EYE : Computer Eye Strain

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samedi 22 septembre 2018

Children and Computer Vision Syndrome

How frequently do young children use computers and other digital devices these days? The answer may astound you. And it could result in a problem called computer vision syndrome.

Statistics

According to the National Center for Education Statistics, 94 percent of American children ages 3 to 18 currently have access to a computer at home.

Also, research reported by Common Sense Media shows:

Should you worry about how much time your child spends in front of the computer every day?

98 percent of U.S. households with kids under the age of 8 have some type of mobile device (smartphones, tablet computers, etc.) — the same percentage as the amount of homes that have a television.
Kids under age 8 now spend an average of more than two hours a day viewing digital displays. Among older children, screen time jumps to six hours per day for ages 8 to 10 and nine hours per day for kids 11 to 14 years old.

Because this rapid increase in the use of computers and other digital devices by children has occurred within just the past decade or two, there’s no conclusive data regarding the potential harmful effects of too much screen time on kids' eyes — both in the short-term and later in life.

But some eye doctors are concerned.

Screen time risks

A primary concern that many eye care professionals have is that significant hours of computer use by kids may put them at greater risk for developing myopia (nearsightedness).

Research appears to confirm that opinion. A large study conducted by the National Eye Institute found that the prevalence of nearsightedness among Americans has increased from 25 percent to 41.6 percent of the population over the past 30 years — an increase of more than 66 percent.

The time frame of this significant increase in myopia parallels the ramp-up of hours of computer use worldwide. And the greatest risk for nearsightedness and myopia progression takes place in childhood.

But another concern is that more eye doctors are seeing children in their offices who are experiencing symptoms of computer vision syndrome (CVS) — a condition characterized by a combination of eye strain, headaches and fatigue-related discomfort and posture problems.

High-energy blue light emitted by the screens of computers and other digital devices appears to contribute to CVS symptoms. Also, research suggests blue light has the potential to cause oxidative stress on the retina of the eye over time. Some researchers believe this stress on the retina might increase one's risk for age-related macular degeneration later in life.

More research is needed to determine the long-term effects of blue light from computer use on the eye. But many eye doctors are urging caution, because when today's children become tomorrow's seniors, they will have been exposed to far more blue light from digital devices than previous generations have been.

What to do

Symptoms of computer vision syndrome — headaches, eye strain, posture problems, etc. — are good reasons to schedule an eye exam for your child. Addressing these issues early not only will relieve unnecessary discomfort, it may also reduce the risk of vision problems or eye health concerns later on.

[If you need an eye care provider, click here to find an eye doctor near you.]

In addition to scheduling an eye exam, here are a few helpful things you can encourage your child to do to decrease the risk of computer vision syndrome and keep his eyes comfortable, seeing well, and healthy:

Take frequent "eye breaks." A very helpful technique when using a computer or other digital devices is called the "20-20-20 rule" — every 20 minutes, stop looking at your screen for at least 20 seconds to look at something at least 20 feet away. This relaxes your eye muscles to prevent fatigue that leads to eye strain and headaches.
Stretch. The short breaks associated with the 20-20-20 rule are a great time for your child to get up from her desk (or put down her device) to stand up and stretch. Performing a yoga pose or two also is a good idea. (OK, she shouldn't do these things in the middle of a class at school, but you get the idea!) The purpose here is to relieve muscle tension that causes eye, head, neck and overall body discomfort. Stretching also helps increase blood flow to increase alertness.
Go outdoors. Again, not during class time, but spending more time outdoors will get your child moving and relieve tension associated with computer vision syndrome. There also is research that shows spending more time outdoors may decrease the risk of becoming nearsighted!

And if your child already wears glasses, ask your eye care professional about photochromic lensesand anti-reflective coating. These eyewear products can increase visual comfort and decrease your child's exposure to blue light both indoors and outside.

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Computer Vision Syndrome And Computer Glasses FAQ

Ernest About Eye , Computer Eye Strain

According to The Vision Council, a recent survey of more than 10,000 adults found that 65 percent of Americans experience digital eye strain symptoms — such as dry, irritated eyes, blurred vision, eye fatigue and headaches — when using a computer, smartphone and other digital devices.

