This is demanding-and tiring-for the poor little muscle. Staring closely at a screen forces our ciliary muscle, which controls the shape of our lens and therefore how well we focus, to remain contracted, without rest. This innermost layer at the back of the eye is responsible for collecting and then moving light information, via the optic nerve, to the brain, which produces an image. The cornea and the crystalline lens (a transparent, round, flexible structure behind the iris) then bend the wavelengths so they hit the rods and cones-photoreceptors on the retina that gather incoming light information. When we "see" something, light reflects from an object through the cornea, the transparent, dome-shaped layer covering the eye. The simplest way to understand why eyestrain develops-and learn how to prevent it-is by looking at the way our built-in binoculars show us the fine print. Such activity causes eye exhaustion: burning, dryness and muscle aches-all unpleasant and potentially incapacitating symptoms while they last. Though for most it is not permanently damaging, computer near work leads to an uncomfortable, at times debilitating, list of symptoms collectively known as eyestrain.Įyestrain, says Mark Bullimore, a professor at The Ohio State University College of Optometry, results from staring at a screen over long periods of time. The fact that near work doesn't lead to myopia in all of us, however, doesn't mean sitting close to a computer screen causes no problems. "We are not very clever in identifying who yet," says James Sheedy, a professor at the Pacific University College of Optometry in Oregon. Staring at a computer screen qualifies as well, though monitors usually are around 50 centimeters (20 inches) away.īut only a small-and mysterious-subset of people see myopic progression from near work, whether they are focusing on a computer or accounting books.
Ophthalmologists, optometrists and other eye professionals note a seeming link between myopia, also called nearsightedness, and "near work"-visual activities that take place at a distance of about 40 centimeters (16 inches) from the eye-such as reading a book. At this point, you need to know: With each further click on the keyboard, video watched on YouTube, and e-mail sent-are you damaging your vision? Despite the brief reprise your vision remains cloudy, causing the words on the monitor to blur. After rubbing them you settle back into staring, hunched inches away from the computer screen. You roll your head, hoping to loosen the knots in your neck, and shut your eyes.
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