Do just about anything too long and too intensely and you’ll feel the burn. Do it with your eyes while using an electronic screen and that burn will probably develop into what the American Optometric Association calls a “close work-related compound eye problem” — that is, computer vision syndrome (CVS).
“Try reading one page in a book on your lap and then raise that same book up to eye level and read one more page,” says Viola Kanevsky, OD, president of the New York State Optometric Association and an optometrist in private practice in New York City. “You’ll feel your eyes start to burn within a short period. Now, multiply that by eight hours a day while adding in poor hydration, contact lenses, and, possibly, a mask that keeps you from drinking adequate amounts of water and causes you to breathe up into your eyes.”
“That,” she continues, “is CVS.”
Also known as digital eyestrain, some degree of CVS is shared by an estimated three-quarters of all computer and smartphone users who spend four hours or more a day on their devices. With the number of regular internet users set to reach five billion worldwide by midyear, according to DataReportal, and the “typical user” devoting seven hours daily to the habit (per GWI), you’re probably experiencing CVS from your online hours alone. Add in your other electronic screen–based tasks, and CVS is almost unavoidable.
Fortunately, there’s a happy flip side to the unhappy discomfort CVS can cause: The condition doesn’t seriously damage the eyes and is almost entirely preventable.
What Causes CVS?
Ophthalmologist Peter K. Kaiser, MD, director of the Cleveland Clinic’s Center for Ocular Research and Evaluation (CORE), in Cleveland, sees the fault in the screens.
“First, when you stare at the screen, your blinking slows, which tires and irritates your eyes,” Dr. Kaiser says. “Second, the color spectrum of most monitors shifts towards the blue, which affects parts of the brain that control awakeness and sleep, as well as melatonin levels.” By interfering with melatonin production, he explains, blue light can make it more difficult to sleep. Lack of sleep can reduce tear production, which in turn can adversely affect your eye health and comfort.
And that’s just the beginning.
Mark Rosenfield, OD, PhD, a professor of biological and vision sciences at the State University of New York College of Optometry in New York City, has found that the degree of CVS distress may be directly proportional to the difficulty of the content being processed. It’s not blink rate, but completeness of the blink that counts, he adds.
“We’ve done studies showing that with demanding work, your eyelids will not come fully together when you blink,” says Dr. Rosenfield. “That leaves enough of the eye’s surface open to the air to cause drying.”
Duration of screen time seems to up the eye irritation ante. A report published in September 2021 in the Journal of Health Education on CVS among academics revealed, for example, that among those who’ve been heavy computer users for upwards of five years, the CVS risk is 18 times greater than among their counterparts with fewer than five years of heavy electronic use.
Complicating this are the unpleasant effects wrought by poor lighting, improper computer positioning, dry indoor air, wearing the wrong prescription glasses, contact lens overuse, and poor posture.
Symptoms of CVS
An equal opportunity offender, CVS came home with the first personal computers. The condition’s prevalence and severity soared with the debut of the internet and, later, smartphones.
Today, CVS’s symptoms fall into four broad categories:
Ocular (Eye) Symptoms A sandpapery feeling, excess watering, the sense of having a foreign body in the eye, a burning sensation, and achingly dry eyes are among the hallmarks of CVS. Failing to ensure adequate humidity, lighting, and a sufficient number of rest periods worsen the problems.
Vision Effects Blurring, sluggishness in changing focus, double vision, and heightened presbyopia are transient effects of electronic overuse. (Presbyopia is the inability among people, predominantly those age 40 and older, to clearly see objects at close range.) More troubling consequences, though, can target children as young as age 2.
“For children, using electronics excessively can increase the incidence of nearsightedness, which has almost reached epidemic levels in most countries,” says Kaiser.
Recently, researchers have blamed a COVID-related increase in near-to-hand activities and a decrease in exercise and other outdoor activities for the significant rise in childhood myopia. Indeed, an editorial written by Rosenfield and published in March 2022 in Ophthalmic and Physiological Optics, the Journal of the College of Optometrists, suggested that lifestyle changes ushered in by the pandemic are responsible for “a dramatic increase in the prevalence of myopia, particularly in studies emerging from China.”
RELATED: What Is Myopia (Nearsightedness)? Symptoms, Causes, Diagnosis, Treatment, and Prevention
Extraocular, or Problems Outside the Eye Sitting at a computer screen or hunched over a smartphone or iPad can lead to headaches, neck pain, back pain, and shoulder pain. Poor posture, clenched muscles, and inactivity all contribute to these CVS-related problems.
What You Can Do Now to Ease or Avoid CVS
The CVS cloud, though, has its own silver lining. Given the right preparation, some easy-to-achieve strategies, and a commitment to eye health, even the computer-addicted can counteract CVS.
Electronic screens are insidious in taxing the eyes in several ways, some of which can be addressed with a change in settings or in the work environment. Glare, the brightness of the light coming from the screen — or competing with it from a nearby light source — can tire the eyes. So, too, can poor resolution; that is, the lack of clarity or fuzziness of on-screen images. Poor contrast — the way in which individual images within the screen are clearly differentiated from each other and from the background — can force the eyes to work harder.