And eye strain and other symptoms of computer vision syndrome (CVS) don't occur only in adults. Millions of children work at a computer every day, either at home or in school. Prolonged computer use can stress a child's eyes and may affect normal vision development.

What are the symptoms of computer vision syndrome?

If you or your child spend more than two hours per day in front of a computer screen, it's likely you will experience some degree of computer vision syndrome. Symptoms of CVS include:

Headaches
Loss of focus
Burning eyes
Tired eyes
Red eyes

What causes computer vision syndrome?

Computer eye strain and computer vision syndrome are caused by our eyes and brain reacting differently to characters on a computer screen than they do to printed characters. Our eyes have little problem focusing on printed material that has dense black characters with well-defined edges. But characters on a computer screen don't have the same degree of contrast and definition.

Words and images on a computer screen are created by combinations of tiny points of light (pixels), which are brightest at the center and diminish in intensity toward their edges. This makes it more difficult for our eyes to maintain focus on them. Instead, our eyes want to drift to a reduced level of focusing called the "resting point of accommodation" or RPA.

Our eyes involuntarily move to the RPA and then strain to regain focus on the screen. This continuous flexing of the eyes' focusing muscles creates the fatigue and eye strain that commonly occur during and after computer use.

Using proper computer eyewear can prevent eye strain.

What can I do about it?

To reduce your risk of computer eye strain and computer vision syndrome, see an optometrist or ophthalmologist who specializes in computer vision care.

During a computer vision exam, your eye doctorwill perform tests to detect any vision problems that might contribute to CVS. Depending on the outcome of the exam, your doctor may prescribecomputer eyeglasses to help you work more comfortably at your computer.

In addition to increasing comfort during computer use, recent studies have shown that computer eyeglasses can increase computer worker productivity, with cost savings to employers who provide the eyewear.

Will glare screens prevent CVS?

Anti-glare filters for computer screens may increase comfort somewhat, but they will not solve all your computer vision problems. These filters only reduce glare from reflections on the computer screen and do not reduce the visual problems related to the constant refocusing of your eyes when you work at a computer.

In order to reduce computer-related eye strain effectively, you may need computer eyewear to help your eyes focus on your screen more comfortably. Also, anti-reflective coating is highly recommended for computer eyeglasses. Anti-reflective (AR) coating reduces reflections on the front and back surfaces of eyeglass lenses that cause glare and interfere with your ability to focus on images on your screen.

Will computer eyeglasses make the screen clearer?

Yes, because computer glasses eliminate the constant refocusing effort that your eyes go through when viewing the screen.

Do computer eyeglasses look like safety glasses?

Also, clinical studies have shown that having the correct prescription in computer eyeglasses increases productivity and accuracy.

No. Almost any style of frame can be used for computer glasses.

What kinds of lenses are prescribed for computer glasses?

The best type of lenses for computer glasses usually depends on your age. If you are in your 40s or older, it's likely you have some degree of presbyopia. If so, multifocal lenses will usually be your best choice because they provide better depth of focus than single vision lenses. This will let you see your computer screen clearly and also see objects that are closer and farther away than your screen.

Single vision lenses also are a good solution for computer glasses, though your depth of focus will be more limited with these lenses if you are presbyopic. Your eye doctor will help you decide whether multifocal or single vision lenses are the best solution for your work environment and your visual needs.

What about tints for computer lenses?

If you work in a brightly lit office, it might be a good idea to have a mild tint added to the lenses of your computer glasses.

But be aware that tints alone don't address the underlying cause of computer eye strain, which is focusing fatigue.Lightly tinted lenses will reduce the amount of light entering your eyes to more comfortable levels and may help reduce eye strain.

Does every computer user need computer glasses?

With studies suggesting that most computer users experience some level of eye discomfort from computer work, it's reasonable to say that most people who work on a computer more than a couple hours daily could benefit from computer eyewear.

If you experience tired eyes, overall fatigue or discomfort when working at your computer, schedule a computer vision exam. Your eye doctor can help you decide if computer eyeglasses are right for you.

If I don't have symptoms of CVS, do I still need computer eyewear?

