Joshua Silver, Centre for Vision in the Developing World
Adspecs are self-adjustable eyeglasses made for the rural population.
Adspecs are self-adjustable eyeglasses which allow users to set the right focus for each lens. The pair of lenses work on the principle of making the lens to go from convex to concave with the application of fluid-filled syringes. The syringes transfer the fluid in between the bi-layer of the lens and set the focal length.
Centre for Vision in the Developing World (CVDW) partnered with government and community organizations for trials.
19 USD per pair
Goal 3: Good health and well-being
People in developing countries requiring vision aids who do not have access to a trained optometrist to obtain prescription glasses.
The glasses are constructed using plastic tubing, aluminum rings, silicone fluid, polyester thin film, polycarbonate covers. The adjusters allow the user to adjust the fluid in the lenses to get the right amount of correction. The glasses are made so the adjusters can be locked or removed after the amount of correction is set.
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.
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 CVDW has also developed (in partnership with Dow Corning) a different version of Adspecs specifically for children aged 12-18.
Centre for Vision in the Developing World (CVDW) and Global Vision 2020 provides training to teachers to supervise the adjusting process.
Centre for Vision in the Developing world ran clinical trials and found that 95% of subjects were able to properly adjust the glasses.
A World Bank-funded research study of students aged 12-17 years found that 90% 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.
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.
Centre for Vision in the Developing World (CVDW)
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
Sankaridurg, P., Donovan, L., Varnas, S., Ho, A., Chen, X., Martinez, A., … & Holden, B. (2010). Spectacle lenses designed to reduce progression of myopia: 12-month results. Optometry and vision science: official publication of the American Academy of Optometry, 87(9), 631.
Douali, M. G., & Silver, J. D. (2004). Self-optimized vision correction with adaptive spectacle lenses in developing countries. Ophthalmic and Physiological Optics, 24(3), 234-241.
Silver, J. D., Douali, M. G., Carlson, A. S., & Jenkin, L. (2010). How to use an adaptive optical approach to correct vision globally. South African Optometrist, 62(3), 126-131.
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., MacKenzie, G., Zeng, Y., Silver, J. D., & Ellwein, L. (2011). The child self-refraction study: results from urban Chinese children in Guangzhou. Ophthalmology, 118(6), 1162-1169.
Zhang, M., Zhang, R., He, M., Liang, W., Li, X., She, L., … & Moore, B. (2011). Self correction of refractive error among young people in rural China: results of cross sectional investigation. Bmj, 343, d4767.
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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