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Self-adjustable eyeglasses: how one man's vision is helping others to see better

Self-adjustable eyeglasses: how one man's vision is helping others to see better

Though common in the US, refractive error such as nearsightedness is a highly treatable condition; with a simple visit to an optometrist, one can receive a pair of eyeglasses or contact lenses that can help correct poor vision. For people in developing countries, it is not so easy; with only one optometrist for every 600,000 people on average, most people with refractive error go untreated. But one professor has come up with a solution: self-adjustable eyewear.

One afternoon in March 1985, Prof. Joshua Silver, an atomic physicist and professor of physics at the UK's University of Oxford and founder and director of the Center for Vision in the Developing World (CVDW), was having tea with a friend.

"Can you make an adjustable focus lens?" his friend asked. "My initial response was 'no,'" Prof. Silver told Medical News Today. "Then I said, 'oh yes,' and I made one that afternoon, and I've still got it."

With some tweaks, Prof. Silver developed a lens he could use to correct his own nearsightedness, or myopia, with high accuracy.

"This lens took 10 minutes to make, and I could get very clear vision with it without any practitioner," he told us. "In other words, I found a route to delivering vision correction to myself at very low cost and without the need for any help from a professional. That was really the starting point."

Twenty years on, Prof. Silver's first model of self-adjustable glasses - named Adspecs - has been distributed to more than 60,000 people across 20 developing countries.

Prof. Silver has also teamed up with Dow Corning - a leading global supplier of silicon-based technology - to launch the Child Vision project, which aims to distribute a newer model of self-adjustable glasses designed specifically for young people aged 12-18 years old in developing countries with refractive error.

Prof. Silver is not the first person to come up with the idea of self-adjustable eyewear; it was first proposed back in 1879. "It's just that no one had taken it as far as I took it," he told MNT.

"I had an advantage over some people who worked on this," he added, "which is that I am a physicist and I have also have taught optics at an undergraduate level and advanced level to students and university doctors, so putting two together, I was well placed, I suppose, to take the technology forward."

How do the glasses work?

Refractive error occurs when the shape of the eye stops light entering the eye from being correctly focused.

Myopia is one of the most common forms of refractive error, impairing a person's ability to clearly see objects that are far away. It may occur if the eyeball is too long or there is too much curvature in the cornea - the transparent layer covering the front of the eye. Such abnormalities result in blurred vision when looking at distant objects.

Both the Adspecs and the newer model of self-adjustable glasses work on the same principle to correct refractive error; they consist of a fluid-filled lens technology that allows the wearer to adjust the power of the lens until optimal vision is reached.

Each lens is made of two flexible membranes that move either inward or outward depending on the amount of fluid - a silicone solution - they contain.

The lenses are connected to a small syringe that sits on each arm of the glasses, and the wearer can adjust a dial on the syringe to pump fluid in or out of each lens. When fluid is pumped in, the power of the lens is increased - correcting hyperopia, or farsightedness - while pumping fluid out decreases lens power, correcting nearsightedness.

Put simply, changing the physical shape of the lens by pumping the silicone fluid in or out alters its refractive power - the extent to which a lens bends light as it passes through the eye - allowing the wearer to correct their own refractive error.

When the wearer has finished adjusting the glasses, the syringes can be removed, leaving them with clearer vision and what looks like a standard pair of spectacles.

A life-changing creation

Numerous studies have demonstrated the efficacy of Prof. Silver's self-adjustable glasses.

Published in The BMJ in 2011, one study tested Adspecs in almost 650 schoolchildren with myopia aged 12-18 in rural China, while another 2011 study published in the journal Opthalmology tested the glasses in more than 550 Chinese teenagers with myopia aged 12-17.

In both studies, it was found self-refraction through use of the eyewear significantly improved vision for around 95% of participants. What is more, they found the technology simple to use.

More than 100 million adolescents aged 12-18 in the developing world have myopia, and it is estimated that around 60% do not have access to treatment for their condition. Not only can this be detrimental to their overall quality of life, it can have a severe impact on their education, social participation and employment.

