Computer use and Dry Eye Syndrome

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Category: Eye Health/Ophthalmology News

Article 29 Nov 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. "

 

This study was supported by a grant from Microsoft Corp. Neither

Sheedy nor his co-authors have ties to Microsoft beyond the scope of

this study.

 

Written by Holly Wagner

 

James Sheedy

JSheedy

Ohio State University

http://researchnews.osu.edu