Vision Health Management: Visual Ergonomics in the Workplace

  Reprinted from The RSI Network - Issue 38 - May'99

Dr. Jeffrey R. Anshel, BS, OD
Corporate Vision Consulting
Encinitas, California

Vision is our most precious sense. Our eyes are in constant use every waking minute of every day. The way we use our eyes can determine how well we work throughout our lifetime. Over 80% of our learning is mediated through our eyes, indicating the important role our vision plays in our daily activities. Vision disturbance is a silent enemy that only appears after a long period of continued stress.

In the past decade, computers have taken industry and business by storm. It is estimated that over 70 million Americans now use computers regularly. We are increasingly becoming an information society, and the price we are paying is our eyesight.

The human eye has been essentially unchanged for over 40,000 years in our evolution. However, in the last 100 years or so we have been gradually altering our viewing tasks from predominantly distance to near work. Today we spend a disproportionate amount of time involved in close work. To adapt to this change, our eyes have become increasingly near-sighted. Researchers have confirmed this shift toward increased near-sightedness in our society. This is much more prominent in the population of computer users. Let's look at the different factors that affect our eyes while using a computer.

The Terminal
Using a computer differs significantly from traditional reading in many ways. There is a difference in looking at a white piece of paper with black letters that reflects light versus looking at a (usually) black screen with various colored letters that is self-illuminated. The additional light coming from the screen dictates that less surrounding light is necessary. The light emanates from the screen by a process that continually refreshes a phosphor coating so the image doesn't fade. This refreshing of the coating must be accomplished at a rate of more than 60 times per second. If it occurs at a slower rate, the user will experience the "flicker" that is similar to that of an old fluorescent light. People experience this flicker differently, and screens have different flicker rates. This can be a very distracting and stressful experience for the terminal user. One can reduce flicker by dimming the brightness of the screen. However, that can lead to other potential problems, which will be discussed later.

Eye Position
There is a considerable difference in the normal eye position when looking at the terminal as compared to reading. Conventional reading is normally done while looking at a 14-16" working distance, with the reading material held in a lowered (about 40 degrees) position. The straight-ahead position used by many computer users is unnatural. The muscles must fight one another to achieve a balance and maintain the image correctly in the eyes. This can lead to fatigue, eyestrain, or headaches. Ideally, the center of the screen should be 7-10 inches below your horizontal line of sight.

Glare is any extraneous scattering of light. There are many sources of glare in most office situations: improperly positioned lamps, fluorescent lights, outdoor light, highly reflective surfaces, or any illuminated object. The glass surface a computer terminal can be highly reflective. While the eyes are in the straight-ahead position they are more susceptible to outside sources of light, especially those coming from the ceiling.

There are many ways to reduce glare. The first way should be with an anti-glare screen for the monitor. The most common screens are mesh or glass and each has its own advantages. Glass screens are generally better but may lead to further reflections if they don’t have anti-reflective coating. Although they are more bothersome to keep clean and are more expensive, they do an excellent job of reducing glare.

Secondly, reduce glare by positioning the screen properly. While the screen is off, angle it so that you can see no reflections of any lights on the front surface of the screen.

Another solution may be a bit more difficult to control. Traditional lens panels on fluorescent lights are often a significant source of glare. These units can be retrofitted with louvers that direct the light straight downward instead of allowing scattering. This will create a dimmer working environment but will be much more soothing on the eyes. Research has found that most offices are much too bright for terminal work. The surrounding illumination should be only three times as bright as the screen you are using.

If glasses are worn while using a computer, you'll probably benefit from a very slight pink or rose colored tint in the lens. This is a barely noticeable tint but will help to offset the scattering of light around the office.

Computer Glasses
If you wear glasses regularly, the prescription is usually designed to help you see better at a distance (while driving, for example). However, the power required for clear distant vision may be different from what will make your eyes most comfortable at 20-25 inches. How your eyes focus and work together will determine the proper prescription for glasses at the close distance.

If you haven't worn glasses at all before, get your eyes examined by your eye-care professional. Be sure to tell him or her that you work on a computer terminal and give them as much information about it as possible, i.e., working distance, lighting conditions, amount of time spent at the terminal, symptoms you experience, etc. Very often special computer glasses will be prescribed simply to ease the effect of long hours looking at the screen.

If you are over the age of 40, you probably have (or soon will) experienced difficulty changing focus to near objects. This is the usual decrease in the eyes' ability to focus as we age. Glasses used for reading and computer work can let you function normally again. If you already wear glasses for distance and experience difficulty focusing, then bifocals may be in your future. As the traditional bifocal is not well suited for computer vision, an alternate choice may be necessary. Some new lenses have no lines and provide for a full range of distance, intermediate, and near vision, so be sure to ask about as many alternatives as possible.

