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Protecting eyes from computer screen
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Eye discomfort in the office
Computer and Health
What is the significance of "good" lighting?
Office work is visually demanding and has always required good lighting for maximum comfort and productivity. "Good" lighting means providing enough illumination so that people can see printed, handwritten or displayed documents clearly but are not blinded by excessively high light levels (a cause of glare).
The introduction of computers in the 1970's increased the visual demands of office work and made lighting design even more challenging. While typewriters were being exchanged for computers, the need for redesigning or rearranging office lighting was commonly overlooked.
What are signs of poor lighting?
The most common complaints resulting from poor lighting are:
- eyestrain,
- eye irritation,
- blurred vision,
- dry burning eyes, and
- headaches.
Poor lighting affects not only the ocular system but can also contribute to stiff necks and aches in shoulder area. These problems can occur when people adopt poor or awkward postures when trying to read something under poor lighting conditions.
Why do computers create a challenge for lighting designers?
The monitor itself is a source of light. As such, it does not require additional illumination from other sources. In fact, the screen itself can cause glare if the brightness and contrast controls are not properly adjusted.
An additional challenge occurs because most office work involves using the monitor and paper documents at the same time. Paper documents require a higher light level than the monitor. A desk lamp (any type of soft task light) can be used to illuminate documents while avoiding excessive light near the monitor. Glare can also result from an improper match or excessive contrast in light levels between the monitor screen and the paper.
The monitor also acts as a mirror. Reflections of objects, shiny walls, and any light source (specifically windows and overhead lighting) all cause glare. Eye discomfort can result but glare also forces the user into an awkward position as they try to avoid having the glare in their eyes. These positions lead to aches and pains in the upper body that, in turn, can also aggravate eye strain!
The quality of the images on the monitor is another important factor. Reading and interpreting blurred, fuzzy, tiny, or otherwise illegible characters for hours a day can strain the operators' eyes.
What else in the computerized office contributes to the eye discomfort?
Other examples of work-related risk factors that contribute to eye discomfort are:
- maintaining a fixed and close visual distance for a long time,
- glare from the unshaded or un-diffused lighting fixtures,
- poor lighting, involving unchanged (and unchangeable) levels of illumination,
- unsuitable workstations (dimensions and arrangement),
- low ambient humidity,
- uncorrected vision problems, and
- lack of colour variety in one's surroundings.
Are there any non-visual effects of poor lighting?
When people are exposed to glare or have uncorrected vision problems, they tend to lean forward or backward in an attempt to compensate. An awkward body position leads to eye strain and accelerates postural fatigue that, in turn, contributes to musculoskeletal injuries (MSI).
How can eye discomfort be reduced?
Overhead lighting
- Use filters to diffuse overhead lighting.
- Dim overhead lights.
- Keep in mind that recommended level of light in offices 300 - 500 lux is not a must. It applies in the situation where there is no task lamp in use.
Windows and walls
- Cover windows with adjustable blinds.
- Use matte finishes on walls, floors and furniture.
Monitor
- Adjust the brightness and contrast according to your preference.
- Use a light colour for the background.
- Place the monitor parallel (not directly below) with overhead lights.
- Angle the monitor away from lights and windows.
- Make sure that the task lamp illuminates the document and not the monitor.
Should anti-glare screens be used?
In general, anything between the operator and screen compromises the quality of the image. It is far better to control glare by proper lighting design and placement of the monitor than by use of an anti-glare screen. Many monitors currently available are already equipped with low reflective screens.
What can you do to reduce eye strain?
The ability to focus on objects at various distances decreases with age (presbyopia). Commonly, by their forties people cannot clearly see objects at close range with the naked eye. This is a gradual change, and has to be regarded as an important component in designing visual environments, particularly when the job involves computer work. Uncorrected vision may be an additional source of eye discomfort. It may have further consequences resulting in aches and pains because of awkward postures or positions adopted to "see better".
- Check your vision every one or two years, as recommended by your eye specialist.
- Provide your eye examiner with information about your job.
- Consider using task-specific computer glasses.
