There are new applications and functions available for smartphones by the day. When I heard that there was now a way to use a smartphone to measure refractive error I assumed this was some form of hoax or perhaps a novelty marketing tool. It is anything but.
A team at MIT Media Lab, a research group with a long track record of developing photographic and optical innovations, have produced an attachment which fits over most large screen smartphones and allows the viewer to undertake a simple two-minute test which then arrives at an estimation of their refractive error. The main interest for this development is likely to be developing countries where access to more expensive refractive assessment, either optometry-led or through autorefractor or aberrometer, may be restricted. As each device costs around $2 and many mobile phones are available throughout the world, the device offers an inexpensive way to measure refractive errors.
The device, when activated, projects two parallel lines onto the screen which are viewed from a close distance. The viewer uses the key pad to reduce the distance between the two lines until they overlap. This is done for lines at nine different orientations, at the end of which the software is able to calculate the spherical and cylindrical component of the refractive error. Early trials using the Apple iPhone 4G have found a margin of error of less than 0.50 dioptres for both sphere and cylinder and a tolerance of within 6 degrees for axes. Accommodation fluctuation is, however, a potential source of significant error. While this is not to be viewed as a replacement for optometric assessment in any way at all, it is to be welcomed as a simple means of allowing untrained workers in the most remote parts of the world to assess refractive error for later correction with spectacles with a respectable degree of accuracy.
'Our device has the potential to make routine refractive eye exams simpler and cheaper, and, therefore, more accessible to millions of people in developing countries,' says MIT's visiting professor Manuel Oliveira. Research associate Ankit Mohan, who worked on the paper, says: 'People have tried all kinds of things, some very clever as possible replacements for the heavy and expensive conventional eye-testing systems. The key thing that differentiates ours is that it doesn't require any moving parts.'
It will be interesting to see how the device is taken up globally. ?