A team at MIT has created a simple, inexpensive eye test using a cell phone. Software in the cell phone works in conjunction with an eye piece attachment.
If you?ve ever squinted through a phoropter while the optometrist switches lenses and demands that you decide which one makes the letters clearer, you can appreciate the new method. It does not rely on your ability to discern between blurry letters and sharp characters.
Netra system: Eye Exam using mobile phonesUsing the recently publicized Netra system, all you need to do is look into the eye piece clipped to your cell phone and make two green lines overlap. You accomplish this by using the arrow keys on the cell phone. When the images line up, your visual ability is determined, and a prescription can be written from the results. 

The system is safer than other methods in that it does not use lasers, and doesn?t need cycloplegic drugs, which paralyze the muscles of the eye during the exam. The combined cell phone and software shows promise for testing eyesight in developing countries where a phoropter is impractical, and optometrists are hard to come by. It makes testing accessible and easy.

The Netra eye test method resulted from a system to develop small bar codes, called bokode, which are imperceptible visual tags for camera-based interaction from a distance. They were created to replace optical tags, that must be read at short range, such as the scanning we are familiar with at the check out stand. The current sized codes take up valuable space on produce packaging that could be used for advertising, product recognition, and instructions on use.

The bokodes can be used to determine if a person has a refractive error. As Ankit Mohan, one of the MIT researchers says: "People have tried all kinds of things, some very clever. What?s really great about our technique is that it contains no moving parts, all the intelligence is in the software and we can make it very cheap and simple."

You might not see the Netra at your local optometrist?s office soon, but inhabitants in remote areas of developing countries may see an improvement in eye care in the near future.