As a child, your mother always said: “Don’t sit so close to the TV, or you’ll go blind!” But now almost everyone who works at a desk spends their entire day staring at a screen from distances that are most definitely not “mom-approved.”
Do all those hours spent staring at your personal glowing portal to the digital world have an effect on your eyesight? Recent studies show that Mom might have known a thing or two after all. Eyestrain has also been linked with an increased risk of glaucoma. The human visual system is complex and amazingly adaptive. It can change focus to see objects both near and far. It can change to see in bright conditions or dark conditions. With the help of 140 million neurons in the visual cortex it can identify, classify, analyze and react to approximately 12 to 15 one-million-point images per second. Yet, despite this complexity, human eyes just don’t handle extended computer screen viewing all that well. “Your eyes are happiest when used for a variety of tasks utilizing a variety of focal distances with a variety of properly aligned light sources,” states Jeffrey Anshel, O.D., author of Visual Ergonomics in the Workplace. “Computer use provides none of the above.”
Strain on the eye from computer use comes from a several sources. The first is a constant working distance typical of computer users. Two sets of muscles work in tandem to see your screen clearly. One set converges the eyes onto the same point. The other set actually flexes and fattens up the crystalline lens in each eye to properly focus light rays from the computer onto the retina. As with any muscle in the body, continuous flexing can create repetitive stress problems. Ever have blurred vision when looking away from the screen? This may be a spasm of the ciliary muscles causing focus to “lock,” thereby creating a temporary loss of distance vision. Other symptoms may include blurred vision, the inability to properly focus on the screen, or even a good old-fashioned headache. Ever find that your eyes have an irritated “scratchy” feeling after a long session using the computer? A relatively normal blink rate is 12-15 blinks per minute, but computer users tend to blink much less frequently, more typically around 4-5 blinks per minute. Why? The eyes normally jump around the screen in pattern called a “saccade.” Blinking disrupts this pattern and lowers productivity for someone concentrating on an intense visual task, especially when under deadline to get a big project done. Blink less and you get more done… but it can take a toll on your eyes.