Add to these sources of eye fatigue the blue light emitted by the computer itself. Many researchers agree that over extended periods, this high-energy illumination can contribute to digital eyestrain. When it’s allowed to disrupt the body’s sleep-wake cycle, and thus normal tear production, blue light may lead to other vision problems as well.
What can you do about this? Plenty. Here are some suggestions:
Adjust the Electronics: Keep the Screen Below Eye Level
Positioning a monitor too high is a CVS red flag, as is sitting too close to a screen. That too-close-for-comfort approach forces the eyes to open wider than the natural “half-mast” position assumed when reading a book. “The position of the monitor is a huge factor,” says Dr. Kanevsky.
She suggests ensuring that the top edge of a monitor is at least 15 to 30 degrees below the horizontal line of sight, with the center of the screen located between 4 and 6 inches — 10 and 15 centimeters (cm), and 15 to 20 degrees — below the straight-ahead gaze. If the monitor’s top edge exceeds eye height by as little as 10 cm, or almost 4 inches, it’s more likely to worsen CVS symptoms.
“Under normal conditions, as in reading a book on your lap, you’re looking down with the eyelid covering three-quarters of the ocular surface,” Kanevsky says. “So even if you aren’t blinking as frequently to rewet the eye, there’s only a small exposed area of the eye, limiting the amount of tear film that can evaporate.”
By contrast, when the screen is brought higher and the eye is wider open, more of its surface is exposed to evaporation. “That’s important,” she says, “because complete blinks not only rewet the cornea, but they squeeze the glands inside the lids, releasing oils that keep those tears from evaporating.”
In addition, if people are wearing bifocals or progressive spectacles, they must tip the head back to put reading material in the bottom half of the glasses. This can cause neck sprains or cramping.
Maintain a Healthy Distance
Studies confirm that changing the distance from the monitor to the eye can make illumination of the screen more palatable. Compare a flashlight held inches from your eye to one held 5 feet away. The light, passing through the intervening distance, has more time to scatter and degrade when the separation is greater. That’s true of electronic screens, too.
Some researchers, such as in a paper published in January 2018 in the Journal of Eye and Vision (PDF), call for locating the screen between 1.31 and 2.46 feet (40 and 75 cm) away from the user. Others, such as in an article published in October 2020 in the Nepalese Journal of Ophthalmology, set the desired gap at 20 to 25 inches (50.8 to 63.5 cm). Either way, distance promotes eye health, while closer monitors heighten eyestrain.
Revisit Resolution and Font Size
Improving the screen resolution to sharpen the display is helpful and easily accomplished.
On Windows 10 and 11, close all programs, restart the computer, click on the Control Panel followed by System and Display. Select a higher resolution from the drop-down menu. Click “Apply” and “Keep Changes” to save the new setting.
For Apple devices, select System Preferences, Display, and then choose the desired resolution from among the options.
Remember, though, that changing the resolution can shrink the font size, the size of the individual letters. That’s why you may need to change to a larger text size when altering resolution.
Consider adjusting resolution and font settings on your mobile phone, too.
Diminish Brightness and Glare
Glare is obviously irritating and eye-squint fatiguing. So are some kinds of high-energy blue light (HEV). The shortest visible light wavelength emanating from computers, HEV can tax the ciliary muscles that control the shape of the eye’s lens, as well as the eye’s photo-receptor cells.
Switching to a friendlier sepia or yellowish shade can help dial down the level of glare coming from a device’s background illumination. Most computers are readily equipped to accept the adjustment.
On Apple devices, right-click on the desktop, select the “Display Settings” option and turn on the “Night Light” switch.
Similarly, on Windows computers, open System Settings (Display, Notifications, and Power), select “Display” and turn “Night Light” to the “On” position.
Consider Using a Screen Filter
Although the use of blue light filtering screens to reduce the amount of high-energy light is controversial, many medical professionals see real value in adding an anti-glare filter.
As the University of Rochester Medical Center in Rochester, New York, advises, these filters can enhance screen contrast and make characters easier to read, while often also serving as privacy screens. The filters are widely available for under $100 and fit a variety of screen sizes.
When you find yourself truly absorbed in a task, it’s easy to stare, which leads to less reflexive blinking. When the task involves a computer, the blink also tends to become less complete, putting the surface of the eye at more risk for dryness.
“Normally, when the upper lid wipes the front of the eye as it comes all the way down to meet the lower lid, it functions like a vertical windshield wiper to evenly spread a layer of tears across the eye,” says Rosenfield.
Researchers aren’t sure why computer time disrupts this normal blinking function, but Rosenfield speculates that the brain, forced to work harder at the computer, unconsciously minimizes the amount of time the eye is closed. That spark of additional time enables the brain to gather as much information as possible without interruption.
He also questions whether some novel solutions for the dysfunctional blinking — from “blink alarm” smartphone applications that warn of too-infrequent blinks, to spectacles that fog up after five blink-less seconds, eliciting an immediate blink — are not only useless, but potentially counterproductive.
