"You can think of this device as a thermometer for your eye. It will measure what is wrong with your eyes, and then you might provide that data to a doctor who will provide glasses," Ramesh Raskar, associate professor of MIT Media Lab, said.
The patient looks through a four-dimensional eyepiece that clips onto the cell phone's screen. She uses the arrow keys to move sets of parallel green and red lines until they overlap.
"The number of steps it takes for the patient to align the lines indicates to us nearsightedness, farsightedness or astigmatism," Raskar explained.
Those refractive errors are the second-leading cause of blindness, affecting two-billion people worldwide. The eyepiece costs two dollars and requires no expertise compared to the bulky, expensive equipment in most optometrists' offices.
"You can see this being distributed to people where they can reach thousands and thousands of people who will not otherwise have access to any kind of eye care whatsoever," Belinda Vandervoort, a NETRA tester, said.
Taya Leary had Lasik surgery, so she has vision check-ups three to four times a year.
"It, personally, would save me the time and frustration of going to the doctor's office as well as it helps me stay on top of my sight," said Leary.
A low-cost, low-maintenance device that could change the way the world sees.