by Dr Shabbir Saifuddin
If you already wear regular glasses or reading glasses, you may be tempted to just dismiss the idea of computer glasses outright. Unfortunately, your regular glasses are not quite right for computer work. Why? Most people wear glasses that do not correct the intermediate zone at all: Reading glasses correct near vision only, and bifocals correct only near and far. Even those that do correct the intermediate zone have only a small portion for the intermediate area, not nearly large enough for comfortable computer work.
Without appropriate eyeglasses, computer users end up with blurred vision, eyestrain and, often, headaches. Worse still, many people try to compensate for their blurred vision by leaning forward, or by tipping their head to look through the bottom portion of their glasses. Both of these actions can result in a sore neck, sore shoulders and a sore back.
Recent studies support the notion that computer eyeglasses can increase productivity and that even a slightly inaccurate prescription can decrease it. A study examined the vision of computer users aged 19 to 24 before and during performing tasks that required them to read fonts of various sizes on a computer screen. Some subjects wore corrective lenses, while others wore non-correcting lenses; the lenses were randomly assigned. Researchers timed the tests and recorded the number of errors the subjects made, then had them answer questions about the vision problems they had experienced.
It was found that even when symptoms were not reported and the computer screen was seen clearly, there was a differences in productivity and accuracy over time. The greater the miscorrection, the greater the decrease in productivity. Yet, even when the subject's vision was slightly off, productivity was significantly affected. A difference of just 0.5 diopters from the correct lens prescription resulted in an average 12 percent loss in productivity and a 45 per cent decrease in accuracy.
Computer lens designs
One of the more popular types of computer eyeglass lenses is the occupational progressive lens, a no-line multifocal that corrects near, intermediate and, up to a point, distance vision. It has a larger intermediate zone than regular progressive lenses, leaving less space for distance. So, while you would be able to see well enough in the office (most allow you to see a distance of about a room's length), the lens tends to be poorly suited for regular wear.
Another option is a lined trifocal, with a larger intermediate zone than regular trifocals (again, making them a poor choice for non-computer wear).
Some people need only a bifocal, either with intermediate and near correction, or intermediate and far. Others find they can get by with just a single-vision lens (intermediate) that they use for computer work only.
Computer prescriptions are also available in clip-ons that attach to regular eyeglasses.
Another benefit: Eyestrain relief
In addition to fixing your blurry vision, computer glasses can help with another problem as well: Eyestrain from bright office lighting. Getting anti-reflective coating on your lenses can significantly reduce the amount of glare and reflected light that reach your eyes. It's a must that all computer users must have anti-glare coating on their lenses. Even plain glasses with anti-glare coating can reduce strain on eyes by 40 per cent.
If your office has fluorescent lights, you might want to consider two other options as well -- fluorescent lights emit a great deal of blue light, which makes it difficult for the human eye to focus due to (blue light's) scattering characteristics. Ultraviolet coating can cut down on the amount of blue light that reaches your eyes, as can an amber tint.
(Dr Saifuddin is an eye specialist with Al Musallah Medcial Centre, Bur Dubai and Jansons Medical Centre, Bur Dubai.)