NETRA: Refractive Tests on a Mobile Phone
Inverse Shack-Hartmann Wavefront Sensor
using High Resolution Mobile Phone Display
| Vitor F. Pamplona* Ankit Mohan Manuel M. Oliveira* Ramesh Raskar David Schafran Erick Passos Everett Lawson Camera Culture Group - MIT Media Lab * Visiting from Instituto de Informática - UFRGS See our latest works on Cataract Mapping and tailored displays |
   OneSight's Mission Trip - Nairoby, Kenya LVPEI's Clinical Trials - Hyderabad, India |
| Figure 1: Netra is a $2 clip-on eyepiece that goes on top of a cell phone. The user looks through this eye piece and interactively aligns the displayed patterns by clicking the buttons. The number of clicks required to bring the patterns into alignment indicates the refractive error. Our optometry solution combines inexpensive optical elements and interactive software components to create a new portable and inexpensive device that mimics (and replaces) the expensive laser-based Shack-Hartmann wavefront aberrometers. Ilustration: Tiago Allen |
Abstract
We introduce a portable and inexpensive solution for estimating refractive errors in the human eye. While expensive optical devices for automatic estimation of refractive correction exist, our goal is to greatly simplify the mechanism by putting the human subject in the loop. A traditional Shack-Hartmann wavefront sensor uses lasers and highly sensitive digital sensor which makes those solutions expensive, bulky and requires trained professionals.
Our solution creates an inverse Shack-Hartmann sensor. It is based on a high-resolution programmable display and combines inexpensive optical elements, interactive GUI, and computational reconstruction. The key idea is to interface a lenticular view-dependent display with the human eye at close range - a few millimeters apart. Via this platform, we create a new range of interactivity that is extremely sensitive to parameters of the human eye, such as the refractive errors, focal range, focusing speed, lens opacity, etc. We propose several simple optical setups, verify their accuracy, precision, and validate them in a user study.