In days gone by, children were often warned that reading in poor light or in awkward positions would "ruin" their eyes. Fortunately, problems rarely ensued. Not so among today's computer users; many experience preventable eye or vision problems.
With images on a computer screen fast supplanting the printed word, complaints about vision-related problems like eyestrain, blurry vision, headaches and neck aches are multiplying. Millions of people, from preschool ages on, who work or play the day away on video display terminals are suffering needlessly, experts say.
Although vision and eye problems have been overshadowed by carpal tunnel syndrome as a debilitating hazard of prolonged computer use, they are actually more common and should not be ignored. Virtually all can be corrected -- and avoided -- with proper adjustments in the work environment and the user's position in relation to the screen.
Although there is no evidence of permanent visual damage from the prolonged use of VDTs, even temporary impairments can be troublesome. The problems can occasionally be dangerous; for example, if computer use at work impairs distance vision, driving home could be hazardous.
First, the good news. Repeated tests have shown that video display terminals do not emit hazardous radiation -- neither ultraviolet nor ionizing radiation -- so even daily use for decades should not cause cataracts or retinal damage. Nor is there evidence that computer use causes permanent myopia, or nearsightedness, or speeds development of myopia any more than reading books might.
However, several surveys of people who work at video display terminals indicate that up to 75 percent experience one or more reversible vision or eye problems. The American Optometric Association has coined a name for the complaints: computer vision syndrome. Symptoms may include any or all of the following:
Temporary myopia, the inability to focus clearly on distant objects for a few minutes to a few hours after using the computer.
Eyestrain or eye fatigue, a tired, aching heaviness of the eyelids or forehead.
Blurred vision for near or far objects, and sometimes double vision or afterimages.
Dry, irritated or watery eyes.
Increased sensitivity to light.
Headaches, neck aches, backaches and muscle spasms from holding the body in awkward positions to maintain a desirable angle between eyes and screen.
Why should computer use cause such problems when reading a book or papers for hours on end rarely does? The American Academy of Ophthalmology and optometrists who study computer-related problems say several factors apply especially to computer use:
Poor position in relation to the computer.
Lighting that produces glare or reflections, fuzzy images or images that are too dim or even too bright.
Failure to blink often enough to moisten the surface of the eyes.
Use of corrective lenses that are inappropriate for the user's position and distance from the screen.
Minor visual defects that might go unnoticed if not exaggerated by intense computer use.
For example, Dr. Kent M. Daum, an optometrist at the University of Alabama School of Optometry in Birmingham, showed that minor and otherwise unnoticed refractive errors, astigmatisms or imbalances between the eyes can cause pronounced discomfort after as little as half an hour at the computer. He showed that correcting such problems with properly fitted lenses could noticeably increase comfort.
With regard to dry, irritated eyes, Dr. James Sheedy, a clinical professor of optometry at the University of California at Berkeley, cited a Japanese study of how often people blink.
When people converse, they blink, on average, 22 times a minute; when they read, they blink 10 times a minute, but when they use a VDT, that drops to seven times a minute. In addition, Sheedy said, people generally look down when they read but stare straight ahead at a screen, so eyes are open wider and are subject to more evaporation.
As for aching necks and backs, Sheedy explained that people naturally try to look down at a computer screen at an angle of 10 to 20 degrees. If the screen is at or above eye level, the tendency is to tilt the head back, and that can cause stiff necks and backaches.
People who wear bifocals or progressive (variable focus) lenses are forced to tilt their heads back to see the screen at all. Even with a head tilt, the image is not as clear as it could be because the prescription typically issued for a reading lens is adjusted for an eye-to-page distance of 16 inches at an angle of 25 degrees. Computer screens are usually 20 to 24 inches away at a tilt of 10 to 15 degrees.
Anyone who spends a significant amount of time at a computer terminal would be wise to start with a thorough eye examination. Any visual defects should be corrected with lenses prescribed especially for the computer.
If you do not have to see distant objects clearly while at the computer, a bifocal lens with the top adjusted for the computer screen and the bottom for reading is ideal. Or a lens entirely adjusted for the computer screen might be used, and paper work could be held at the same distance as the screen.
If distant vision must be clear while working at the computer, a bifocal lens with the upper part adjusted for distance and a large bottom section for the computer is recommended. Or a progressive lens with a large middle section for computer work could be used.
When sitting at the computer, adjust your seat or the computer work station so that the center of the screen is four to nine inches below eye level and a little farther away than the normal reading distance. Keep reference material close to the screen, perhaps on a screen mount.
Wipe the screen often with an anti-static cloth. To minimize glare, put the computer at right angles to windows, or use blinds or an awning. If possible, reduce the brightness of room lighting or use a three-sided computer hood or a micromesh screen filter.
Periodic rest breaks are crucial. Every 15 minutes or so, look up and focus on distant objects for about 2 minutes. While you are at it, do some stretching exercises to relieve tension in your neck and back. Frequent blinking and using saline eye drops can reduce dryness and irritation.
Daum warned: "Don't wait until the signs on the Interstate don't look right before you see an eye-care specialist. If you're sitting at a computer and your eyes hurt, have your prescription checked."
Sheedy added, "Make sure your optometrist or ophthalmologist knows that you use a computer regularly."
Pub Date: 8/13/96