Maybe. According to a study at the University of Alabama at Birmingham School of Optometry, even computer users who are not experiencing computer vision syndrome symptoms might benefit from computer glasses.

The study found that computer workers with no visual complaints often experience reduced productivity and accuracy at the computer. So even if you don't notice eye strain or other symptoms of CVS, it's a good idea to get an eye exam from a computer vision specialist if you spend a good amount of time each day in front of a computer.

In some cases, some or all of the cost of computer glasses is covered by vision insurance.Will insurance pay for computer glasses?

If you have medical coverage, but not vision insurance, the cost of your computer vision exam may be covered by your medical carrier.

Some vision insurance policies entitle you to an annual eye exam, which could be used to cover the computer vision exam and a portion of the cost of your computer eyewear. Also, be sure to check your employee benefits at work. Some companies provide eye exams and eyewear for their employees who work at computers.

Will my reading glasses work at the computer?

Reading glasses usually are not the best solution for computer use.

Eyeglasses prescribed for reading typically will optimize your vision at a distance of 14 to 16 inches from your eyes, which is considered the standard reading distance. But for the greatest comfort, your computer screen should be positioned farther away — at a distance of 20 to 24 inches from your eyes. For the best vision at this distance, a different eyeglass prescription is usually required.

Does computer vision syndrome affect worker productivity?

Yes, research has shown that this is true. Even in cases when a computer worker's vision correction is only slightly off, productivity and accuracy at the computer can still suffer.

And as the day progresses, these losses increase. Using your eyes to view a computer for many hours a day is analogous to your eye muscles being forced to do push-ups for hours and hours. Over time, muscle fatigue will significantly affect productivity, accuracy and comfort. Computer glasses can reduce eye fatigue and improve productivity.

Isn't ergonomics the solution to computer eye strain?

Ergonomics is important — changing your computer workstation to facilitate good posture can certainly help minimize some physical symptoms of CVS. But ergonomics alone cannot solve a visual problem. Wearing prescription computer eyeglasses typically is more helpful than ergonomics for reducing the risk of computer eye strain.

Will wearing computer eyeglasses make my eyes worse?

No. In fact, wearing specially prescribed computer glasses when working at your computer might help keep your eyes from getting worse by reducing excessive focusing demands on your eyes. This is particularly true for teenagers, whose eyes may be more susceptible to progressive nearsightedness from focusing fatigue.

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Computer Glasses: Relieving Computer Eye Strain

Ernest About Eye , Computer Eye Strain

When you work at a computer for any length of time, it's common to experience eye strain, blurred vision, red eyes and other symptoms of computer vision syndrome (CVS). This is because the visual demands of computer work are unlike those associated with most other activities.

If you're under age 40, eye strain or blurred vision during computer work may be due to an inability of your eyes to remain accurately focused on your screen or because your eyes have trouble changing focus from your keyboard to your screen and back again for prolonged periods. These focusing (accommodation) problems often are associated with CVS.

If you're over age 40, the problem may be due to the onset of presbyopia — the normal age-related loss of near focusing ability. This, too, can cause CVS symptoms.

What can you do? For starters, have a comprehensive eye exam to rule out vision problems and update your eyeglasses prescription. Studies show that even small inaccuracies in your prescription lenses can contribute to computer vision problems.*

If your glasses are up-to-date (or you don't need prescription eyewear for most tasks) and you continue to experience eye discomfort during computer work, consider purchasing customized computer glasses. These special-purpose glasses are prescribed specifically to reduce eye strain and give you the most comfortable vision possible at your computer.

Why Computer Glasses?

Computer glasses differ from regular eyeglasses or reading glasses in a number of ways to optimize your eyesight when viewing your computer screen.

Eyezen+ is one of the newest lenses designed to optimize vision and comfort during digital device use. According to manufacturer Essilor, the lens filters at least 20 percent of blue light, but unlike other blue light filters, looks clear instead of tinted. It's available in both prescription and non-prescription.

Computer screens usually are positioned 20 to 26 inches from the user's eyes. This is considered the intermediate zone of vision — closer than driving ("distance") vision, but farther away than reading ("near") vision.

