Working on a computer can cause eye strain, blurred vision, and symptoms of Computer Vision Syndrome. Studies show that between 50 and 90 percent of people who use computers at work have CVS.
Common causes of eye strain
For people who are under 40 years old, the most common cause of eye strain when working on computers is problems focusing. The eye functions by automatically changing focus when we look from one object to another. This is called “accommodation”. But your eyes may have trouble focusing back and forth repeatedly from the keyboard to the computer screen or from paperwork by the screen. The longer you spend on the computer, the more difficulty with accommodation your eyes may have. Another problem can be difficulty remaining focused on the computer screen for long periods of time. Looking across the room or down a hallway can help give your eyes a break from up-close focusing.
For people who are over 40, presbyopia can result in problems seeing the computer screen clearly. Presbyopia is the normal, age-related change in vision that makes it harder to see up close. It’s the condition that may cause you to hold a newspaper farther away to read it, and may require “reading glasses” for up-close work.
Why regular glasses don’t work
It may seem logical that if you need to wear glasses to read printed material, those same glasses can help you see the computer. In general, this is not the case. A computer screen is typically located about twice the distance as you would hold normal reading material. So glasses that help you read a book won’t help you focus at the correct distance to see the computer. At the same time, distance glasses are designed to help you focus farther away than the computer screen. These glasses are the kind most often needed by younger people and may be required for safe driving.
Even progressive trifocals that have prescriptions for reading, distance, and in-between are not a good choice for computer use. In a standard tri-focal, the reading portion of the lens is at the bottom. To read the computer through this part of the lens requires tilting the head back at an uncomfortable angle that will lead to neck and shoulder pain. The middle range portion of the lens is typically set to focus further away than the computer screen. This part of the lens is very narrow from top to bottom, which means only a fraction of the computer screen could be in focus at one time, even if the prescription was right for that distance.
How computer glasses can help
Computer glasses can be the solution for all these problems. Computer glasses are typically designed with single vision lenses that are specifically made to focus on the computer screen which is usually 20 to 26 inches away from the eyes. This gives a full view of the entire screen at the correct distance and can prevent neck and back strain by allowing the user to sit up straight rather than leaning into the monitor to try to see better. Some computer glasses are also made with special, occupational progressive lenses. These glasses have portions of the lens for reading up close, intermediate for the computer screen, and possibly a small portion for longer distances. The larger portion of the lens is used for the intermediate prescription for the computer screen, which makes them unsuited for use as every-day glasses or as driving glasses.
Computer glasses that have an anti-glare or anti-reflective coating can also ease eye strain by limiting glare from windows and other bright light sources. Some eye doctors also recommend a light colored tint on the lenses to reduce glare.
If you spend a lot of time on the computer, you could benefit by talking to your eye doctor about computer glasses. Before your appointment, measure the distance from the bridge of your nose to your computer monitor so your doctor can test your vision at that distance to see what correction would be best for your eyes.