Studies have found that a majority of people who work on computers or hand-held devices experience some vision problems.Many of those people need special-purpose glasses with lenses adjusted to bring the computer screen sharply into focus.computer workers blink much less frequently than they would during a face-to-face conversation, and that leads to dry eyes at work.Computer glasses can take several forms.depending on the patient's age and visual needs,For adults under 40 who have not yet experienced the normal age-related loss of near-focusing ability, called presbyopia single-vision lenses are typically used for computer glasses.For people with presbyopia, doctors often prescribe single-vision, bifocal,trifocal or progressive lenses (without lines),depending on the wearer's need.Trifocals for computer work typically have a larger-than-normal intermediate zone placed higher in the lens for more comfortable viewing of the computer screen, but they still contain a small zone in the top of the lens for distance viewing.