Blindness is often perceived as a permanent medical condition, untreatable without highly advanced medical intervention. However, millions of blindness cases result from uncorrected refractive error – a condition that can be easily treated with prescription eyeglasses. Over 90% of these cases are in the developing world7, and remain untreated due to lack of access to corrective eyewear. This is true not only for blindness, but for all severity levels of vision impairment, making refractive error the leading untreated ophthalmic medical condition4. At present, 1 billion people in the world suffer from vision impairment and lack access to corrective eyewear.
Beyond the detrimental effects on the quality of life on the individual level, untreated vision impairment has substantial societal and economic consequences, including academic underperformance and reduced literacy, reduced workplace productivity, decrease in road safety, and gender inequality. At present, these result in an annual global financial loss of $410 billion, which, due to population growth, is predicted to increase to $920 billion by 2050 – a $20 trillion loss over three decades.
While in the developed world optometry services, which include diagnosis, prescription, and lens fabrication, are widely accessible, they are scarce in the developing world. For example, there are 221 optometrists per 1M people in high income countries (Europe, North America) but only 1 optometrist per 1M people in sub-Saharan Africa. While much work has been done in the past decade in developing accessible solutions for hdiagnosis and prescription, there remains a major challenge in providing individuals with appropriate eyeglasses.
The standard methods for fabrication of eyeglasses are based on mechanical processes such as machining and polishing, or molding. These processes require significant energy and water resources, major capital investments in infrastructure, and operation by trained personnel. Such facilities are incompatible with low-resource settings, and thus attempts to satisfy the demand for eyeglasses in such regions have relied primarily on operating distribution logistics to deliver pre-fabricated lenses to the point of need7. To date, according to the World Economic Forum, all such initiatives were able to supply only a small fraction (0.3% in 2016) of the need. Given these circumstances, there is a pressing need to innovate lens manufacturing methodologies. For example, new technologies, which bring fabrication of high-quality eyeglasses close to the point-of-need, and that are appropriate for low-resource settings, have the potential of disrupting the existing modes of operation and providing a larger fraction of the population with access to corrective eyewear.
In our work we leverage the Fluidic Shaping approach to create a complete solution for fabrication of prescription lenses that eliminates the need for any machining, polishing, or molding steps. Using a device whose footprint is 20 cm x 20 cm, with an energy consumption of 25 W, a pair of high-quality lenses (diopter variation of less than 0.15 D, and surface roughness of less than 1 nm) can be produced in under 10 minutes. As illustrated in Figure 2, the entire lens fabrication process takes place within a single device that transforms a volume of liquid polymer into a lens with any combination of spherical or cylindrical corrections.
