By Dr Mohan Rajan and Dr Sujatha Mohan
Computers have become indispensable in the workplace. The professionals spend increasing amounts of time sitting at their computer work- stations and they take less and less breaks. At the same time productivity has increased and workers are exposed to working at high speed and to tight deadlines.
Computer Vision Syndrome – CVS is defined as that complex of eye and vision problems related to near work, which is experienced during or related to computer use.
The Computer population in India is 20 Million plus and 80% of them (16 Million) have discomfort due to CVS. The prevalence of eye symptoms among computer users ranges from 25-93% as reported by various investigators. The combination of fixed and constrained body postures, work overload and unsuitable workstations can lead to health problems. The most common complaints among computer users are aches and pains in the shoulder, forearm, wrist, hand, back and neck and eye strain.
RSI [Repetitive Strain Injury ] is a blanket term that is used to describe many different types of work-related disorders and injuries to the upper limbs as a result of muscular overload. This overload is usually caused by repetitive movements and/or overuse of specific muscle groups (categorised as static load), especially if the joints adopt extreme positions. RSI is not a new disease and also affects people who do not work at a keyboard.
Clearly, a large percentage of computer workers experience eye symptoms and subsequently seek eye care. Computer Vision Syndrome is that set of eye and vision symptoms related to near work which is experienced during or related to computer use.
These symptoms can include-Headaches, Neck aches, Eyestrain, Back aches, Blurred vision, Light sensitivity, Dry or irritated eyes, Double vision.
These symptoms are often a result of a combination of three factors:
1) Workplace conditions
2) Working habits
3) Visual condition
Please note that you are regarded as a keyboard operator if you spend more than two hours per twenty-four hour period working at a computer. The chair you sit on- the weight on your lower back is one and a half to two times bigger than when you stand. A good chair must accommodate your body sizes and must be adjustable.Height of the
Height of the seat- When your feet rest comfortably on the floor, a90 degree angle between upper and lower legs is desirable. In this position, your upper legs are virtually horizontal.
Depth of the seat- The clearance between the front edge of the seat and the back of your knee must fit a clenched fist.
Backrest-The backrest must support the area from the upper ridge of the pelvis to the shoulder blades. The curve in the backrest must support the hollow in your lower back. An adjustable tilt is desirable.
Pic courtesy: chicagotribune
What are the primary factors that determine discomfort for computer users?
*Nature of the task
*Length of time spent at the computer
*Reduced rate of blinking
Lack of coordination between the design of the workstation and the design of the glasses or contact lenses used for the task. The average rate of blinking is 12 to 15 times per minute. This is frequently reduced during intensive tasks leading to visual fatigue and dry eyes. Therefore, reading from a screen reduces blinking, which in turn, leads to discomfort.
Here are some examples of situations that usually increase user discomfort:
Intense tasks such as games
Tasks with few breaks from the screen
Tasks which require constant looking from copy to screen such as data entry
Detailed tasks such as desk top publishing or Computer Assisted Design (CAD)
Eye level placement of screens causes eyes to be wide open causing faster drying.
Eye level screens are too high for most bifocal wearers unless they have specially designed glasses for this task.
Many glasses exacerbate the restriction of movement which is a consequence of most computer tasks causing neck, shoulder, and arm problems
Lighting- Ideal lighting conditions should be between 180- 460 lux levels.
Effects of Good Lighting
Good lighting design can significantly help reduce discomfort due to glare. Light leaving the fixture can be directed so that it goes straight down and not into the eyes of the room occupants. This is most commonly accomplished with the louvres in the luminaire or fixture. An even better solution is indirect lighting in which the light is bounced off the ceiling – resulting in a large low luminance source of light for the room.
Wear a visor. This is actually a very efficient way to eliminate the brightness of overhead fixtures. A person can wear a visor for a day or two as a test to determine the extent to which the light problem alleviates discomfort at the end of the day.
How to minimise eye discomfort?
1.Place the screen further away since eye strain tends to increase as tasks are closer. 20-28 inches from your eyes.
2.Design the workstation to place the screen at least a few inches below eye level and eliminate reflections from the screen.
3. Do not have the screen excessively bright. Keep your monitor screen clean.
4.Have moderate background ambient illumination with supplemental task lighting for hard copy documents. Ideally, the illumination from the screen should closely match the light reflected from the document.
5.Use a copy holder to place documents so they are at the same distance from the users eyes as the monitor.
6.Place hard copies in a plane parallel to the plane of the user’s head to minimize reflections, maximize legibility of print, and keep the whole document the same distance from the user’s eyes.
7. Have properly designed lenses for the task
8. Use supplementary eye lubricants as indicated
9. Minimize glare on your computer by turning your monitor away from the window, reducing strong overhead light, balancing overhead and window light with a desk lamp, using an anti-glare screen
10.Give your eyes a break. Frequently look away from your monitor for a few seconds.
See your eye care professional regularly to update your prescription.
Working at the computer is not harmful to the eyes. So you do not need to have your eyes tested on a regular basis. However, your employer must give you the opportunity to have your eyes examined if you are a first-time keyboard operator or if you have eye problems.
Pic courtesy: TheOdysseyOnline