It's possible to sit in front of a computer for eight hours at work, watch a movie on a cell phone during the train ride home, surf the Net for 90 minutes after dinner and text message all day.
It's enough to suck the nation's eyes dry.
Doctors say there is too much staring and not enough blinking, and it is resulting in an annoying condition the American Optometric Association terms "computer vision syndrome."
The syndrome is not one defined disorder but a collection of symptoms that is affecting people young and old who work, study and play in front of a screen. Industry officials believe it's more widespread than repetitive motion injuries, such as carpal-tunnel syndrome.
"I ask about it as part of my [patients'] history when I do an exam now," said Martin Novey, a doctor of optometry for Katzen Eye Group in Lutherville. "Out of my patients who use computers, two-thirds have some symptoms. There's a lot of eye strain."
The optometric association says 82 percent of respondents in a recent nationwide survey say they frequently use a computer or hand-held device, and 42 percent frequently use them for three or more hours a day.
Most do not blink enough or take enough breaks, their lights are too bright and their computer screens are positioned incorrectly. As a result, up to three-quarters of the computer users report eye problems, according to the Journal of the American Optometric Association, and 10 million primary eye-care examinations are conducted each year because of computer-related problems.
Another survey conducted by the Vision Service Plan insurance company shows that 90 percent of school-age children use computers daily, and they spend one to three hours on the Internet each day.
And while their eyes cope better than adults, especially those older than 40, the eyes of children, too, are showing signs of trouble, Novey said. Some may need glasses sooner.
Eye doctors say the syndrome generally does not cause permanent damage. But during March, which is Save Your Vision Month, they are trying to explain that a few steps can alleviate a lot of discomfort.
In addition to dry eyes, typical symptoms of computer vision syndrome are burning eyes, blurred vision, fatigue, headaches and neck and back pain.
Latrella Williams said her eyes were always tired and a little blurry by the end of her night shifts on a computer at Mercy Medical Center in Baltimore. The healthy 38-year-old, who doesn't wear glasses, assumed the problems came with the job.
So did Cheryl VanKuren, director of operational management at Union Memorial Hospital. She's on her computer or her BlackBerry all day. She also has allergies and wears contact lenses. It can be a potent mix during a long workday, and sometimes her eyes feel strained or tired.
VanKuren has already increased the font size on her hand-held and made the type bold so that she doesn't have to squint as much to see what's on the small screen. Both patients of Dr. Novey, they also learned during recent screenings that they can do such things as use over-the-counter eye drops, adjust light away from their screens and take frequent breaks.
Novey also said they could order glasses that magnify words and reduce glare.
"I was taking the symptoms in stride, ignoring them really," VanKuren said. The doctor visit "made me more aware. I'm now paying more attention to the fatigue and eye strain and dry eyes."
Colleen Halfpenny, an ophthalmologist and cornea specialist at the Krieger Eye Institute at Sinai Hospital, said dry eyes are the biggest complaint of computer users.
She said people who use computers blink a third less than they would normally, and that leads to more tear evaporation and more dryness. Dry eyes can also cause the screen to seem blurry.
Computer and hand-held users should be conscious of blinking more. They should also position their screens so they are looking slightly downward on them so their eyelids can close more and prevent some tear evaporation.
Eye doctors also say computer users should avoid glare on the screen from lighting. They suggest lowering the lights in the room so that they are not brighter than the terminal, angling light fixtures away from the screen and closing window blinds.
Some doctors didn't think glare guards or special screens atop computer monitors were especially helpful for most. They said something called 20-20-20 works better - looking up from the screen every 20 minutes for 20 seconds at something 20 feet away.
But sometimes, all the staring means that users also have a hard time focusing on something in the distance. Normally, eyes are working hard when they focus on something close and relaxing when looking at something farther away, Halfpenny said. Relaxing gets tougher for people who stare too long at a screen, especially for older people with some natural deterioration.
"When the screen looks blurred, that's from dryness," Halfpenny said. "When something far off looks blurry it's because you've not looked far away in a while, and it take some extra time for your eyes to relax and accommodate the change."
Novey said heavy use of technology by children has meant they, too, are increasingly having trouble focusing.
Cell phones and other hand-held devices are easy to hold lower and shield from light, often making them easier on the eyes. Users also tend to naturally look up from them more if they are moving around. But the small screens make the eyes work even harder, he said. For some children, it may result in premature myopia, or nearsightedness, where objects at a distance are blurred, he said.
He said parents need to observe their children, make sure they take breaks and limit their daily computer use. And while healthy adults should have an exam every two year, children should be checked every year.
"A good night's sleep relieves most of the symptoms," Novey said. "However, there are studies that show there can be lasting effects with children. ... With adults, we tend to find a loss of production in the workplace. Everyone should be aware."
Tips to prevent eye strain
Blink often. Take a break from the computer for 20 seconds every 20 minutes and look at something 20 feet away. Use drops when needed.
Look down on the screen. Adjust your chair, computer or hand-held so that you are looking slightly downward, about 10 to 15 degrees.
Sit back. Sit at least 18 inches from your computer screen, and increase the font size if you can't read easily.
Reduce glare. Adjust light sources away from the screen, and reduce the room's light so that it is not brighter than the screen.
Get examined. Have your vision checked for the proper prescription every two years. Children should be checked every year.
[Source: American Optometric Association]
Computer vision syndrome
The syndrome is the common collection of vision problems related to computer use. Symptoms include dry eyes, eye strain and fatigue. It can decrease performance, and it occurs in up to three-quarters of people who work on computers. A survey of optometrists revealed that 10 million exams are done every year primarily because of computer-related problems.
[Source: American Optometric Association]