In The World: Easy on the eyes
There are two standard systems for determining a prescription for eyeglasses to correct refractive errors such as nearsightedness, farsightedness and astigmatism. One is to have the patient look through a large device called a phoropter, fitted with dozens of different lenses that can be swung into place in front of each eye in various combinations, while the patient tries to read a standard eye chart on the wall ahead. The other uses 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, with no interaction from the patient.Now, a team at MIT's Media Lab has come up with a much quicker, simpler and cheaper way to get the same information — a method that is especially suitable for remote, developing-world locations that lack these expensive systems. Two billion people have refractive errors, and according to...