Depending on the amount of time you work at a keyboard, the kind of vision correction needed, and your personal preferences, your eye specialist may recommend bifocals, trifocals or even a separate pair of glasses for computer work.
Focusing your eyes on objects at the same distance and angle for prolonged periods of time can contribute to eye strain.
- Every few minutes look away from the screen for a few seconds.
- Look around.
- Focus your vision on distant objects.
- Blink several times.
Frequently "stretching" your eyes like this will prevent feelings of fatigue from accumulating.
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Health & safety
Because there are so many children of varying ages and sizes in a before
and after school care program, it is essential to pay attention to health
and safety issues. Children need to be taught simple safety principles from
the time they begin using computers. Don't overlook the obvious when children
use computers. For children as well as adults, bad posture can cause sore wrists, eye fatigue, headaches, neck strain and even back pain. Since kids may be using computers both at home and at school, there is the potential for problems to develop over time.
To prevent eye problems, avoid flickering lights or glare on the screen, and look away from the monitor frequently. (This is true for video games also.) Get up and walk around (moving around rests both the eyes and the body), focus on a distant object, remember not to stare at the screen, and blink often.
Furniture that is used should be safe and adjustable so it fits each child. If you can't find sturdy, adjustable furniture, have some available that fits the different sizes of the children using it. Because many sizes and shapes of children will probably be using a computer area that has been set up for one "size" of students, careful monitoring of the physical set up should occur when each new student sits down. Make the appropriate adjustments for each child according to the guidelines listed below.
FAQs on myopia
Q. What is myopia?
A. Myopia is commonly known as "short-sightedness". A person with myopia is able to see close objects clearly but objects that are further away will appear blurred.
When the normal eye looks at an object, light rays from the object enter our eye. These light rays are bent at the cornea and the eye lens before forming an image on the inner layer of the eye called the retina. This image is then transmitted by nerve signals to the brain. The brain interprets these signals so that we see the object.
If the light rays are focused directly on the retina, we see a sharp image. Myopia occurs when the light rays from distant objects are focused in front of the retina instead of on it, resulting in blurred images on the retina. This is usually because the eyeball is too long or sometimes the cornea and lens do not bend the light rays properly.
Q. What are the complications of myopia?
A. Undetected myopia before the age of 6 years old can lead to amblyopia (lazy eye) and eventually blindness in the affected eye.
Severe myopia can lead to potentially blinding conditions such as _ retinal detachment (a condition when the retina separates from the eyeball)
Your health - headaches and eye strain
What are headaches and eyestrain?
Headaches can be caused by many different factors and are one of the most common reasons people visit their GP. Most headaches are not serious and usually disappear on their own. They can be relieved by mild painkillers, or a positive change in lifestyle.
Eyestrain is also a common complaint among people doing 'close' work e.g. those who work using computer monitors. Eyestrain can be a trigger for headaches, but can usually be avoided by following simple guidelines.
What are the signs of headache or eyestrain?
A headache can range from a mild, throbbing feeling to a sharp, stabbing pain. Headaches can affect your whole head or just a part of it. The pain may move around, affect your vision or even cause nausea and vomiting. The two most common types of headache are tension headaches and migraine.
Tension headaches do not usually last for a long time. Common symptoms of a tension headache include
Vision / eye strain
Visual problems, such as eyestrain and irritation, are among
the most frequently reported complaints by computer operators. These
visual symptoms can result from improper lighting, glare from the
screen, poor positioning of the screen itself, or copy material that is
difficult to read. These problems usually can be corrected by adjusting
the physical and environmental setting where the computer users work.
For example, work stations and lighting can and should be arranged to
avoid direct and reflected glare anywhere in the field of sight, from
the display screen, or surrounding surfaces.
You also can reduce eyestrain by taking vision breaks, which
may include exercises to relax eye muscles after each hour or so of
operating a computer. Changing focus is another way to give eye muscles
a chance to relax. You only need to glance across the room, or out the
window, from time to time and look at an object at least 20 feet away.
Other eye exercises may include rolling or blinking the eyes, or
closing them tightly for a few seconds.
