"There isn't a name for it and few eye doctors test for it. But many people are having trouble seeing in the middle distance that demands so much of our focus. Some 80% of us use computers, staring intently on screens set well between typical distance and reading range, often for many hours each day. Add in laptops, pagers, e-readers, smartphones, personal-digital assistants and hand-held video games, each with its own optimum..."