New Cell Phone App Determines Eyeglass Prescription Data

According to the World Health Organization, 2 billion people suffer from undiagnosed vision problems. Many of these 2 billion live in developing world, where expensive optical diagnostic equipment is unavailable. Although completely treatable given the right equipment, refractive errors – nearsightedness, farsightedness, astigmatism and age-related vision loss – are the second highest cause of blindness worldwide.

Researchers in Ramesh Raskar’s Camera Culture Group at the MIT Media Lab have developed a low-cost alternative to traditional optical diagnostic tools. NETRA (Near-Eye Tool for Refractive Assessment) is a small plastic device that clips on to a mobile phone screen. The user looks through the device to see two parallel lines on the screen, which they can align using the phone’s arrow keys. The NETRA app cycles through 8 combinations of parallel lines, each at different angles, which require the user to focus their eyes at different depths. Based on how the user aligns each set of parallel lines, the app can calculate vision prescription data, which is then displayed on the phone screen. The whole process takes less than 2 minutes to complete.

The researchers behind NETRA, Manuel Oliveira, Vitor Pamplone, Ankit Mohan, and Ramesh Raskar, are optimistic that their device holds enormous promise for the developing world. It costs only $1-$2 per unit to produce, but as production is scaled up, they believe this per-unit-cost could be decreased to just a few cents. (There is, of course, still the issue of providing low-cost corrective lenses for patients after their prescription is diagnosed…but maybe that’s part of NETRA Phase II.)

NETRA is a lightweight, inexpensive, and easy to use alternative to traditional diagnostic tools such as the phoropter (a bulky case of lenses that a patient can look through, choosing which corrective lens combination is clearer) or the aberrometer (which uses a Shack-Hartman sensor and a laser shined into the eye to measure vision characteristics). In preliminary tests, NETRA performed well, providing data comparable to that which was gathered using these more traditional methods. The research group plans to begin production of their device through a newly-formed company called PerfectSight; they are in the process of selecting initial distribution sites in Africa and Asia.