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MIT demos eye exam via handset display

Posted: 06 Jul 2010 ?? ?Print Version ?Bookmark and Share

Keywords:cellphone eye exam? software? display?

Massachusetts Institute of Technology (MIT) researchers have developed an eye exam that can be executed using a small, plastic device clipped to the front of a cellphone's screen. Preliminary tests show results comparable to the more expensive aberrometer test for eyeglass prescriptions.

A team at MIT's Media Lab has come up with the test methodology that is especially suitable for remote, developing-world locations. According to the World Health Organization, two billion people worldwide are affected with uncorrected refractive errors. This inexpensive test can be used to help people with prescription eyeglasses.

In the test, patient looks into the small lens and presses the phone's arrow keys until sets of parallel green and red lines just overlap. This is repeated eight times, with the lines at different angles, for each eye. The whole process takes less than two minutes, at which point the phone's application software provides the prescription data.

"The key thing that differentiates our [device from other methods] is that it doesn't require any moving parts," said postdoctoral research associate Ankit Mohan.

The prototype system has an array of tiny lenses and a grid of pinholes that combined with the software on the phone enables to measure the eye's focusing ability. Any blurriness produced by aberrations in the eye is transformed into an array of separate lines or dots instead of a fuzzy blob, which makes it easier for the user to identify the discrepancy clearly.

Rather than estimating which of two views looks sharper, as in conventional eye tests, the user adjusts the display to make the separate lines or dots come together and overlap, which corresponds to bringing the view into sharp focus.

Mohan said the snap-on plastic device can be produced at a cost of about $1 to $2 but could cost only a few cents in large quantities.

The MIT researchers claim that the underlying principle is similar to that used by new "adaptive optics" systems that have recently allowed ground-based telescopes to exceed the performance of the Hubble Space Telescope. The researchers plan to launch production of the device as a for-profit company called PerfectSight, initially targeting parts of Africa and Asia.

Ultimately, they also hope to produce a more advanced version that can incorporate its own higher-resolution display and be able to detect other conditions such as cataracts.

The device is described in a paper to be presented in late July at Siggraph.

- Nicolas Mokhoff
EE Times

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