MIT’s Ramesh Raskar holding the Netra device. (John Werner/Camera Culture Group)
MIT’s Netra, a plastic, binocular-like headset attaches in the front to a smartphone. Users peer through the headset at the phone’s display. Patterns, such as separate red and green lines or circles, appear on the screen. The user turns a dial to align the patterns and pushes a button to lock them in place. After eight interactions, the app calculates the difference between what the user sees as “aligned” and the actual alignment of the patterns. This signals any refractive errors, such as nearsightedness, farsightedness, and astigmatism. The app then displays the refractive powers, axis of astigmatism, and pupillary distance required for eyeglasses prescriptions.

The technology is being considered for integration into virtual-reality displays to develop custom screens to fit a user’s eyeglass prescription. Prescription screens could make virtual-reality devices more form-fitting for a more immersive and comfortable experience. But it could also help solve a larger issue: aligning the eye lens, prescription lens, and the virtual-reality screen.