“When we studied blink alarms, we found that people were so distracted by waiting for the tone or alarm on their smartphones to go on that they couldn’t finish what they were doing and became annoyed,” Rosenfield says.
Kaiser agrees. “You don’t need a special alarm,” he says. “You just need to regularly get up and blink.”
Have Your Vision Correction Checked Regularly
So-called computer glasses may ease the discomfort of CVS. These aren’t the same as glasses that block blue light, but rather are prescription glasses calibrated to deliver optimal focus at the optimal distance (20 to 25 inches) from your electronic device.
Many vision professionals, however, say the biggest cause of vision correction fatigue — wearing the wrong prescription — can be resolved only by scheduling a full eye exam.
“You don’t necessarily need special glasses to work at a computer, but you do need to discuss the best lens with your doctor,” says Rosenfield.
Some clinicians maintain that also harmless, but unnecessary for CVS patients, are the blue-blocking spectacles crowding the vision marketplace.
“A very common misconception is that blue-blocking glasses are an easy fix, but there’s little evidence that they do much more than help those with chronic migraine or patients suffering from post-concussion syndromes,” says Kanevsky.
And while Kaiser allows that some blue-blocking specs may slightly slow cataract progression for some patients, he says that “the glasses don’t seem to do much otherwise.”
Indeed, existing studies suggest that though blue light glasses may help prevent disrupted sleep, they don’t directly protect against any kind of eye damage.
That said, Kaiser and other medical experts suggest skipping contact lens use when you have a serious day with your electronic devices. Contacts tend to promote dryness (already a CVS hazard), while spectacles carry little such risk.
RELATED: Do Blue Light Glasses Work? A Scientific Look at Their Possible Benefits
Improve Your Working Environment
The ambient lighting in your office or home should approximately equal the brightness of your screen (that is, one shouldn’t be brighter than the other), since the blink rate slows in dark settings.
Bright overhead lighting is best kept to a minimum, and desk lighting should be pointed away from the user. It’s also helpful to ensure that natural light from the outdoors originates from alongside, rather than in front of or behind the computer user.
Good posture, of course, is essential. Sitting up straight, without hunching shoulders or curling the neck, helps diminish CVS’s muscle cramps and headaches.
Limit Children’s Exposure to Screens
It’s tough to definitively link computers with nearsightedness in children, but there is strong circumstantial evidence, including a report published in 2021 in the British Journal of Ophthalmology that linked a possible increase in the incidence of myopia among youngsters with the pandemic. The report’s authors suggest as the culprit the simple fact that online time has soared while outdoor time has plummeted during the outbreak.
That finding was among several observations prompting JAMA Ophthalmology, in a March 2021 editorial, to label 2020 “the year of quarantine myopia.”
Computers are risky enough, but smartphones may pose the bigger threat for children. The shortened distance between the screen and the eyes, the relatively poorer screen resolution, and the less-readable text on hand-held devices all add up to heightened risk of eyestrain. (And operating a smaller screen almost invariably leads to poor posture.)
Environmental factors — dry air, ventilation fans, static build-up, dusty environments, and windy weather when outdoors — accelerate drying, a process that irritates eyes. Be sure to keep liquids handy and hydrate frequently. If possible, set a humidifier near wherever you work. Don’t hesitate to instill preservative-free, over-the-counter drops at the earliest signs of burning or discomfort.
“These drops can be used as often as you need them without any problem,” says Kaiser.
For those whose dryness has progressed to dry eye disease, an ophthalmic evaluation should be performed, after which prescription eye drops or nasal spray may be recommended.
RELATED: Dry Eye Disease (DED) Is Now Rampant. What Do You Need to Know to Control It?
Take Breaks and Move Around
For children and adults alike, the 20-20-20 rule remains gospel.
“Every 20 minutes, take a 20-second break to look at something 20 feet away, and blink,” Kanevsky explains. “Even better, spend 20 minutes standing and then 20 minutes sitting while keeping the screen low and angled up toward your eyes, like a book.”
The American Optometric Association also recommends that long-term computer users schedule 15 minutes away from the screen after every two hours of continuous use.
Also consider pounding the pavement during your short hiatuses. A study published in January 2022 in BMC Ophthalmology about dry eye disease strongly connected aerobic exercise with improved tear film stability. The report envisions aerobic exercise as a “potential treatment for dry eye.”
Rosenfield says that he believes it’s the time away from the screen, not the exercise, that has the greater curative power.
Finish Your Screen Use Early
If at all possible, don’t take your electronic session all the way to the finish line, aka bedtime. Nor should you bring the smartphone into your bed, since it can lead to a night of tossing and turning. Instead, observe the standard rules of sleep hygiene by eschewing all screens in the bedroom, and keeping your nightly repose dark, quiet, and peaceful.
The Good News: No Long-Term Damage
With the right precautions and intelligent limits, the symptoms of CVS usually resolve quickly. And, as Kaiser points out, no lives have been lost to this increasingly common condition.
“Computer vision syndrome doesn’t have to lead to any long-term problems other than irritation,” Kaiser says. “The only thing that will happen, even if you neglect your CVS, is that your eyes will hurt. But that can be aggravating enough.”