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June 1, 2010

Squinting helps the eyes focus fuzzy images.


Focusing on a fuzzy question…I’m Bob Hirshon and this is Science Update.

Today’s Why Is It question comes from nearsighted listener Tom Grydeland of Tromsø, Norway. He wants to know why squinting helps him see more clearly without his glasses. We asked Pia Hoenig, chief of the binocular vision clinic at the University of California at Berkeley’s School of Optometry. Hoenig says rays of light come from all directions into the eye, and the ones coming from the periphery don’t get focused as well onto the retina. Squinting helps by creating a pinhole effect.

PIA HOENIG (UC Berkeley):
Then you take away some of those lines of sight that is coming from the periphery.

Like in a camera, reducing the size of the aperture increases the depth of focus, ensuring that the image lands on the retina instead of in front of it. If you’ve got a science question, call 1-800-WHY-ISIT. I’m Bob Hirshon for AAAS, the science society.