Do you experience eye-strain, fatigue and muscle tension when using your computer? You may be wearing the wrong glasses or the screen may be too close.
Most of us spend a lot of time working at our computers. This means we’re looking at a screen for most of the time. The usual distance from eyes to screen is around 60 cm.
Normal reading glasses are designed to be used at an optimum reading distance of 30-40 cm. In other words, reading glasses are not designed to be used for the distance from the screen. It follows that when you use regular reading glasses for computer work you are actually straining your eyes. This will most likely lead to a worsening of your vision and, consequently, the need for even stronger reading glasses. If you must use reading glasses for computer work, they should be fitted for the distance to your screen.
There is another important vision function involved here–the natural resting point, which is the position at which there is no visual input. For example, at night your eyes will find a resting point from where there is no effort in converging ordirecting your eyes. This resting point is normally about 50–80 cm away from your eyes. If your resting point coincides with the position of your screen, then there is very little effort involved in looking at your screen. However, when the resting point is in front of or behind the screen, you have to constantly use muscle power to force your eyes to converge on the screen. This, of course, leads to fatigue, eyestrain and eventually headaches. For this reason, the best position for the screen is as far away from you as possible. Research shows that you make fewer mistakes when the screen is one meter away than when the screen is closer.
To sum up. Firstly, glasses for computer use should have a lens power that gives you optimum vision at the distance of your computer screen, not for the visual distance you need for reading a book. Secondly, the convergence –the centre-point of the lenses –should be at the computer screen distance and take into account that your angle of sight is on the screen. In this way, there will be a minimum of stress on your eyes.
Often optometrists do not take enough time to take all these measurements meticulously. If the centre of the lens is off by even a millimetre, the plus lenses become prisms that will further strain your eyes while reading. Furthermore, the angle at which you view your screen should also be taken into account. Your near point of clear vision becomes closer as the reading angle moves downwards. If the computer screen is straight ahead of you, your computer lenses should be fitted so that you get optimum vision when looking straight ahead. In other words, the centre of the lens should be right in front of your eyes when you are looking at the screen. Off-the-peg glasses are designed for reading books only.
Bi-focal or multi-focal lenses require you to turn your head upward in order to look through the right portion of the lens. Holding this position for long periods of time may lead to neck and shoulder tension or pain.
The above article was excerpted with permission from Leo Angart’s book, “Read Again Without Glasses.” Leo teaches ‘Throw away your glasses’ workshops all around the world.
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