PIONEERING Scots researchers have launched a pocket-sized device which could prevent millions of people in poor countries from losing their sight or hearing.

The breakthrough tool, known as the 'Arclight', is being trialled in parts of Africa and Asia to screen patients for the onset of blindness-causing eye disorders such as diabetes, cataracts and glaucoma, as well as retinoblastoma - a rare but potentially fatal type of eye cancer which mostly affects children under five, but which can be cured in 95 per cent of cases if identified early.

The device is also being used in Malawi to detect and treat ear conditions which can lead to deafness, and is already being sold to medical schools and GPs in the UK to help diagnose eye and ear diseases after preliminary studies showed that it was more effective that existing machines which cost hundreds of pounds more.

Profits from the sale of the device are being used to cross-subsidise its price in poor countries, where it can be marketed to hospitals and community-based medics for as little as £5-10 each.

The Arclight has been developed over the past 16 years by a team led by scientists from St Andrews University, in collaboration with experts from University College London and Leicester University.

Dr Andrew Blaikie, an NHS eye surgeon and academic in St Andrews University's School of Medicine who helped spearhead the project, said: "All diagnostic devices tend to be developed for rich economies because that's where the profits are. But this shows that if you design something frugal for low-income countries you might get lucky and create something cheap and effective which is actually still useful in a rich country. This is the classic example."

Thousands of units have now been distributed around the world to countries including Malawi, Ethiopia, Kenya, Tanzania, Rwanda, Ghana, Fiji, Indonesia, and the Solomon Islands, through a collaboration with the Fred Hollows Foundation and the International Agency for Prevention of Blindness.

The Arclight incorporates an LED light with an ophthalmoscope, otoscope, and loupe into a single handheld package smaller than a mobile phone. Its unique size and design also mean it can be powered by a slim lithium battery charged by a tiny integrated solar panel, eliminating the need for electricity or plug-in points.

It is a far cry from existing ophthalmoscopes - the cumbersome devices commonly found in high street opticians which examine the interior of the human eye for disease using light beams to illuminate otherwise invisible tissues.

Although first invented in the 1850s, their design has barely changed in more than a century and the Arclight is the first device of its kind to combine an ophthalmoscope with with an otoscope - which checks the ear canal and drum for damage - and a loupe, a type of magnifying device.

Few practitioners in poor countries have access to these tools, however, even though they have the highest rates of vision and hearing loss - the majority of which could be prevented if caught in time.

The Arclight can fill that gap as a cheap and simple on-the-spot diagnostic tool.

Dr Blaikie added: “Arclight is the result of years of hard work by a small team of enthusiasts. These efforts have brought simple, frugal yet highly effective tools to health care workers who would otherwise be unable to make the early diagnoses needed to prevent needless blindness."