Children and young adults who need prescription eyeglasses usually are prescribed single vision lenses. These lenses correct the wearer's nearsightedness, farsightednessand/or astigmatism, and the shape of the lens inside the eye automatically adjusts to provide the extra magnifying power required for computer vision and near vision.

When a person's close-up vision becomes less clear due to presbyopia after age 40, this age-related loss of natural focusing power affects reading and seeing a smartphone or computer vision clearly and comfortably. Bifocals can provide clear distance and near vision, but intermediate vision (needed for computer use and seeing your smartphone) often remains a problem. And progressive lenses or trifocals, though they offer some help for intermediate vision, often don't have a large enough intermediate zone for comfortable computer work.

Without computer eyeglasses, many computer users often end up with blurred vision, eye strain, and headaches — the hallmark symptoms of computer vision syndrome. Worse still, many people try to compensate for their blurred vision by leaning forward, or by tipping their head to look through the bottom portion of their glasses. Both of these actions can result in a sore neck, sore shoulders and a sore back.

Though they sometimes are called "computer reading glasses," it's best to call eyewear designed specifically for computer use "computer glasses" or "computer eyeglasses" to distinguish them from conventional reading glasses.

Generally, computer glasses have about 60 percent the magnifying power of reading glasses. But the optimal magnification depends on how far you prefer to sit from your computer screen and how close you like to hold your digital devices.

Computer glasses also should accurately correct any astigmatism you might have, and precise measurements should be taken to insure the optical center of each lens is directly in front of your pupils when you are using your preferred working distance.

For these reasons, computer glasses should be customized to your individual needs. Using weaker, non-prescription reading glasses for computer work and seeing your digital devices typically won't provide the accurate vision correction you need for sustained clarity and comfort.

Computer glasses put the optimum lens power for viewing your computer screen right where you need it for a clear, wide field of view without the need for excessive focusing effort or unhealthful postures. University research also shows custom computer eyewear can significantly increase worker productivity.

Lens Designs For Computer Eyewear

Many special purpose lens designs work well for computer glasses. Because these lenses are prescribed specifically for computer use, they are not suitable for driving or general purpose wear.

Computer vision syndrome causes eye fatigue, which can make you feel tired in general.

The simplest computer glasses have single vision lenses with a modified lens power prescribed to give the most comfortable vision at the user's computer screen. This lens power relaxes the amount of accommodation required to keep objects in focus at the distance of the computer screen and provides the largest field of view.

Single vision computer glasses reduce the risk of eye strain, blurred vision and unnatural posture that can cause neck and back pain, and can be used comfortably by young and old computer users alike.

Another popular lens design for computer glasses is the occupational progressive lens — a no-line multifocal that corrects near, intermediate, and, up to a point, distance vision.

Occupational progressive lenses have a larger intermediate zone than regular progressive lenses for more comfortable vision at the computer. But this leaves less lens area for distance vision, so these lenses are not recommended for driving or other significant distance vision tasks.

Other lenses used for computer glasses include occupational bifocal and trifocal lenses. These lined multifocal lenses have larger zones for intermediate and near vision than regular bifocals and trifocals, and the position of the intermediate and near zones can be customized for your particular computer vision needs.

Your optometrist or ophthalmologist can help you decide which lens design will best suit your needs for computer glasses.

Lens Coatings And Tints

For maximum viewing comfort, the lenses of your computer glasses should include anti-reflective coating. Sometimes called anti-glare treatment, anti-reflective (AR) coating eliminates reflections of light from the front and back surfaces of your lenses that can cause eye strain.

Also, computer glasses with photochromic lenses can shield your eyes from potentially harmful high-energy visible blue light from your computer screen and digital devices — and automatically darken in sunlight outdoors, too.

Your eye doctor may also recommend adding a light tint to computer glasses to reduce glare caused by harsh overhead lighting and to enhance contrast.

For more details about anti-reflective coating and tints for your computer glasses, consult your eye care professional.

Where To Buy Computer Glasses

Resist the temptation to buy over-the-counter reading glasses for use as computer glasses.

Because an accurate eyeglasses prescription is essential if you want to get the full benefits from computer glasses, it's best to purchase this eyewear from a knowledgeable eye care professional.

Prior to scheduling your eye exam, measure how far you like to sit from your computer. Measure from the bridge of your nose to the surface of your computer screen.

