Joshua Silver, Centre for Vision in the Developing World
Self-adjustable eye glasses
Self-adjustable eye glasses
[Regions:] Ghana, South Africa, Nepal, and Malawi
Centre for Vision in the Developing World (CVDW) in partnership with government and community based organizations in developing countries for the purpose of field and clinical trials. Most notably, through the Humanitarian and Civic Assistance Program of the US military and the Ghana Education Ministry, Non-Formal Education Division (NFED). Global Vision 2020 is also a partner, providing deployment assistance for CVDW.
Other organizations distributing Adspecs include The Rural Development Centre (RUDEC) in Cameroon and Remote Area Medicine’s (RAM) vision outreach project in Bolivia.
More info. can be found at these sources:
Vision Spring is another organization involved in distribution of glasses in developing countries, although not adjustable glasses. They have trained “vision entrepreneurs” who conduct vision screenings and dispense ready made glasses to bottom of the pyramid customers.
Goal : to improve and promote good health.
[Users:] People in developing countries requiring vision aids, but who likely do not have access to a trained optometrist to obtain prescription glasses.
Adspecs are not currently available for individual purchase. At present, Centre for Vision in the Developing World supplies adjustable glasses only to research and distribution partners for the purposes of clinical and field trials.
Operation: Adspecs are self-adjustable glasses that allow the wearer to tune their glasses to their eyes. To change the power of the lens, the user turns the wheels on the syringes on the arms to pump more or less silicone oil into the lenses (which are simply two flexible membranes, protected by a hard plastic layer), changing their shape. When done, the user tightens the screws on each side of the frame and cuts off the syringes and tubing – transforming the Adspecs into a normal pair of glasses.
Components: Plastic tubing, aluminum rings, silicone fluid, polyester thin film, polycarbonate covers
CVDW has also developed (in partnership with Dow Corning) a version of Adspecs specifically for children aged 12-18.
Support:Minimal support is likely to be required, as Adspecs were designed to be simple to distribute and use. However, Centre for Vision in the Developing World and Vision 2020 are available to provide technical assistance to organizations deploying Adspecs.
Not specified, likely because they are still in early stages of commercialization.
Professor Silver sought to develop glasses in which the optical power of the lenses could be adjusted by the individual user, thus bypassing the need for a prescription from a trained optometrist. Professor Silver has also set the target manufacturing price of a pair of Adspecs at $1 USD.
A World Bank-funded research study of students aged 12-17 years found that 90 percent of students were able to use self-adjustable glasses to correct nearsightedness (with the assistance of teachers). This is compared with nearly 100 percent of those who received professional eye exams.^(5)
Field research (Optometric Science Research Group,Department of Optometry) of Adspecs users has shown that, provided the correct fogging protocol is used, the Adspec liquid-ﬁlled lens is a good method of both determining and correcting refractive error.^(4)
Adspecs are unable to correct for astigmatism.
Smith, et al [“Spectacle lenses designed to reduce progression of myopia: 12-month results.“] Optom. Vis. Sci. 87 (2010)
Douali, M. G. and Silver, J. D. [“Self-optimised Vision Correction with Adaptive Spectacle Lenses in Developing Countries.“] Ophthalmic and Physiological Optics, 24 (2004)
Silver et al, “How to Use an Adaptive Optical Approach to Correct Vision Globally” S. Afr. Optom. 62 (2003)
Carlson, AS. [“Vision Correction in the remote North of Ghana using the self-refraction AdspecTM.”](2006)
Additionally the articles listed below are the result of a World Bank funded clinical study, which found self-adjustable glasses to be reliable and effective; validating their use for children aged 12 and over.
He, M., Congdon, N., et al [“The Child Self-Refraction Study: Results from Urban Chinese Children in Guangzhou.“] Ophthalmology, 118.6 (2011)
Zhang, M., R. Zhang, M. He, et al, [“Self Correction of Refractive Error among Young People in Rural China: Results of Cross Sectional Investigation.“] BMJ, 343.7820 (2011)
International Organization for Standardization (ISO) offers relevant standards in ISO 21987:2009, Ophthalmic optics — Mounted spectacle lenses. This is not referenced by CVDW.
[Comparison] of refractive power measurements (obtained by optometrists vs self-optimised using Adspecs)
Currently available self-refraction technology and products cannot correct astigmatism (where the amount of de-focus varies depending on the rotational axis). They are designed to correct for myopia between 0 and -5D
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