NETRA is a mobile eye diagnostic device developed at MIT Media Lab consisting of a clip-on eyepiece and a software app for smart phones. The co-inventors include Ramesh Raskar and Vitor Pamplona. It can be seen as the inverse of expensive Shack-Hartmann sensors. NETRA allows for the early, low-cost diagnosis of the most common refractive Refractive Disorders. The subject looks into the device and aligns patterns on the display. By repeating this procedure for eight meridians, the required refractive correction is computed. NETRA exploits the fact that aberrations are expressed using only a few parameters (Spherical, Cylindrical and Axis of Astigmatism) to create an easier user interaction approach. Leveraging mobile connectivity, the system can transmit test data to appropriate facilities