Ever since smartphones burst onto the marketplace nearly a decade ago, making reading on the devices as attractive as talking into them, much has been said about their seductive power.
Psychologists describe those who hyperventilate after discovering they are missing their phones as having "nomophobia" (the fear of having no-mobile), and those who sense the buzzing of a new call or text — even when it didn't happen — are said to be plagued by Phantom Cell Phone Vibration Syndrome.
Comedians, too, love to mock the image of a solitary human gazing into the smartphone and asking Siri to define loneliness.
Yet for all the concern over smartphones and other mobile devices and their addictive potential, there may be more physical problems to consider: Staring at tiny screens, it turns out, is drying out our eyes, causing us to tense up our facial muscles, and even making some of us feel dizzy.
Doctors at the Massachusetts Eye and Ear Infirmary in Boston say they get a regular flow of patients complaining of sore eyes, blurry vision, headaches, and muscle strain — and only after consultations do they realize that it is related to excessive use of smartphones, among other computer devices.
"At least every eighth patient has this complaint — it's super common," said Dr. Matt Gardiner, an ophthalmologist at Massachusetts Eye and Ear and director of the hospital's ophthalmology emergency services.
Though scientists have introduced some inventions that can turn smartphones into reading aids, most people are at risk for the dangers these devices pose for their eyes.
Eye doctors say the most common problem is that people blink far less when their eyes are straining to read text on a small screen. Gardiner said people typically blink about 15 times a minute, but the average blink rate shrinks 50 percent or more when a person is staring into a smartphone screen.
"If they're very attentive, they tend to blink less," he said.
There are more than just dry eyes to consider. As people squint at their screens, their facial muscles contort in a way that can cause headaches. People also tend to stiffen their neck and shoulder muscles as they read from the small screens, which are often moving, even if only slightly, as they are held in the user's hands. This array of symptoms has been dubbed Computer Vision Syndrome.
Gardiner and others recommend some daily tips to make sure people get only the benefits — and not the physical drawbacks — of smartphone use. They include taking breaks every 20 minutes or so from staring at the screen, trying to blink more often, and increasing font size.
He also said that while he urges people to avoid prolonged reading on smartphones, they do not need to worry that long exposure to these devices is permanently hurting their vision.
Heavy smartphone users should also be careful to avoid too much reading in bed at night, as the blue light emitted from mobile devices can suppress the production of melatonin, which helps regulate sleep, clinicians say.
The latest iPhone operating system can also affect a person's sense of balance. Shortly after it was released, numerous users complained that the rapidly moving icons — that seem to zoom in and out with greater nimbleness than before — triggered dizzy spells.
Dr. Steven Rauch, an otologist and director of the clinical balance and vestibular center at Massachusetts Eye and Ear, said he is not surprised by such complaints given that people's sense of balance is achieved by the sensory inputs from the eyes, ears, and muscles. If any of these sense conflict — for example, your eyes feel as though you are moving because you are looking at zooming icons, but your body says you are standing still — you can feel momentarily unbalanced. For those prone to motion sickness, the unsteady feeling can get worse before it gets better.
Rauch said that if smartphone users start to feel queasy from using their device, they should simply close their eyes, look elsewhere, and try to reset their sensory system.
For all the problems smartphones can cause, the devices may be a boon for those who have trouble reading menus at restaurants or faraway signs at airports, providing more support than strain.
Gang Luo, an associate scientist at Massachusetts Eye and Ear, has created a free iPhone app, called SuperVision Magnifier, that helps magnify images and provide extra light by using the phone's camera. This app, among others available on the market, also has an "image stabilization" feature so that the enlarged type or images, such as from a menu or magazine, don't seem to move around.
He said he is also working on creating a device that could be attached to smartphones, enabling users to take photos of faraway signs, and then read the signs on the smartphone as if the sign had been nearby.
For those with serious vision problems, he is also working on an invention that would enable the smartphone, while placed in an individual's pocket, to send off an alarm if it detects the person is about to collide with something.
He said these proposed new uses of smart phones can be particularly helpful for people with limited distance or peripheral vision, such as those with macular degeneration and diabetic retinopathy.
Luo said he knows that society often focuses on the obsessive aspects of everyday smartphone use, but he and other scientists look at the technology as a way to enhance vision.
"In our field, we call it mobile computer technology," he said. "We think about it as a way to help people."
Patricia Wen can be reached at email@example.com.