Computer vision syndrome: Strained sight

First it was only the television; then came computers; later we welcomed laptops. And now we have netbooks, tablets, smartphones, book readers and more. Very soon we’ll have Google Glass, a wearable computer with an optical head-mounted display being developed by Google.

Screens—of all types and sizes—have become an integral part of our lives. More and more people are spending an increasing number of their waking hours staring at one. The benefits of technology aside, such exposure to screens comes with its own issues. One of the major ill-effects that screens are responsible for is a condition known as computer vision syndrome [CVS]. Some of the symptoms of this condition are:

• Need to strain the eyes to see properly
• Headaches
• Burning sensation in the eyes
• Tiredness of vision
• Blurred vision
• Double vision
• Dry eyes
• Loss of focus
• Pain in the neck and shoulder areas

Many of these symptoms are temporary, however in some individuals they may continue if corrective measures are not taken.

What causes CVS

The way our eyes and brain respond to the characters on a monitor is not the same as they do to the characters on paper. The eyes need to work harder to view the characters on a screen as the letters are not always as clearly defined with tight levels of contrast as in printed literature. The presence of glare, reflections and smudges on the screen add to the difficulty. Given these challenges, the eyes drift to a reduced level of focussing and the brain attempts to strain the eye muscles to recover a high resolution of the screen display. This continuous refocussing creates muscle fatigue and eye strain.

Here are some other causes of CVS

• Uncorrected or under corrected refractive errors
• Wearing improper glasses that are not designed for computers
• Abnormal postures resulting in muscle spasms or pain in the neck, shoulder or back
• Viewing angles—the viewing distances and angles used for screens are quite different from those used for reading paper-based literature or traditional writing. This places an additional pressure on the eyes.
• Relative lack of blinking when viewing computer screens—this prevents the much required nano breaks for the eye muscles. This condition occurs because the visual demands of the task exceed the visual abilities of the individual to comfortably perform them.

Who is at risk?

Those who spend two or more continuous hours at a computer every day are at a higher risk of CVS than others.

How is it diagnosed?

The impact of CVS is assessed through comprehensive eye tests covering:

Patient history—to determine symptoms and any general health problems, understand the medications taken, or other environmental factors.

Refraction—for the lens prescription needed to compensate for nearsightedness, farsightedness, astigmatism or presbyopia.

Eye muscle co-ordination testing—to look for problems that keep your eyes from focussing effectively or make it difficult to use both eyes together. This testing may be done with or without the use of eye drops to determine the eyes’ response under normal seeing conditions.

Detailed slit lamp evaluation—for other eye disorders.

Prevention

This involves taking steps to control lighting and glare on the computer screen, establishing proper working distances and posture for computer viewing, and ensuring that even minor vision problems are addressed and corrected immediately.

Suggestions by the American Optometric Association to prevent or treat CVS

• Some individuals benefit from glasses prescribed specifically for computer use. Lenses prescribed to meet the visual demands of computer viewing also help. Special lens designs, lens powers or lens tints and coatings help to maximise visual abilities and comfort
• People with issues like decreased convergence or accommodation will need vision therapy. Also known as visual training, vision therapy is a structured programme of visual activities prescribed to improve visual abilities. It trains the eyes and brain to work together more effectively. These eye exercises help correct deficiencies in eye movement, eye focussing and eye teaming and reinforce the eye-brain connection. Treatment may include office-based as well as home training procedures
• Optimally, the computer screen should be 15 to 20 degrees below eye level [about 4 or 5 inches] as measured from the centre of the screen and 20 to 28 inches from the eyes
• Reference materials should be located above the keyboard and below the monitor. If this is not possible, a document holder can be used beside the monitor. The goal is to position the documents so you do not need to move your head to look from the document to the screen
• Position the computer screen to avoid glare, particularly from overhead lighting or windows. Use blinds or drapes on windows and replace the light bulbs in desk lamps with bulbs of lower wattage
• If there is no way to minimise glare from light sources, consider using a screen anti-glare filter, which decreases the amount of light reflected from the screen
• The brightness and contrast of your screens should be the same as your work environment
• Chairs should be comfortably padded and conform to the body. Chair height should be adjusted so that your feet rest flat on the floor. If your chair has arms, they should be adjusted to provide arm support while you are typing. Your wrists shouldn’t rest on the keyboard when typing.

To prevent eyestrain, try to rest your eyes when using the computer for long periods. Rest your eyes for 15 minutes after two hours of continuous computer use. Also, for every 20 minutes of computer viewing, look into the distance 20 metres away for 20 seconds to allow your eyes a chance to refocus and relax [20-20-20 rule].

Make an effort to blink frequently. Blinking keeps the front surface of your eye moist and also use lubricating eye drops.

This was first published in the September 2013 issue of Complete Wellbeing.