Measuring someone for eyeglasses normally requires expensive, bulky equipment that isn’t easily transported. The researchers at the MIT Media Lab have developed a simple $1 piece of plastic that when attached to a smartphone, functions as a diagnostic instrument. In underdeveloped countries, eye care is very often a luxury for most citizens. That’s why Ramesh Raskar and Manuel Oliveira, two professors at the Media Lab along with post-doc Ankit Mohan created the Near-Eye Tool for Refractive Assessment, or NETRA
NETRA is as simple as a patient peering into a small lens attached to a smartphone. This smartphone must have the corresponding application that is equipped with the testing feature. On screen, the patient sees parallel red and green lines. The patient is instructed to use arrow keys on the phone to adjust those lines until they overlap. This test is extremely quick and after just two minutes of testing, the application produces the proper eyeglass prescription based off the test results. The way the test works, someone with 20/20 eyesight would be able to correctly overlap the lines which would only appear blurry. However, to someone with less than perfect sight, the lines would appear separated, skewing their test results. The application then reads how far off the patient’s results are and fits them for the ideal lens strength.
With this system, a patient doesn’t need lenses to bring a blurry image into focus, contrary to typical diagnostic instruments and machines that optometrists more commonly use. Instead, the smartphone attachment uses a basic system of lenses and pinholes.