New research shows that people reading text messages or browsing the Internet on their smart phones tend to hold the devices closer than they would a book or newspaper, forcing their eyes to work harder than usual.
When reading printed text in newspapers, books and magazines, the average working distance is 16 inches from the eyes. However, the study participants on average held their smart phones only about 14 inches away. For some people, it was as close as 7 inches.
Doctors say this can result in headaches, eye strain, dry eye, and blurred vision after prolonged use.
The study appears in the July issue of Optometry and Vision Science.