People who squint while staring at computer screens also blink less than normal, which dries and irritates their eyes, researchers said this week.
A study of 10 college students showed that the more they squinted, the less they blinked, the team at Ohio State University said.
The less they blinked, the more their eyes ached or burned, said James Sheedy, a professor of optometry who led the study.
All the students had perfect vision, and just a small amount of squinting reduced blink rates from 15 blinks a minute to 7.5 blinks a minute, Sheedy and colleagues reported in the journal Optometry and Vision Science.
"People tend to squint when they read a book or a computer display, and that squinting makes the blink rate go way down," Sheedy said in a statement.
"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."
People squint for good reasons -- it can make objects appear more clearly defined and it can cut glare. But blinking less dries the eyes and can irritate them, although the effects are temporary.