MIT’s Media Lab team devises NETRA eyesight testing with phones
Posted on June 25th, 2010 | Filed under: General
A team from MIT’s Media Lab has come up with an innovative technology using phones that procures similar results for eye-testing to those obtained using phoropter or aberrometer. The device has been described in a paper by MIT Media Lab Associate Professor Ramesh Raskar, Visiting Professor Manuel Oliveira, Media Lab student Vitor Pamplona (the lead author of the paper), postdoctoral research associate Ankit Mohan and IT consultant Margaret McKenna also supports the team.
The paper will be presented in late July at SIGGRAPH, the yearly computer-graphics conference. The eye-testing system devised by the MIT team is touted to be cheaper and quicker. The device could be beneficial to those living in remote areas and regions of the developing and underdeveloped nations.
In order to assist in commercializing the system, another member who joined the team is Chika Ekeji, a student at the MIT Sloan School of Management. Chika has stated that the group plans to get into production with PerfectSight, a profit-making organization. The company will initially be targeting parts of Africa and Asia. The team has applied for the patent rights of the system entitled, NETRA (Near-Eye Tool for Refractive Assessment).
“Our device has the potential to make routine refractive eye exams simpler and cheaper, and, therefore, more accessible to millions of people in developing countries,” states MIT’s Visiting Professor Manuel Oliveira.
The team of NETRA has created a ground-breaking system that would improve the current second highest cause of blindness. The team asserts that according to the World Health Organization, uncorrected refractive errors are the world’s second-highest cause of blindness, affecting around two percent of the world’s population. Two billion of the world population has refractive errors in their eyes.
“People have tried all kinds of things, some very clever,” as possible replacements for the heavy and expensive conventional eye-testing systems, remarks Mohan. “The key thing that differentiates ours is that it doesn’t require any moving parts.”
The NETRA system has a very innovative and fresh system of attesting the defects in the eyesight, which is completely different from the conventional means of eye-testing using phoropter or aberrometer. The phoropter is the traditional method of eye-testing, patient has to look through the device. The device is fitted with several different lenses, which are swung into place in front of each eye in a mixture of combinations. These combinations are assessed by patients as they try to read a standard eye chart placed on the opposite wall.
On the other hand, aberrometer is quite expensive and quicker, compared to the phoropter. This eye-testing method is a simpler method as it requires no involvement from the patient. The device shines a laser into the patient’s eye and then with the help of a range of tiny lenses it measures the eye’s characteristics.
This innovation in its simplest form tests the patient’s eye by utilizing a small plastic device hooked onto the front of a mobile phone’s screen. The patient has to look into a small lens and then press the handset’s arrow keys till sets of parallel green and red lines overlap. The same procedure is repeated eight times with the lines at different angles. It is carried out for each eye. The entire procedure finishes in less than two minutes, after which software integrated in the phone supplies the user with the prescription data.
The technology used to create the device benefits from the large-scale progress of the resolution of digital displays made in the past few years and the extensive proliferation of mobile phones. Other than the software embedded in the handset, all that is required is the snap-on plastic device, which according to Mohan will be manufactured at a cost of about $1 to $2 today, however would only cost a few cents once large-scale production begins.
“By using high-resolution LCD displays with this system, it is potentially not only much faster than today’s standard methods, but also potentially more accurate,” claims Raskar. However, the device’s less time consuming ability hasn’t yet been demonstrated or proven.
NETRA works on an optical system procured from a system developed by some of the team members last year. This system was devised as a means of generating minute barcodes known as Bokodes, which could supply the user with large amount of information.
Raskar elucidates that ‘he had demonstrated that barcode device to many people, but when he showed it to his wife she had trouble seeing its patterns. He quickly realized that others he had shown it to had been wearing their glasses or contact lenses, but his wife had been looking into it directly and it had revealed the imperfections in her vision.’ ‘I said, “Wow, maybe you don’t need such an expensive device” as those presently being used to test people’s vision’, he further recalls.
Raskar and his students then devised a model system based on the discoveries through that insight. The prototype system had a collection of minuscule lenses and a grid of pinholes which amalgams with the software in the handset, making the user focus on a variety of depths and eventually measuring the eye’s focusing ability.
Raskar goes on to explaining, that essentially the eye-test functions by converting any blurriness generated by aberrations in the eye into a set of separate lines or dots instead of an unclear spot that makes it simpler for the user to visibly make out the difference. The conventional eye tests use to judge which of the two views look sharper, however in this system the user brings the view into sharp focus by tuning in the display to make the separate lines or dots come together and overlap.
The fundamental principle is analogous to that used by new “adaptive optics” systems, which have of late enabled ground-based telescopes to augment the performance of the Hubble Space Telescope. These optics systems sometimes employ the same kind of Shack-Hartmann sensors used in eye testing aberrometers.
The first round of tests conducted on around 20 people and the objective tests using camera lenses have displayed that it can accomplish results similar to the standard aberrometer test. Thus, the team is currently preparing to conduct clinical trials. They will also be field-testing the device in Boston, this summer and then move on to testing it in developing countries.
MIT’s Media Lab team, the creators of the NETRA device look forward to invent a superior version that would hold its own higher-resolution display. A higher version of NETRA enabled with a technology that can detect conditions like cataracts and can be sold in the developed world as well.
