CAMBRIDGE, Mass.—A team at MIT’s Media Lab has come up with a quick, simple and inexpensive way to perform refractions using cellphones. The method, known as NETRA (Near-Eye Tool for Refractive Assessment), is especially suitable for remote, developing-world locations that lack conventional examination instruments such as phoropters or aberrometers, according to MIT.

According to the World Health Organization, uncorrected refractive errors are the world’s second-highest cause of blindness, affecting some 2 percent of the world’s population; all these people are potential beneficiaries of the new system. The MIT team is preparing to conduct clinical trials, but preliminary testing with about 20 people, and objective tests using camera lenses, have shown that it can achieve results comparable to the standard aberrometer test.

The test can be carried out using a small, plastic device clipped onto the front of a cellphone’s screen. The patient looks into a small lens, and presses the phone’s arrow keys until sets of parallel green and red lines just overlap. This is repeated eight times, with the lines at different angles, for each eye. The process takes less than two minutes, at which point software loaded onto the phone provides the prescription data.

Go to VM WebTV at www.visionmonday.com to see videos explaining how the NETRA works. ■ ■