The world in focus
If you have faulty eyesight, getting it corrected is relatively straightforward — assuming you live in the developed world. But in poorer countries the network of optometrists, ophthalmologists and glasses makers is either inadequate or non-existent. In parts of sub-Saharan Africa, there is one optometrist to every million people, compared with one to every 4000 in the UK. People there have little choice but to make do with poor vision, and all the social and economic consequences that brings.
Hundreds of millions of people worldwide are visually impaired. Only a fraction of them receive vision correction, though, and most of those are in the developed world. Physicist Joshua Silver is trying to do something about it. While playing around with adjustable lenses one day, he discovered that he could correct his own slight near-sightedness, and that gave him an idea.
Silver set up a company to produce low-cost adjustable spectacles that can correct the vision of both far-sighted and near-sighted people. Now that the spectacles have been trialled in Africa and Asia, Silver tells Justin Mullins how they could help up to a billion people with vision problems in the developing world — and how atomic physics led him to the idea
How does an atomic physicist get involved in vision correction?
I have a habit of developing little bits of technology that interest me. I came to vision correction while playing around with certain types of lenses and mirrors that have the particular feature that you can change their power easily.
But what have lenses got to do with atomic physics?
Atomic physicists use light to study the properties of atoms, so we need optical elements such as mirrors and lenses. Optics is an integral part of experimental atomic physics.
How do these lenses work?
Each lens is a fluid-filled chamber bounded by a thin, clear plastic membrane. By changing the amount of fluid in the chamber, you change the curvature of the membrane. So what you have is a lens with variable power.
It's one thing playing around with variable-power lenses. It's quite another turning them into spectacles. How did that happen?
I'm slightly myopic. I need my vision corrected by about a dioptre and a half in each eye — a dioptre is a unit of measurement of the power of a lens. I found that if I looked through the lens I had made and changed the power, I could accurately correct my own vision. That made me think that this could be a way for other people to do the same.
It also made me wonder how many people there are in the world who need vision correction and don't have it.
How many are there?
In 1994 I met up with Björn Thylefors, an ophthalmologist who was, at that time, director of the World Health Organization's blindness prevention programme in Geneva. He said the number was about a billion. In our first conversation, I somewhat arrogantly told him that I thought I had a method which could deal with that problem. He said to me, "If you can do that, you should." And that set me off.
How do you correct the vision of so many people?
In the developed world, you go to an optometrist to get a prescription, the prescription is made up into a pair of glasses, and off you go. But that requires an infrastructure and a relatively large number of trained professionals. There is something like one optometrist for every 4000 people in the UK, for instance. In some countries in sub-Saharan Africa, the ratio is one optometrist to a million people. In Mali it's one to 8 million people. You could try to create more professionals, but it's very hard to do that. It would cost a fortune, and the infrastructure is not there for them to slot into. Another problem is that when you train professionals in developing countries, they often emigrate.
What's your plan?
My plan is very simple. If you can make a device that is relatively inexpensive to manufacture and can be self-administered, then you cut out the middleman and the bottleneck in treatment. That is what the adaptive spectacles are all about. My company, Adaptive Eyecare, now has a production line in China that makes these spectacles.
Who is using your glasses?
We've delivered 10,000 pairs to Ghana, which are being given out as part of an adult literacy programme. In Ghana, people were being taught to recognise words in large letters on a blackboard in the classroom, but weren't being given vision correction, and so couldn't read most types of print when they got home. Our spectacles solved that problem.
So if you are sitting in a classroom in Ghana and you are given a pair of adaptive spectacles, how do you correct your own vision?
The amount of fluid in the lens, and hence its curvature, is controlled by a removable syringe. Initially you set the spectacles so that they are at a high power compared to the power you actually need. You cover one eye and look, ideally, at an eye test chart, although other objects can work — such as the leaves on a nearby tree. Then you gradually change the power of that lens until your vision is at its sharpest, and repeat for the other eye. The whole process takes less than a minute. Then you set the lenses and discard the syringe. If you follow the protocol correctly, you should end up with accurately corrected vision.
How accurately can people correct their vision?
The evidence we have so far is that people can self-correct to about the same accuracy as if they were corrected by an optician. The glasses can't correct every type of vision error — they can't correct astigmatism, for instance — but they should work for more than 90 per cent of people requiring correction.
And the cost?
We think that a few days' income is an affordable target, and that varies from country to country. But it means that we need to be able to mass-manufacture the device at a cost in the region of one US dollar or so. Most modern ophthalmic lenses — even very high-quality ones — cost around a dollar, and we've got to be competitive with that. I'm sure we can be. But you've got to remember that there are other costs related to the manufacturing process that have to be taken into account, which makes it complex to calculate the price for the end-user.
How long before you achieve your goal of adaptive spectacles for all who need them?
The WHO has set a target of getting vision correction to most people who need it by 2020. If we've made a significant dent in that number by then, I think we will have achieved our goal.
"People can self-correct as well as if they were treated by an optician"
Profile
Joshua Silver is an atomic physicist at the University of Oxford who studies highly charged ions. He began his work on low-cost spectacles in the mid-1990s. His company, Adaptive Eyecare, is now supplying adaptive spectacles to the developing world (see www.adaptive-eyecare.com).
