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Research Outline

The Centre for Vision in the Developing World is a research centre that has been established with the intent of performing research to develop, support and refine efforts to provide vision correction to the developing world. We also perform basic research on vision, in the first instance by making use of the techniques and technology available to us, such as adjustable lens technology and the process of self-refraction.

At present we are primarily concerned with two projects, both related to the process of self-refraction. The first is our study, supported by the World Bank, of the applicability of self-refraction to children, and is being performed in collaboration with our partners in Boston and China. Our other project involves the creation of instrumentation to study better what happens when an individual performs self-refraction and so help us to refine this process.

Our research goals can be collected together under the following themes:

Determining the extent of the problem

Simple estimates show that the scale of the problem of uncorrected refractive error is very large, of the order of 1-2 billion people. Unfortunately, the epidemiological data is sparse and lacks detail for many locations. Nevertheless, it is well known that there are large differences of incidence of refractive error in different populations.

The consequence of refractive error is reduced visual acuity, and the practical effect of this is a reduction in an individual's ability to carry out various tasks. It is perhaps surprising that there is limited work relating refractive error and visual acuity to the performance of various functions, including driving, manual labour, close manual work, reading, writing and education. A better understanding of the effect of reduced visual acuity is essential if one is to characterise properly the extent of the problems caused by refractive error, as well as determine the levels of correction that are satisfactory for different end users.

Knowledge of the distribution of uncorrected refractive error and its consequences is important both for guiding deployment efforts and to illustrate effectively the scale and nature of the problem for government agencies, NGOs and the World Health Organization.

Refractive error and self-refraction

Much of our work to date has been based on the use of self-adjustable variable power eyeglasses (also known as adaptive eyewear or adaptive eyeglasses) as a means for an individual to determine the optimum level of vision correction that they require. A necessary part of this work has been to determine the accuracy of our self-refraction process when compared to conventional methods. Such comparisons are ideally made using the best available techniques; a so-called gold standard. However, it is not clear that a good gold standard for measuring refractive error exists. Standard instruments, such as autorefractors, produce accuracy comparable to self-refraction, and we have published work demonstrating less than ideal reproducibility between optometrist performed measurements.

We envisage further research to improve our understanding of the relationship between refractive error, visual acuity and optimum correction, which likely includes a subjective component. We are also interested in conducting research into the accuracy of the vision correction being worn by people in the UK.

We are developing our own instrumentation based on adjustable lens technology so that we may perform a variety of experiments. As well as getting detailed information from self-refraction procedures, the dynamic nature of our instruments enables a variety of new experiments involving the focussing mechanisms of the eye (the accommodative system). As well as providing insight into the process of self-refraction, helping us to improve it, this work may also provide fundamental insight into the processes associated with accommodation.

Our results for self-refraction to date have been very encouraging and have given us confidence that self-refraction is a valid procedure for vision correction. At the present time we are investigating its application to teenagers as a precursor to using self-refraction with children. Meticulous ongoing research such as this is essential to demonstrate and expand the validity of self-refraction, refine its application in practice, and to address the potential concerns and objections of eyecare professionals which could otherwise create obstacles.

Correcting vision in the developing world

The work of the Centre is very much coupled to practical efforts actually deploying vision correction to the developing world. There are many ways of doing this and at the present time it is not clear what will work best in different locations. To date the deployment of self-adjustable eyeglasses has mostly been within a supervised environment. An individual is taken through a protocol intended to arrive at the optimum correction that they require. Inevitably, there is a compromise between the complexity of the protocol and the feasibility with which it may be implemented and this is a matter for research.

There are many general issues to consider related to deployment including methods of distribution, screening, fitting protocols, training, supervision, device selection and scalability. One of the roles of the Centre will be to advise and support the creation of different deployment efforts and then measure how effectively they fulfil their objectives.

The challenges associated with providing vision correction to the developing world are considerable. Our goal is to build a world class research centre capable of meeting these challenges.