Squinting while staring at a computer monitor can cause painful dry eye

November 28, 2005

Squinting at a computer screen can cut in half the number of times someone blinks each minute. And that could lead to an irritating condition called dry eye, new research suggests.

The more that the participants in this study squinted their eyes, the less they blinked. And the less they blinked, the more their eyes ached or burned, and the more they reported sensations of dryness, irritation and tearing.

Just a slight amount of squinting reduced blink rates by half, from 15 blinks a minute to 7.5 blinks a minute.

“People tend to squint when they read a book or a computer display, and that squinting makes the blink rate go way down,” said James Sheedy, the study's lead author and a professor of optometry at Ohio State University. “Blinking rewets the eyes. So if your job requires a lot of reading or other visually intense work, you may be blinking far less than normal, which may cause eye strain and dry eye.”

Squinting serves two purposes: It improves eyesight by helping to more clearly define objects that are out of focus. It also cuts down on the brightness from sources of glare. It may be voluntary or involuntary – a person working at a computer may not realize that he is squinting.

Dry eye is usually treatable with over-the-counter eye drops. It's rarely a debilitating condition, but it can be irritating and painful.

The results appear in a recent issue of the journal Optometry and Vision Science. Sheedy conducted the study with Ohio State colleagues Sowjanya Gowrisankaran, a graduate student, and John Hayes, a research scientist in optometry.

The researchers asked 10 college students to squint at different levels. All participants had 20/20 vision in both eyes. The researchers attached two tiny electrodes to the lower eyelids of each student. The electrodes were also attached to an electromyogram, a machine that records the electrical activity of muscles. In this case, the researchers wanted to record the action of the orbicularis oculi muscle, which encircles the eye socket and allows the eye to both blink and squint. The electromyogram measured the different degrees of squint.

The researchers also videotaped the blinking students.

Participants were situated in a chin and forehead rest – doing so let them relax their head and neck while squinting at the various levels. Subjects were asked to look directly at a computer screen situated about two feet in front of their eyes.

The researchers recorded data from five trials. For the first trial, participants were asked to completely relax their eyes. For the next four trials, students squinted in increments ranging from 5 percent (barely squinting) to 50 percent (eyes closed about half-way.)

Participants were also instructed to continuously look at a black dot in the center of a computer display. They listened to music while a changing pattern, which was driven by the music, moved around the black dot.

At the end of the trials, the researchers watched the videotapes and counted the number of times each student had blinked during the trials.

Blink rates decreased from an average of 15 blinks per minute when the eyes were relaxed to 7.5 blinks a minute when students squinted just 5 percent. That number was reduced to four blinks a minute when participants squinted at the 50 percent level.

Sheedy said that the next step is to figure out the physiological mechanisms behind eye strain and dry eye.

“The neural pathways leading to eyelid blink aren't completely understood,” he said. “And the mechanisms controlling blink seem numerous and complex.”

Source: Ohio State University

Explore further: 6-year-olds with squint less likely to be invited to birthday parties

Related Stories

Genetic mutation identified for eye complaint

July 24, 2008

An international research collaboration including research teams from the Children's Hospital in Boston (USA), King's College London and the Peninsula Medical School, has identified a gene that, when mutated, causes Duane ...

The Medical Minute: Pediatric eye safety

July 29, 2010

Yes, the dog days of summer are upon us; for most families that signals the longstanding tradition of back to school preparation. It’s time to begin the search for the perfect backpack and notebook, shop for new clothing ...

3-D advances come with health concerns for children

January 12, 2011

In a seeming blink of an eye, 3-D technology has advanced beyond imagination. Hollywood, TV manufacturers and video game makers say you have to see it to believe it. But the visual trickery that produces 3-D images can also ...

Leicester breakthrough in eye disease

December 13, 2006

Researchers at the University of Leicester have identified for the first time a gene which causes a distressing eye condition. Their discovery, as reported in the journal Nature Genetics, is expected to lead to better treatments ...

Recommended for you

'Material universe' yields surprising new particle

November 25, 2015

An international team of researchers has predicted the existence of a new type of particle called the type-II Weyl fermion in metallic materials. When subjected to a magnetic field, the materials containing the particle act ...

CERN collides heavy nuclei at new record high energy

November 25, 2015

The world's most powerful accelerator, the 27 km long Large Hadron Collider (LHC) operating at CERN in Geneva established collisions between lead nuclei, this morning, at the highest energies ever. The LHC has been colliding ...

New gene map reveals cancer's Achilles heel

November 25, 2015

Scientists have mapped out the genes that keep our cells alive, creating a long-awaited foothold for understanding how our genome works and which genes are crucial in disease like cancer.

A blue, neptune-size exoplanet around a red dwarf star

November 25, 2015

A team of astronomers have used the LCOGT network to detect light scattered by tiny particles (called Rayleigh scattering), through the atmosphere of a Neptune-size transiting exoplanet. This suggests a blue sky on this world ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.