PLAN 76: Article
Sight Analysis, Simplified

Media Lab Invention Holds Vision Promise for Two Billion

Researchers at the Media Lab have developed a mobile phone application that can help determine a user’s eyeglass prescription data in the field in just two minutes at little cost.

Uncorrected errors of the eye – such as nearsightedness, farsightedness, astigmatism and age-related vision loss – are the world's second-highest cause of blindness, and according to the World Health Organization, two billion people have such refractive errors, all of whom are potential beneficiaries of the new system.

The idea won a prize this year in MIT's IDEAS competition — an annual contest for inventions that hold potential for significant impact in the developing world — and made it to the semi-finals in MIT’s $100K Business Plan Competition. The team has already applied for a patent on the system, named NETRA (Near-Eye Tool for Refractive Assessment).

The technology takes advantage of recent improvements in the resolution of digital displays and their widespread proliferation on cellphones, even in some of the world's poorest countries. At a cost of only $1 to $2 today – a cost that could be reduced to just a few cents each in large quantities – the device holds enormous promise for use in the developing world.

Traditionally, eye prescriptions are diagnosed with a phoropter, a bulky case of lenses that are swung in front of each eye in various combinations, or with a high-tech aberrometer that uses a Shack-Hartman sensor to shine a laser into the eye to measure its characteristics. But the new approach, using the dual of a Shack-Hartman sensor and replacing the laser with simple user interaction, is a much quicker, simpler and cheaper way to get the same data — a method that is especially suitable for remote, developing-world locations that lack these expensive systems.

In its simplest form, the test can be done with a small, plastic device clipped onto a cellphone screen. Rather than estimating which of two views looks sharper, as in conventional eye tests, the user looks into a small lens and presses the phone's arrow keys until sets of parallel lines overlap, corresponding to bringing the view into sharp focus. The process is repeated eight times for each eye, with the lines at different angles, forcing the user to focus at different depths. The whole process takes less than two minutes, at which point software loaded onto the phone provides the prescription data.

Preliminary testing with about 20 people, and objective tests using camera lenses, have shown the device can achieve results comparable to the standard aberrometer test. The team is field-testing the device in the Boston area this summer and will later test it in developing countries.

The invention is described in a paper by Associate Professor Ramesh Raskar, head of the Media Lab’s Camera Culture Group, with Visiting Professor Manuel Oliveira, MAS student Vitor Pamplona (lead author) and research associate Ankit Mohan; the paper will be presented in late July at the annual computer-graphics conference SIGGRAPH.

The group plans to launch production of the device as a for-profit company called PerfectSight, initially targeting parts of Africa and Asia. Ultimately, they also hope to produce a more advanced version that can incorporate its own higher-resolution display and be able to detect other conditions such as cataracts, which could be sold in the developed world as well.

View a video here. For more information, visit: http://eyenetra.com.