March 2010 - Adaptive Eyewear for the Third World
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When he founded the museum in 1901 J. H. Sutcliffe was determined that it shouldn't just be a collection of antiques but a reference repository for all that was new and innovative in the subject. Sometimes museums collect items that might represent what the future holds...we could prove to be mistaken, but it is still a point of significance that, at a given point in time, a particular object was thought to point a fresh way forward.
Such is the case with this month's object, donated recently to the museum by the developers. These adaptive spectacles or 'Adspecs' by Adaptive Eyecare Ltd were created at the Centre for Vision in the Developing World at the University of Oxford and introduced to the world in 2003. Featuring highly innovative liquid-filled variable focus lenses, they were designed by an engineer, Josh Silver and tested in Africa and Asia with support from the UK Department for International Development. They were not developed as a conventional commercial product. They are intended to serve very large populations with little access to refraction services and they can, of course, only correct spherical ametropia and not astigmatism. Such spectacles would only be suitable for adults as children have a vastly increased range of accommodation.
No one is claiming that these are an item of designer fashion eyewear. The frame is of a thick dark brown plastic imitation shell with a very traditionally shaped keyform pad bridge. The design is optimised to accommodate the liquid-injection system and screw-operated sealing valves. The reinforced drop-end sides support fluid-filled syringes with adjusting wheels and are connected by lengths of transparent plastic tubing to the hollow round 'lenses' which are two membranes with a space between that the chosen amount of liquid (refractive index of 1.579) is injected to fill. The syringes are then removed of course...it would be too much to expect the poor user to wear something on which they were still in place!
These spectacles were supplied together with a near vision illiterate 'E' chart pasted to inside of lid. It should be viewed as the complete kit of testing chart, self-adjusting lens and finished spectacle frame. In twenty years' time it will be interesting to see what became of them.
References:
Bennett, A.G., 1973, 'Variable and progressive power lenses', Manufacturing Optics International, February, 88-91 (for a muchearlier attempt at variable lenses!)
Silver, J.D., Douali, M.G., Carlson, A.S. and Jenkin, L., 2003, 'How to use an adaptive optical approach to correct vision globally', S Afr Optom 2003 62 (3) 126-131.
Douali, M.G. and Silver, J.D., 2004, 'Self-optimised vision correction with adaptive spectacle lenses in developing countries', Ophthal. Physiol. Opt. 2004 24: 234-241.
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