CVS

Computer Vision Syndrome (CVS)

Recent studies have shown that about 85 per cent of computer users suffer from computer vision syndrome

Computer Vision Syndrome (CVS) is a complex eye and vision-related problem associated with computer use. Recent studies have shown that about 85 per cent of computer users suffer from this problem, possibly making it the silent epidemic of the 21st century.

Hence it is important to know a few essential things about CVS.

Symptoms

The primary symptoms are eyestrain, blurred vision, dry and irritated eyes, tired eyes, and headaches. Neck and backaches can also be related to the way we use our eyes at the computer.

Causes

There are several reasons, but the most important reason is that the blink rate (16 / min) is reduced to about 1/3 the normal rate. This leads to irritation, dryness, excessive tearing, burning, itching and redness.

Contact lens wearers also often experience problems with their contact lenses. In response, reflex tearing sometimes occurs and floods the eyes with tears.

Precautions

Use artificial tears to rewet and lubricate your eyes. Lower the computer screen so that the centre of the screen is four to eight inches below your eyes. If seated in a draft or near an air vent, try to eliminate the flow of air past your eyes.

Low humidity or fumes aggravate a dry eye condition, so fix these if possible. Blink whenever you begin to sense eye discomfort; close eyelids and roll eyes frequently.

While working on computers, use glasses with anti-reflection coating. These are advised for those wearing lens as well. For those with presbyopia (glasses for reading after 40 years), the best solution is a lens that is specifically designed for this purpose.

Because the eyes lead the body, the body will assume whatever position is required to enable your eyes to see comfortably. The most optimum viewing distance is considered to be 20-28 inches.

Care for eyes

Care of a person with CVS often requires an expanded case history, testing of the eyes or vision, or treatment since it involves taking into consideration many aspects.

Perfect computer display

Flat panel (LCD) are better than cathode ray tube (CRT) displays since they do not flicker and the contrast is typically higher. Optimal contrast and visibility are attained with black characters on a white background.

The size of the text should be three times the size of the smallest text you can read. Adjust refresh rate (flicker) as high as possible, preferably 85 hertz or higher. For colour monitors, smaller dot pitches (less than 0.28 mm) are desirable.

Adjust the screen contrast so that the characters are clear. Reflections from your computer screen reduce the contrast and make it difficult to see your work. If possible, remove the offending source of light - turn off the source, draw blinds and :

Know the best lighting

Bright lights or other bright objects in your peripheral vision are uncomfortable and can contribute to eye and musculoskeletal symptoms.

* Try the following measures.
* Turn off the light that is bothering you.
* If window light is causing discomfort, draw blinds.
*
Alter your workstation position so that bright overhead lights or bright windows are not in your field of vision. If a desk lamp is causing discomfort, try turning if off and determine whether you can still adequately see your work.
* Use a shield or partition to block bright lights.

Blurring of vision

Intermittent blurring is caused by an inability of the accommodative mechanism to maintain a steady focus on near objects.

This occurs when, after extended near work, the muscles remain fixed or somewhat locked in the near contracted position, effectively making the eye myopic, taking a few seconds to focus on objects. Sometimes this can last for several hours.

This can even affect driving and can be treated with spectacles and exercises. Eyelids flutter or twitch because the muscle surrounding the eye is fatigued. Take periodic breaks, eliminate glares and consider an eye examination.

There is no way that screen and the keyboard can be optimally located with laptops and notebooks and extended work is not recommended on these.

The author is cornea and refractive surgeon, Narayana Netralaya, Bangalore.
Computer Vision Syndrome (CVS)