US scientists today warned that squinting at a computer screen can cut in half the number of times the viewer blinks each minute, leading to a painful and irritating condition called dry eye.
According to a study conducted by researchers at Ohio State University, the
more that people 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 was found to reduce 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.”
Sheedy went on to explain that 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 realise 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.
Sheedy said that the next step is to work 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, but Sheedy stressed that neither he nor his co-authors have ties to the software firm beyond the scope of this study.
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