Computer vision syndrome (CVS) or digital eye strain, can affect anyone who spends three or more hours a day in front of a computer, tablet, e-reader or cell phone. Many individuals are at risk, including those who “cannot work without a computer.” And that’s not counting the millions of children, adolescents and adults who spend many hours a day playing screen-based games or using e-readers. The average American worker spends seven hours a day on the computer, either in the office or working from home.
The most common symptoms associated with CVS are:
The level of discomfort appears to increase with the amount of digital screen use. Symptoms may be caused by:
One reason the problem is so pervasive is that words printed on a page have sharply defined edges, electronic characters, which are made up of pixels, have blurred edges, making it more difficult for eyes to maintain focus. Unconsciously, the eyes repeatedly attempt to rest by shifting their focus to an area behind the screen, and this constant switch between screen and relaxation point creates eyestrain and fatigue.
Another unconscious effect is a greatly reduced frequency of blinking, which can result in dry, irritated eyes.
The head’s distance from the screen and position in relation to it are also important risk factors. To give the eyes a comfortable focusing distance, the screen should be about 20 to 26 inches away from the face. The closer the eyes are to the monitor, the harder they have to work to accommodate to it. In addition, when looking straight ahead, the eyes should be at the level of the top of the monitor. The University of Pennsylvania’s ophthalmology department advises that the center of the monitor should be about four to eight inches lower than the eyes to minimize dryness and itching by lessening the exposed surface of the eyes because they are not opened wide. This distance also allows the neck to remain in a more relaxed position.
Improper lighting and glare are another problem. Contrast is critical, best achieved with black writing on a white screen. The screen should be brighter than the ambient light — overly bright overhead light and streaming daylight force the eyes to strain to see what is on the screen. A bright monitor also causes your pupils to constrict, giving the eyes a greater range of focus.
You might need to reposition the desk, use a dimmer switch on overhead lights, or lower window shades to keep out sunlight. In addition, using a flat screen with an antiglare cover, and wearing glare-reducing or tinted lenses can help to minimize glare. Be sure to use a font size best suited to your visual acuity, and have your eyes examined regularly — at least once a year — to be sure your prescription is up-to-date. This is especially important for people older than 40 and for children who are heavy users of computers because visual acuity can change with age. Make sure, too, that your monitor has a high-resolution display that provides sharper type and crisper images. And clean the monitor often with an antistatic dust cloth.
While prevention is most important, if you already have symptoms of computer vision syndrome, there are ways to reduce or eliminate them. Ophthalmologists suggest adhering to the “20-20-20” rule: Every 20 minutes, take a 20-second break and look at something 20 feet away. Consciously blink as often as possible to keep eye surfaces well lubricated. To further counter dryness, redness and painful irritation, use lubricating eye drops several times a day.
You can also reduce the risk of dry eyes by keeping air from blowing in your face, by using a humidifier, and applying a warm moist compress to the eyes every morning. Solutions to CVS problems are varied. However, they can usually be alleviated by obtaining regular eye care and making changes in how you view screens.
By Rebecca Richmond, COT and Robert Castrovinci, MD
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