Researchers at MIT's Media Lab have developed a simple, inexpensive cell phone attachment that could offer a cost-effective solution for performing vision tests in developing countries. According to a release:
In its simplest form, the test can be carried out using a small, plastic device clipped onto the front of a cellphone’s screen. The patient looks into a 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 software loaded onto the phone provides the prescription data.
The device currently costs about $1 to $2 to produce, but researchers say the price could drop considerably if it was manufactured in large quantities. Results from preliminary tests showed the cell phone-based system was comparable to a more expensive system called an aberrometer that shines a laser into the eye and uses an array of tiny lenses to measure its characteristics.