Source:allaboutvision
Presbyopia usually occurs beginning at around age 40, when people experience blurred near vision when reading, sewing or working at the computer.
You can't escape presbyopia, even if you've never had a vision problem before. Even people who are nearsighted will notice that their near vision blurs when they wear their usual eyeglasses or contact lenses to correct distance vision.
Presbyopia is widespread in the United States. According to U.S. Census Bureau data, over 135 million Americans were age 40 and older in 2008, and the country is growing older: The median age reached 36.8 in 2008, up 1.5 years since 2000. This growing number of older citizens generates a huge demand for eyewear, contact lenses and surgery that can help presbyopes deal with their failing near vision.