By: Mullins, Justin, New Scientist
Hundreds of millions of people worldwide are visually impaired. Only a fraction of them receive vision correction, though, and most of those are in the developed world. Physicist Joshua Silver is trying to do something about it. While playing around with adjustable lenses one day, he discovered that he could correct his own slight near-sightedness, and that gave him an idea.
Silver set up a company to produce low-cost adjustable spectacles that can correct the vision of both far-sighted and near-sighted people. Now that the spectacles have been trialled in Africa and Asia, Silver tells Justin Mullins how they could help up to a billion people with vision problems in the developing world — and how atomic physics led him to the idea
How does an atomic physicist get involved in vision correction?
I have a habit of developing little bits of technology that interest me. I came to vision correction while playing around with certain types of lenses and mirrors that have the particular feature that you can change their power easily.
But what have lenses got to do with atomic physics?
Atomic physicists use light to study the properties of atoms, so we need optical elements such as mirrors and lenses. Optics is an integral part of experimental atomic physics.
How do these lenses work?
Each lens is a fluid-filled chamber bounded by a thin, clear plastic membrane. By changing the amount of fluid in the chamber, you change the curvature of the membrane. So what you have is a lens with variable power.
It's one thing playing around with variable-power lenses. It's quite another turning them into spectacles. How did that happen?
I'm slightly myopic. I need my vision corrected by about a dioptre and a half in each eye — a dioptre is a unit of measurement of the power of a lens. I found that if I looked through the lens I had made and changed the power, I could accurately correct my own vision. That made me think that this could be a way for other people to do the same.
It also made me wonder how many people there are in the world who need vision correction and don't have it.
How many are there?
In 1994 I met up with Björn Thylefors, an ophthalmologist who was, at that time, director of the World Health Organization's blindness prevention programme in Geneva. He said the number was about a billion. In our first conversation, I somewhat arrogantly told him that I thought I had a method which could deal with that problem. He said to me, "If you can do that, you should." And that set me off.
How do you correct the vision of so many people?
In the developed world, you go to an optometrist to get a prescription, the prescription is made up into a pair of glasses, and off you go. But that requires an infrastructure and a relatively large number of trained professionals. There is something like one optometrist for every 4000 people in the UK, for instance. In some countries in sub-Saharan Africa, the ratio is one optometrist to a million people. In Mali it's one to 8 million people. You could try to create more professionals, but it's very hard to do that. It would cost a fortune, and the infrastructure is not there for them to slot into. Another problem is that when you train professionals in developing countries, they often emigrate.
What's your plan?
My plan is very simple. If you can make a device that is relatively inexpensive to manufacture and can be self-administered, then you cut out the middleman and the bottleneck in treatment. That is what the adaptive spectacles are all about. My company, Adaptive Eyecare, now has a production line in China that makes these spectacles.
Who is using your glasses?
We've delivered 10,000 pairs to Ghana, which are being given out as part of an adult literacy programme. In Ghana, people were being taught to recognise words in large letters on a blackboard in the classroom, but weren't being given vision correction, and so couldn't read most types of print when they got home. Our spectacles solved that problem.
So if you are sitting in a classroom in Ghana and you are given a pair of adaptive spectacles, how do you correct your own vision?
The amount of fluid in the lens, and hence its curvature, is controlled by a removable syringe. Initially you set the spectacles so that they are at a high power compared to the power you actually need. You cover one eye and look, ideally, at an eye test chart, although other objects can work — such as the leaves on a nearby tree. Then you gradually change the power of that lens until your vision is at its sharpest, and repeat for the other eye. The whole process takes less than a minute. Then you set the lenses and discard the syringe. If you follow the protocol correctly, you should end up with accurately corrected vision.
How accurately can people correct their vision?
The evidence we have so far is that people can self-correct to about the same accuracy as if they were corrected by an optician. The glasses can't correct every type of vision error — they can't correct astigmatism, for instance — but they should work for more than 90 per cent of people requiring correction.
And the cost?
We think that a few days' income is an affordable target, and that varies from country to country. But it means that we need to be able to mass-manufacture the device at a cost in the region of one US dollar or so. Most modern ophthalmic lenses — even very high-quality ones — cost around a dollar, and we've got to be competitive with that. I'm sure we can be. But you've got to remember that there are other costs related to the manufacturing process that have to be taken into account, which makes it complex to calculate the price for the end-user.
How long before you achieve your goal of adaptive spectacles for all who need them?
The WHO has set a target of getting vision correction to most people who need it by 2020. If we've made a significant dent in that number by then, I think we will have achieved our goal.
"People can self-correct as well as if they were treated by an optician"
Profile
Joshua Silver is an atomic physicist at the University of Oxford who studies highly charged ions. He began his work on low-cost spectacles in the mid-1990s. His company, Adaptive Eyecare, is now supplying adaptive spectacles to the developing world (see www.adaptive-eyecare.com).
By: Mullins, Justin, New Scientist
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