CVS is short for Computer vision syndrome and it is a set of vision related issues that can be caused by continuous computer usage. This is usually a temporary disorder caused by constant staring at a computer monitor for uninterrupted, protracted time periods. Many computer users experience vision issues and discomfort in their eyes when viewing a computer monitor for long periods. The degree of discomfort usually depends on the visual ability and seems to rise with the level of computer usage. According to the National Institute of Occupational Safety and Health the CVS can affect around 90% of computer users who spend three hours or more per day in front of a computer screen. Most of the visual disorder symptoms are just temporary and can diminish after ending the computer usage. Still, many people may suffer from extended reduced visual capabilities, including blurred distant vision, despite ending work at a computer.