But, as demonstrated by his research and through his own experiences, Prof. Silver's creation has life-changing capabilities. He told MNT:

"I still remember the very first pair that I deliver to a gentleman in Africa, whose name is Henry. He couldn't work anymore because he couldn't see close up. I gave him a pair of glasses adjusted for his vision and he started working again. It effectively changed his life because it meant he could earn a living."

On the next page, we look at the cost of producing the self-adjustable eyeglasses and learn more about the Child Vision project and what Prof. Silver's goals are for the future.

Reducing the cost of production

One major barrier to introducing any form of technology to developing countries is cost, and this is something that Prof. Silver has had to consider from the beginning.

Back in 1996, Prof. Silver approached the then director of the World Program for the Prevention of Blindness at the World Health Organization (WHO) Dr. Bjorn Thylefors with his idea. Though enthusiastic about the creation, one stipulation was the glasses had to be affordable for developing countries, at around $1 a pair.

Though that target has not yet been reached, progress is being made. The first Adspecs design cost around $18-19 to produce, and Prof. Silver personally subsidized each of the 60,000 pairs distributed by around $5 - something he did not realize until after.

The cost of production is gradually falling, and Prof. Silver told MNT he currently has a friend who works for the world's largest eyeglasses producer embarking on a project to reduce the cost further.

"I set him a challenge to make them for about $3 and he hasn't quite got there, but the price keeps coming down," he said.

Still, the production cost of the technology itself is minimal relative to how much it would cost for adequate access to an eye care specialist in developing countries.

"The whole point about this technology is that you don't have to pay for an optician," explained Prof. Silver, "and so the cost of getting a pair to a user is more than the bare cost you are talking about, but is much less expensive than the traditional way of making eyeglasses."

At present, the cost of production and delivery of one pair of glasses to a child in the developing world totals around $15.

The Child Vision project

On the back of studies showing the efficacy of Adspecs for correcting refractive error in adolescents, Prof. Silver was approached by Dow Corning, who offered $3 million funding and materials to make a new, improved version of the eyewear specifically for young people - referred to as "Child Vision" glasses.

These glasses work in the same way as Adspecs, but they are more suited to teenagers in terms of how they fit and look; the newer model is available in a range of colors.

The first phase of the project started in 2013, in which CVDW and Dow Corning aimed to distribute around 50,000 pairs of the Child Vision glasses to children in need across the developing world.

To date, around 4,000 pairs have been distributed, but Prof. Silver says they are making progress; production has been scaled-up and they now have the capability to make up to 1 million pairs a year.

The glasses are delivered through a distribution program that involves teaming up with schools in developing countries. Teachers in the schools receive 1-2 hours training on how the glasses are adjusted, enabling them to show the children how to use them.

"You don't need much training." Prof. Silver noted. "If you train the teacher for several hours in how to apply them, they can then train children in class, so it is a very intuitive thing to do."

Prof. Silver stressed that the glasses have been rigorously tested prior to being delivered for use.

"You should not distribute any self-adjustable eyewear until it has been tested at least to the standard of our published research, which means running a clinical trial of at least 500 people and looking at how well the particular device you've got works," he told us.

"The ones we have created, we know they work, and our process and our recommended procedure is that everything should be clinically trialled before you actually deliver them."

So what is the long-term goal with the Child Vision project? "The goal is to get the 100 million children who need glasses for their education to be corrected as quickly and as is feasible," said Prof. Silver. "But it is a question of how much funding is available for it."

"The device works and the procedure works, so it is how many can you make and it's finding the funding to solve what is a very big international development problem," he added.

CVDW and Dow Corning have set up a charity to raise funds to take the Child Vision project forward. A £10 ($15) donation will pay for a pair of self-adjustable glasses for one child in the developing world.

The future for self-adjustable eyewear

In developed countries such as the US and the UK, access to an optometrist is not normally an issue. This begs the question: would self-adjustable eyewear work in such countries? And would opticians be willing to sell such a product?

According to Prof. Silver, the answer to both of these questions is "yes."

"Optometrists have a very important role; their role is not so much to provide you with glasses, it is to monitor your eye health," he told us. "It's very important to have access to optometrists and this is a device that can be sold through optometrists in the developed world, but when it becomes known that they are not very expensive, hopefully optometrists will sell them at a low price."

Source: medicalnewstoday.com


  • 13.11.2015
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