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23 November 2010

Eyestrain

Eyestrain is a common form of eye discomfort that can occur when the eyes tire after you have been doing a particular visual task for a prolonged period,

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Summary 

  • Eyestrain is eye discomfort that occurs when the eyes tire after doing a particular task for a prolonged period.
  • Causes of eyestrain include focusing the eyes for a prolonged period on a fixed object, poor lighting and glare.
  • Eyestrain is a common problem for people who have to focus close-up for long periods.
  • Symptoms include headaches, painful or uncomfortable eyes and vision problems.
  • Eyestrain can usually be relieved or prevented by organising your workstation for visual efficiency and by taking vision breaks.

What is eyestrain?

Eyestrain is a common form of eye discomfort that can occur when the eyes tire after you have been doing a particular visual task for a prolonged period, such as spending several hours at the computer.

Eyestrain refers to headache or discomfort around the eyes. These symptoms are never present when you wake, never accompanied by ultra-sensitivity to light, but is made worse by visual tasks like reading. In most cases you may just need a new pair of glasses or contact lenses, or the muscles that align the eyes are strained and need a break.

What causes eyestrain?

The causes of eyestrain include:

  • Focusing the eyes for prolonged periods on a fixed object, especially one that is held close to the eyes. The eyes are designed to shift focus between near and distant objects and extended focusing on a single object can cause eyestrain. Eyes are strained more by close viewing than by distant viewing.
  • Poor lighting. Doing close work in poor light forces your eyes to focus under difficult conditions.
  • Glare, either direct or reflected, makes it difficult to see. Direct glare is when a light source shines directly into the eyes (for example bright ceiling lights or sunny windows). Reflected glare, such as on computer screens, sometimes causes eyestrain. This is because the contrast between the image you are viewing and its background is reduced by the reflected light, making it harder for your brain to interpret the image. As your eyes strain, facial and eye muscles tighten.
  • Contrast is the difference in brightness between what is being viewed and the immediate environment. Excessive contrast can lead to eyestrain. This may occur if a dark screen is surrounded by a bright background, such as a window or a lit wall, or if a screen shows light text on a dark background.
  • Vision problems. You may be straining to see because you need corrective spectacles or because you need to update the prescription of your current spectacles or contact lenses.

Many studies have shown that the tiny amount of radiation emitted by video display terminals, including computer and television screens, does not cause eye damage or eyestrain, even after a lifetime of exposure.

Who gets eyestrain and who is at risk?

Eyestrain occurs most often among people who do close-up work, read a great deal or spend long periods watching television or using a computer. Visual problems, such as eyestrain and irritation, are among the most frequently reported complaints from computer users.

Symptoms and signs of eyestrain

Symptoms of eyestrain may include:

  • Headaches
  • Blurred or double vision
  • Pain in the eye
  • Red, watery eyes
  • Dry eyes that feel scratchy or uncomfortable
  • Burning sensation when you close your eyes
  • Aching heaviness of the eyelids or forehead, especially around the eyebrows
  • Back aches and neck aches
  • Muscle spasms in the muscles surrounding the eyes
  • Twitch in the eyelid

How is eyestrain treated?

Having eyestrain does not mean you need to stop using your eyes, or that permanent damage will result. However, you should identify the cause of the eyestrain and correct it. This could involve:

  • Having an eye examination to see if you need spectacles and to exclude any eye disease or disorder.
  • Having your vision tested to make sure your prescription is correct if you already wear spectacles or contact lenses.
  • Assessing your work environment. A professional trained in ergonomics (the science of organising the work environment for maximum efficiency) may be helpful in arranging your workstation to reduce eyestrain.

You can also relieve eyestrain by using these practical tips.

How to relieve and prevent eyestrain

  • Ensure that any close-up work or computer screen is not too close to your eyes. As a general rule, view material from as great a distance as possible, provided it can still be easily read.
  • Take frequent vision breaks (at least every hour) to relax your eye muscles. Try closing your eyes and relaxing for one minute. Other useful exercises may include rolling or blinking your eyes, or closing them tightly for a few seconds.
  • Changing focus is another way to relieve the eye muscles. Every 15 to 30 minutes, look across the room or out of the window at an object at least 6 m away, for at least 20 seconds.
  • You can tire your eyes if you have to alternate frequently between two objects placed at different focus distances. If more than one close-up focus area is needed (when you are using printed reference material and a computer screen simultaneously), keep the viewed objects at the same distance and as close to each other as possible. This helps to reduce focusing changes.
  • Workstations and lighting should be arranged to avoid direct and reflected glare anywhere in your field of vision. Place the computer or TV screen where there is no glare from windows or lights, and keep screens clean and dust-free. Use a glare filter on the screen if lighting cannot be modified.
  • Position the top of your computer monitor or TV screen at (or slightly below) eye level, so you can look down towards it. This can help with dry eyes. More of the eye surface is covered by the eyelid when you look down, with the result that your eyes blink more and produce more lubrication.
  • Wear sunglasses that reduce glare and provide 100% protection from ultraviolet rays while you are driving or working outside, especially on bright or hazy days. Sunglasses also prevent squinting that may strain eye and facial muscles. If you're going on a long car trip, stop every few hours to rest your eyes and stretch your muscles.
  • When reading, knitting or drawing, hold your material about 30 to 40 cm away from your eyes. Ensure you have adequate soft light (a 60 to 100-watt bulb or equivalent) behind you.
  • When using a computer or similar equipment, room lighting should not be as bright as the screen. To reduce troublesome contrast, find a way to darken the area around the screen. Keep your computer monitor in proper focus.
  • While you are watching TV, the room lighting should be about 50% dimmer than the screen. Don't watch in darkness because this makes the contrast in light too great. Avoid viewing from an angle and sit at a reasonable distance from the TV (about four or five times the width of the screen). In other words, in the case of a 50-cm screen, sit about 2 to 2.5 m away. People with poorer sight may need to sit closer. Children with uncorrected short-sightedness often sit close to the screen in order to see more clearly. An ophthalmologist (eye specialist) or optometrist can diagnose this condition and prescribe corrective glasses.
  • If your eyes feel particularly dry after any visual activity, try an over-the-counter teardrop product, containing polyvinyl alcohol (a wetting agent) or methylcellulose.

When to call the doctor

Resting your eyes usually relieves eyestrain. However, if you suffer prolonged discomfort or notice a change in your vision, make an appointment for an eye examination without delay.

Previously reviewed by Dr L.C. Boezaart

Revieved by Dr Clive Novis, Ophthalmologist, (November 2010)

 
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