Scientists have developed an iPhone app that can give cheap, accurate prescriptions for glasses. The Near-Eye Tool for Refractive Assessment (NETRA) works in a radically different way than conventional eye tests to diagnose the exact prescription someone will need in a matter of minutes.
The patient uses the phone's buttons to adjust the position of sets of parallel green and red lines until they overlap. Instead of just estimating which of two views is less blurry the user adjusts their own display to make a scene come into focus. The more the buttons are pressed, the worse the person’s eyesight. This test is performed eight times for each eye, then it analyzes the results and delivers a prescription within minutes. The system is even able to measure other abnormalities, such as astigmatism.
The app could drastically slash the cost of eye tests.
Patients tests their eyesight by staring into a small, cheap plastic lens which fits over the iPhone’s screen. The scientists say that even though the plastic attachment will cost around a dollar at first, it could be far cheaper if produced in bulk.