All participants were asked to bring home an LED flashlight and to watch for three minutes each day 670 nanometers of deep red light emitted by the flashlight.
They found that the deep red light at 670 nanometers had no effect on the younger participants, but significantly improved in people in their 40s and older, with some seeing a 20 percent increase in the sensitivity of vertebral cells, which detect color. In addition, the sensitivity of rods was improved.
Jeffrey said the study showed that brief exposure to certain wavelengths of light, like charging a battery, can significantly improve failing vision in older people.