible. Silver’s team at the Centre for Vision in the Developing World is now producing an updated version of the glasses called “New Adspecs”, which make it easier for individuals to set their own prescriptions. Some 500 pairs of these were distributed to Syrian refugees in Jordon in 2014. He is also looking to develop new styles of glasses, which could also help to improve the uptake of the technology.

Silver was interviewed by Physics World reporter James Dacey at the UNESCO headquarters in Paris during the opening ceremony of the International Year of Light (IYL 2015). Find out more about that event and some of the other light-based technologies in the spotlight this year in this short film.

Also, don’t forget to check out our pp01.agh.sleek.net/physicsworld/reader/#!edition/editions_light-2015/article/page-5383">free-to-read digital collection of 10 of the best Physics World features related to the science and technology of light, including an in depth article about Silver’s Adspecs initiative.