It is estimated that about one billion people in the Developing World would benefit immediately from distance vision and near vision correction if it were available to them. Here we address this problem by correcting vision in the field with adaptive liquid filled variable focus lenses, and test whether it is possible by simple means to determine and obtain correct refraction using such lenses.

It is estimated by the World Health Organization that about 1 billion people in the developing world would benefit immediately from distance vision and near vision correction if it were available to them. Here we address this problem and provide a solution by correcting vision in the field with adaptive liquid-filled variable focus lenses. We describe the details of the lens and present the results of a series of experiments performed in Ghana, Nepal, Malawi and South Africa that demonstrate that it is possible by simple means to self-determine and obtain correct refraction using such lenses.