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BU Bridge Logo

Week of 4 December 1998

Vol. II, No. 16

Health Matters

Eye on computers: keeping your focus

My work involves many hours spent staring at a computer screen. Should I be worried about eyestrain or other eye ailments caused by my computer screen?

There is no convincing scientific evidence that computer video display terminals are harmful to the eyes. While eyestrain from computers can be disruptive and unpleasant, it isn't thought to have any long-term or serious consequences.

"There are a number of factors that play a role in computer-related eyestrain," says Thomas Freddo, an optometrist at Boston Medical Center and a professor of ophthalmology, pathology, and anatomy at Boston University School of Medicine. "Some of these are related to the eyes, but some, like ergonomics and inappropriate lighting, are not."

Among the eye-related symptoms people may experience after looking at a computer screen for a long time are sore, tired, burning, itching, or dry eyes; blurred or double vision; difficulty in shifting focus between the monitor and source documents; difficulty in focusing on the screen image; increased sensitivity to light; and color fringes or afterimages when looking away from the monitor.

Freddo says the first thing an individual should do when experiencing eyestrain is to visit the eye doctor. An optometrist -- who treats most eye diseases -- can determine if an individual has a previously undiagnosed refractive error, meaning he needs eyeglasses. He can also determine if the individual has a binocular vision disorder, a problem in which the eyes have difficulty working together to hold a clear focus at a specific distance.

People who wear contact lenses may suffer less from eyestrain and more from symptoms related to irritation and dryness. When reading, an individual's blink rate drops, so contact lenses dry out between blinks, causing irritation and blurred vision. "Nothing keeps contacts happier than blinking," says Freddo.

Bifocal wearers may have particular problems with computer screens because most bifocals are prescribed for near reading (usually 16 to 20 inches). Most computer screens are placed far enough beyond that distance that the prescription is too strong, leading the individual to continually change his distance from the screen to keep clear focus. In addition, Freddo says, bifocal wearers may feel the need to move their eyes up and down to look through the bifocal, particularly patients who select the popular no-line, or progressive addition, bifocals. He recommends a separate eyeglass prescription -- not a bifocal -- designed for reading at computer-screen distance.

Many of the problems caused by computer screens are not eye-related, but are caused by the environment in which an individual works. Here are some tips that might help:

  • Place your monitor 18 to 30 inches away from your eyes, with the top of the screen at eye level or below so that you are looking slightly down at your work;
  • Place source documents on a stand at the same level, angle, and distance away from your eyes as your monitor. This way, your eyes won't have to adjust from the documents to the screen;
  • Keep your screen clear, as dust contributes to glare and reflection problems. Freddo recommends nonglare, antireflective coatings on glass or plastic rather than mesh screens, which cut down resolution;
  • Check the ambient light and glare in your office. Place the brightest lights off to the side, and close shades or blinds to prevent sunlight from coming in;
  • Take frequent breaks by looking away from the screen for 10 seconds every 10 minutes, and move around at least once every 2 hours, giving both your eyes and your body a rest.

"There really are no pharmacological or surgical issues related to eyestrain caused by computers," Freddo says, "unless dry contact lenses abrade the cornea. Most of the problems can be treated by making ergonomic and lighting changes in the office setting and getting good quality eye care, with binocular vision and other testing to determine if there are indeed problems with the eyes."


"Health Matters" is written in cooperation with staff members of Boston Medical Center. For more information on eyestrain or other health matters, call 638-6767.