If you have contact lenses, you may be experiencing dryness and discomfort while working on your terminal. The first problem can often be attributed to the environment. In areas that have computer hardware, air filters are often used to dry the air to make the conditions optimal for the computer. Less moisture in the air causes your eye lenses to dry. In addition, the cooling fans of the units themselves draw more dust into the area, creating more problems. There is also a tendency to blink less when doing intense close work. Lubricating drops recommended by your doctor will help relieve the symptoms of dryness.

Vision Therapy
Sometimes it is not enough to take precautions and/or use glasses. If your visual system is not able to make necessary adjustments to work effectively, you probably could benefit from vision therapy.

Vision therapy is a program optometrists offer to teach people how to use their eyes properly and with less effort. It is an integrated program of techniques and procedures that help the person improve all aspects of vision, including general coordination, balance, hand-eye coordination, eye movements, eye teaming, and focusing efficiency. It is done on patients of all ages for any number of different problems. Your local Optometric Society can give you names of doctors in your area who specialize in vision therapy.

Computer Vision Testing
A recently introduced software program has been shown to be effective in conducting a vision screening test on the computer and determining VDT-related visual stress. The Eye-Computer Ergonomic Evaluation (Eye-CEE) System for VDT Users® consists of an on-line questionnaire as well as vision tests that can determine if your symptoms are related to your vision or to your environment. The program produces reports that can be taken to your doctor to help do a more effective examination of your vision.

Eye Self-Care
There are many things you can do for yourself to reduce computer-related eyestrain. I've narrowed these down to a "3 B's" approach: Blink, Breathe, and Break.

Blink: Blinking is an automatic function. It also happens to be the fastest reflex in the body! We usually blink at a rate of about 12-15 times a minute in normal situations. (Unfortunately, we have not yet figured out what a normal situation is.) We blink more often when we are excited, stimulated, anxious, talking, and doing general physical activity. We blink much less frequently while quiet, which includes reading, thinking, and concentrating on a particular task. This staring can strain the eyes. Blinking allows our eyes to rest for a short time, and also cleans and re-wets the eye surface to maintain clear vision. Because blinking is so automatic, it might take some concentration at first to make sure you maintain a normal blink rate while working at a terminal. Just being aware of this concern will allow you to blink more normally.

Breathe: Our breath is our life. Our entire body is governed by the exchange of oxygen and carbon dioxide from the breathing process. When we reach a stressful situation in our activities, we tend to hold our breath to "break through" the situation because the breath can control our muscle activity. If we hold our breath, we may tighten muscles in places where we are not even aware. Correct breathing—even and steady—can relax the eye muscles as well.

Breaks: With the intense concentration we apply to computer work it is not surprising that we need more breaks. Our eyes were not designed to be used at such a close distance for a long period of time. I've devised a plan of breaks that will allow you to do the maximum amount of work and still allow you to relax your eyes. These are called: Micro-, Mini- and Maxi-Breaks.

Micro-Break: This break is only for about 10 seconds and should be taken about every 10 minutes. Look far away from your terminal (at least 20 feet) and breathe and blink easily. Keep your eyes moving while looking at different distant objects. This should not interfere with your work or your concentration.

Mini-Break: Take this break about every hour; it should last about five minutes. Stand up and stretch. I often recommend doing eye exercises during this break so the eyes can flex and be used in different seeing situations. Ask your eye doctor which exercises he or she would recommend.

Maxi-Break: This could be a "coffee" break or lunch. The maxi-break is a "get up and move" type of break that will allow your blood to start flowing again and get you more energized. This kind of break should be taken every few hours.

There is no one solution to all types of problems encountered with computer use. However, education and common sense can help to reduce your potential risk. Our productivity is supposed to be increased with computer use, but this should not occur at the expense of our eyesight. We need to co-exist with computers and use them to their fullest potential. The answer to many of these problems may be right before your eyes!

About the Author
Dr. Jeffrey Anshel graduated from the Illinois College of Optometry and served as a lieutenant in the U.S. Navy in San Diego, where he established the Navy's first vision therapy center. In 1990, he published Healthy Eyes, Better Vision, a layman’s reference book containing practical advice regarding vision care. Taylor & Francis has just published his second book, Visual Ergonomics in the Workplace. Dr. Anshel is currently the principal of Corporate Vision Consulting, where he addresses issues related to visual demands on computer users. He also maintains a private practice in Carlsbad, California.

Return to Articles Index



Last Updated: 11/03/00