What is the Computer Vision Syndrome?

Most people who work constantly with computers tend to have some or all of the following symptoms – eyestrain, eye fatigue, dry eyes, light sensitivity, blurred vision, loss of focus, double vision, headaches, and neck and shoulder pains. This symptom complex has been termed the computer vision syndrome (CVS).

What causes this problem?

CVS is caused by our eyes and brain reacting differently to characters on the screen than they do to printed characters, which are usually dense black characters with well-defined edges. Healthy eyes can easily maintain focus on the printed page. Characters on a computer screen, however, don’t have this contrast or well-defined edges. These characters (pixels) are brightest at the center and diminish in intensity toward their edges. This makes it very difficult for our eyes to maintain prolonged focus on these images. Instead our eyes drift out to a point called the “resting point of accommodation”, and then strain to regain focus on the screen. This continuous flexing of the eyes’ focusing muscles creates fatigue and the burning, tired-eyes feeling.

What can I do about it?

The solution is to see a doctor who understands CVS and its treatment. Since a computer is usually viewed from a different distance (18″-28″) than that for reading distance (16″-21″), your doctor can prescribe computer eyeglasses that will allow you to work comfortably and productively. These help by eliminating the constant refocusing effort that your eyes will otherwise perform. Place the computer terminal below the level of your eyes, so that you look down at it. Looking up at the screen causes your upper lid to lift and exposes more of the ocular surface to the drying effects of a low humidity air-conditioned environment. Concentrating on the screen is often associated with a reduced blink rate, and decreased comfort. Constant, conscious blinking when working on computers can therefore help. Another useful thing to remember is the 20-20-20 rule. Every 20 minutes, one should look away from the screen into the distance (20 feet), for 20 seconds to rest the eye muscles.

Will glare screens help?

Glare screen filters may help somewhat, but they will not solve your computer vision problems because they only affect glare from the computer screen — not the visual problems related to the constant refocusing of your eyes when working at a computer. Only when your eyes can focus clearly at the plane of proper distance on the computer screen can they experience relief from the fatiguing effects of CVS. An anti-reflective coating (AR) is also highly recommended on all computer eyeglasses. An AR coating prevents glare and reflections on the front and the back of the lenses that would interfere with focusing on the screen.

How can CVS be treated?

Your doctor will need to perform a complete eye exam to determine the various factors that may be responsible for the CVS in your case. This will include an estimation of your vision and refractive error, and the need for glasses for the distance at which you view the monitor. If the ability of the eyes to move towards each other (convergence) is less, or the tone of the muscles inside the eye that allow the lens to change shape (accommodation), is reduced, then these need to be treated. The health of the lids and the tear film is also important and needs to be assessed. The work environment and the design ergonomics of the desk and chair will also need to be determined. Based on the above, your doctor would be able to help by providing the appropriate correction – glasses, eye exercises, suggestions about your work environment and posture, and help monitor your condition.

General information

CVS has multiple causes, and these suggestions are intended to increase your working comfort – working distance from eye to screen should be set between 20″ and 26″, viewing angle for the screen should be 10 degrees to 15 degrees below straight-ahead gaze position, room lighting should be free of glare, place computer screens at 90 degrees angles to windows whenever possible, reduce room lighting so that screen brightness and contrast can also be reduced to more comfortable levels.