Traditional eye exams require specialized equipment that is expensive to purchase and can only be operated by trained medical personnel. A new device that is currently under development may soon offer an easier and cheaper way to conduct an eye exam that could make eye exams available throughout the developing world.
Current science uses one of two methods to determine what prescription is needed to correct nearsightedness, farsightedness, or astigmatism In one method, the patient looks through a special device called a phoropter while the eye doctor tries out various lenses until the best combination is found to provide clear vision. An even more expensive method uses an aberrometer to shine a laser beam into the eye. Tiny lenses inside the machine measure the correction needed by the eye without the patient having to decide which lens provides clearer vision.
Both of these methods require expensive equipment as well as specialized training to use the equipment. In developed countries such as the United States, these kinds of eye exams are readily available and are often covered by insurance. For people in developing countries that lack higher levels of technology, eye exams are not available or are too expensive. As a result, the World Health Organization estimates that problems with vision that could be corrected with glasses are the second highest cause of blindness in the world.
MIT’s Media Lab is working to simplify the test procedure and lower the cost. They have developed a device which is being patented under the name NETRA (Near-Eye Tool for Refractive Assessment). The most basic version of their NETRA includes a small plastic eyepiece that is clipped over the front of the screen on a cell phone. The patient looks into a small lens and uses the arrow keys on the phone to line up parallel sets of red and green lines in the display. This is done several times for each eye with the lines at different angles. The test takes about two minutes to complete. Software in the phone provides the eyeglass prescription for each eye.
The project creators say the key thing that separates NETRA from previous efforts is that there are no moving parts, such as the lenses on the phoropter. Technological developments including recent improvements in digital displays and the availability of cellphones around the world combined to make this device possible. Researchers estimate that if the small device that attaches to the cellphone screen could be produced in bulk, each one would cost less than one dollar. The software was based on software written to produce tiny barcodes.
NETRA will be field-tested in Boston this summer and will then be tested in developing countries. Researchers hope it will bring new opportunities for clear vision through glasses for people who do not currently have access to eye doctors or eye exams.