Bring this measurement with you to your exam so your eye doctor can use it to help determine the optimum lens power for your computer glasses.

Also, read these computer ergonomics tips to help you arrange your computer workstation for optimum comfort.

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Computer Eye Strain: 10 Steps For Relief

Ernest About Eye , Computer Eye Strain

With so many of us using computers at work, computer eye strain has become a major job-related complaint. Studies show that eye strain and other bothersome visual symptoms occur in 50 to 90 percent of computer workers.

These problems can range from physical fatigue, decreased productivity and increased numbers of work errors, to minor annoyances like eye twitching and red eyes.

Here are 10 easy steps you can take to reduce your risk of computer eye strain and other common symptoms of computer vision syndrome (CVS):

1. Get a comprehensive eye exam.

Having a routine comprehensive eye exam is the most important thing you can do to prevent or treat computer vision problems. If you haven't had an eye exam in over a year, schedule a visit with an eye doctor near you.

According to the National Institute of Occupational Safety and Health (NIOSH), computer users should have an eye exam before they start working on a computer and once a year thereafter.

During your exam, be sure to tell your eye doctor how often you use a computer at work and at home. Measure how far your eyes are from your screen when you sit at your computer, and bring this measurement to your exam so your eye doctor can test your eyes at that specific working distance.

2. Use proper lighting.

Eye strain often is caused by excessively bright light either from outdoor sunlight coming in through a window or from harsh interior lighting. When you use a computer, your ambient lighting should be about half as bright as that typically found in most offices.

Eliminate exterior light by closing drapes, shades or blinds. Reduce interior lighting by using fewer light bulbs or fluorescent tubes, or use lower intensity bulbs and tubes. If possible, position your computer monitor or screen so windows are to the side, instead of in front or behind it.

Many computer users find their eyes feel better if they can avoid working under overhead fluorescent lights. If possible, turn off the overhead fluorescent lights in your office and use floor lamps that provide indirect incandescent or halogen lighting instead.

Sometimes switching to "full spectrum" fluorescent lighting that more closely approximates the light spectrum emitted by sunlight can be more comforting for computer work than regular fluorescent tubes. But even full spectrum lighting can cause discomfort if it's too bright. Try reducing the number of fluorescent tubes installed above your computer workspace if you are bothered by overhead lighting.

3. Minimize glare.

Glare on walls and finished surfaces, as well as reflections on your computer screen also can cause computer eye strain. Consider installing an anti-glare screen on your monitor and, if possible, paint bright white walls a darker color with a matte finish.

Again, cover the windows. When outside light cannot be reduced, consider using a computer hood.

If you wear glasses, purchase lenses with anti-reflective (AR) coating. AR coating reduces glare by minimizing the amount of light reflecting off the front and back surfaces of your eyeglass lenses.

DIGITAL EYE STRAIN NEWS

Do You Spend Time On Your Phone Playing Pokemon GO?

The Pokemon GO app has been praised for getting users outside, walking and exploring communities. However, possible eye health risks could be associated with lots of time spent staring at a mobile device — beyond accidentally walking into things!

Image: Matthew Corley / Shutterstock.com

While more research is needed to determine if prolonged digital device use causes permanent damage to the eyes, many eye doctors are concerned about the effects of blue (HEV) light emitted from digital devices. Animal studies have shown that exposure to high levels of HEV light can damage tissue in the retina, possibly leading to conditions like macular degeneration.

In addition to potential damage from blue light, Pokemon GO players could experience digital eye strain while playing for long periods of time. Reports say that individuals are using the app for an average of more than 43 minutes a day.

Players should follow the "20-20-20" rule: take a break every 20 minutes and look at something 20 feet away for at least 20 seconds. This exercise helps relieve digital eye strain, which can cause dry or irritated eyes, blurred vision and more. —N.B.

4. Upgrade your display.

If you have not already done so, replace your old tube-style monitor (called a cathode ray tube or CRT) with a flat-panel liquid crystal display (LCD), like those on laptop computers.

LCD screens are easier on the eyes and usually have an anti-reflective surface. Old-fashioned CRT screens can cause a noticeable "flicker" of images, which is a major cause of computer eye strain. Even if this flicker is imperceptible, it still can contribute to eye strain and fatigue during computer work.

