Computer vision syndrome
Computer vision syndrome or CVS is when someone's sight goes blurry because they have been looking at a computer screen for too long.
Sometimes, simply changing a work environment to have better ergonomics is all that needs to be done to reduce eye strain and other vision problems related to CVS. In some cases, a good pair of computer eyeglasses may help someone see better at the right distance range needed for looking at a computer screen.
A way of preventing CVS is to take breaks while using computers.
References
Computers
Vision