Adjustable lenses correct refractive vision errors

Engineers at UK-based Adlens have developed adjustable eyeglasses that correct 80 per cent of the refractive vision errors encountered by people in the developing world.

Using SolidWorks software, Adlens created a layered lens that enables wearers to literally dial up custom prescription eyeglasses with no help from an optician, optometrist or ophthalmologist.

Under guidance of a trained person such as a community health worker, Adlens’ adaptive eyeglasses adjust with the turn of a knob to correct nearsightedness, farsightedness and presbyopia (loss of focus).

’There are hundreds of millions of people around the world who need only a simple pair of eyeglasses to remain self-sufficient,’ said Sjoerd Hannema, chief executive of Adlens. ’We are working through the Vision for a Nation programme to raise awareness of the impact impaired vision can have on a person’s education and quality of life. Our product is a way to correct many of those vision problems with the infrastructure available in the developing world.’

Adlens used the SolidWorks software to design a four-layer polycarbonate eyeglass lens. Two rigid lenses enclose a cavity housing, a flexible third lens that contains a volume of oil. Knobs on the eyeglass frames pump the transparent oil in or out of the lens, where the middle layer flexes to provide the optical power the wearer needs. Then the wearer simply removes the levers and the adjustment knobs to lock in the prescription.

Creating a mechanism delicate enough for fine adjustments yet durable enough to survive heat, dust and transportation over long distances was challenging, said Adlens product designer Alex Edginton.

’Structural integrity and durability are significant considerations for us. Rwanda, where we are working with the Ministry of Health to provide our spectacles, has a wide range of environmental conditions. The lenses and adjuster mechanisms are designed and tested to cope with the harsh conditions they will be subjected to,’ he added.

’We’re putting much more functionality than usual into a pair of spectacles with the adjustable lenses, seals and mechanisms, which are assemblies of complex, precision components. Fitting them together optimally was critical.’

Rwanda is typical of sub-Saharan African nations that might have only a handful of eye care professionals to serve the whole country. They usually work in or around the capital cities, mainly treating the wealthy, leaving low-income and rural Rwandans to fend for themselves.

’The simple ability to fit a person with a pair of eyeglasses can lead to a better education for a child, a longer working life or advanced education for an adult, or just the ability to remain independent with age,’ said DS SolidWorks chief executive Jeff Ray. ’Adlens is showing how technical innovation can improve living conditions all over the world.’