Complications due to flicker are even more likely if the refresh rate of the monitor is less than 75 hertz (Hz). If you must use a CRT at work, adjust the display settings to the highest possible refresh rate.

When choosing a new flat panel display, select a screen with the highest resolution possible. Resolution is related to the "dot pitch" of the display. Generally, displays with a lower dot pitch have sharper images. Choose a display with a dot pitch of .28 mm or smaller.

Flicker is not an issue with LCD screens, since the brightness of pixels on the display are controlled by a "backlight" that typically operates at 200 Hz.

If you see a lower refresh rate (e.g. 60 Hz) noted on an LCD screen, don't worry — this refers to how often a new image is received from the video card, not how often the pixel brightness of the display is updated, and this function typically is not associated with eye strain.

Finally, choose a relatively large display. For a desktop computer, select a display that has a diagonal screen size of at least 19 inches.

5. Adjust your computer display settings.

Adjusting the display settings of your computer can help reduce eye strain and fatigue. Generally, these adjustments are beneficial:

Brightness. Adjust the brightness of the display so it's approximately the same as the brightness of your surrounding workstation. As a test, look at the white background of this Web page. If it looks like a light source, it's too bright. If it seems dull and gray, it may be too dark.
Text size and contrast. Adjust the text size and contrast for comfort, especially when reading or composing long documents. Usually, black print on a white background is the best combination for comfort.
Color temperature. This is a technical term used to describe the spectrum of visible light emitted by a color display. Blue light is short-wavelength visible light that is associated with more eye strain than longer wavelength hues, such as orange and red. Reducing the color temperature of your display lowers the amount of blue light emitted by a color display for better long-term viewing comfort.

For computers running on a Microsoft Windows operating system, display settings can be adjusted in Control Panel. For an Apple computer, display settings are found in Systems Preferences (in the Applications folder in Finder).

In some cases, the color temperature of a desktop computer monitor is adjusted on the display itself.

EYE COMFORT TIPS Text displaying on 4 different types of backgrounds

Text Size and Color on Your Digital Screen

To avoid eye strain, at what size should your computer display text? According to computer vision syndrome expert Dr. James Sheedy, it should be three times the smallest size that you can read from your normal viewing position.

The best color combination for your eyes is black text on a white background, though other dark-on-light combinations also work well.

If you use Windows 7, you can adjust text size and color by going to the Start menu, opening the Control Panel and choosing Display. Here you can also adjust your screen's resolution and brightness, for best visual comfort.

6. Blink more often.

Blinking is very important when working at a computer; blinking moistens your eyes to prevent dryness and irritation.

When working at a computer, people blink less frequently — about one-third as often as they normally do — and many blinks performed during computer work are only partial lid closures, according to studies.

Tears coating the eye evaporate more rapidly during long non-blinking phases and this can cause dry eyes. Also, the air in many office environments is dry, which can increase how quickly your tears evaporate, placing you at greater risk for dry eye problems.

If you experience dry eye symptoms, ask your eye doctor about artificial tears for use during the day.

By the way, don't confuse lubricating eye drops with the drops formulated to "get the red out." The latter can indeed make your eyes look better — they contain ingredients that reduce the size of blood vessels on the surface of your eyes to "whiten" them. But they are not necessarily formulated to reduce dryness and irritation.

To reduce your risk of dry eyes during computer use, try this exercise: Every 20 minutes, blink 10 times by closing your eyes as if falling asleep (very slowly). This will help rewet your eyes.

To ease eye strain, make sure you use good lighting and sit at a proper distance from the computer screen.

7. Exercise your eyes.

Another cause of computer eye strain is focusing fatigue. To reduce your risk of tiring your eyes by constantly focusing on your screen, look away from your computer at least every 20 minutes and gaze at a distant object (at least 20 feet away) for at least 20 seconds. Some eye doctors call this the "20-20-20 rule." Looking far away relaxes the focusing muscle inside the eye to reduce fatigue.

Another exercise is to look far away at an object for 10-15 seconds, then gaze at something up close for 10-15 seconds. Then look back at the distant object. Do this 10 times.

This exercise reduces the risk of your eyes' focusing ability to "lock up" (a condition called accommodative spasm) after prolonged computer work.

Both of these exercises will reduce your risk of computer eye strain. Also, remember to blink frequently during the exercises to reduce your risk of computer-related dry eye.

COMPUTER VISION NEWS

Are You Keeping Your Doctor In The Dark About Your Digital Device Use?

January 2017 — According to a nationwide survey of 9,840 American adults, 87 percent use digital devices more than two hours per day and more than 52 percent regularly use two digital devices simultaneously.

Read this new report on a survey about blue light and digital device use.

The study showed that kids are impacted, too. Indeed, 76.5 percent of parents indicated that their children had more than two hours ofscreen time per day, and 55.6 percent said their kids experienced symptoms of digital eye strain after two hours of screen time.

8. Take frequent breaks.

To reduce your risk for computer vision syndrome and neck, back and shoulder pain, take frequent breaks during your computer work day.

Many workers take only two 15-minute breaks from their computer throughout their work day. According to a recent NIOSH study, discomfort and eye strain were significantly reduced when computer workers took four additional five-minute "mini-breaks" throughout their work day.

And these supplementary breaks did not reduce the workers' productivity. Data entry speed was significantly faster as a result of the extra breaks, so work output was maintained even though the workers had 20 extra minutes of break time each day.

During your computer breaks, stand up, move about and stretch your arms, legs, back, neck and shoulders to reduce tension and muscle fatigue.

Check your local bookstore or consult your fitness club for suggestions on developing a quick sequence of exercises you can perform during your breaks and after work to reduce tension in your arms, neck, shoulders and back.

9. Modify your workstation.

If you need to look back and forth between a printed page and your computer screen, this can cause eye strain. Place written pages on a copy stand adjacent to the monitor.

Light the copy stand properly. You may want to use a desk lamp, but make sure it doesn't shine into your eyes or onto your computer screen.

Improper posture during computer work also contributes to computer vision syndrome. Adjust your workstation and chair to the correct height.

Purchase ergonomic furniture to enable you to position your computer screen 20 to 24 inches from your eyes. The center of your screen should be about 10 to 15 degrees below your eyes for comfortable positioning of your head and neck.

10. Consider computer eyewear.

For the greatest comfort at your computer, you might benefit from having your eye care professional modify your eyeglasses prescription to create customized computer glasses. This is especially true if you normally wear contact lenses, which may become dry and uncomfortable during sustained computer work.

Computer glasses also are a good choice if you wear bifocals or progressive lenses, because these lenses generally are not optimal for the distance to your computer screen. Also, you may want to consider photochromic lenses or lightly tinted lenses for computer eyewear to reduce your exposure to potentially harmful blue light emitted by digital devices. Ask your optician for details. AAV

COMPUTER EYE STRAIN? Find an eye doctor near me. >

COMPUTERS AND CONTACTS Office worker rubbing his eyes while sitting in front of a computer

Do Contact Lens Wearers Have More Computer Vision Problems?

Because so many computer users wear contact lenses, researchers in Spain reviewed published studies to see if contact lens wear increases the risk of computer vision problems or causes a worsening of computer vision syndrome.

The investigators found 114 studies written in English or Spanish and published from 2003 to 2013 that referenced both contact lenses and computer use. They chose six studies for final analysis.

All six revealed that contact lens wearers were more likely to have computer vision syndrome symptoms than individuals who wore eyeglasses only or did not need corrective lenses. Prevalence of symptoms ranged from 17 to 95 percent among contact lens wearers and 10 to 58 percent among non-wearers. Also, contact lens wearers were four times more likely to have dry eyes during or after computer use, compared with non-wearers.

Silicone hydrogel contact lenses were associated with more comfort than regular soft lenses among computer users.

The study authors concluded that, during computer use, contact lens wearers suffer more eye discomfort and visual disturbances than non-wearers. But they also stated that, due to the small number of studies included in their analysis and the non-conclusive nature of some findings, more research is needed to determine the best type of contact lenses for computer users and how the lenses should be used.

A report of the study was published in the March/April 2014 issue of the journal Revista Espanola de Salud Publica.

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