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See Well - Work Well
Human eyes function less strenuously when looking at a distance. Working on a computer requires use of your eyes at a closer range, usually intensely, for long periods of time. This alone can strain your eyes and may cause vision problems or aggravate existing conditions. Typical computer work involves shifting the focus of the eyes from document to keyboard to screen, on average at least once every second. This unnatural situation is often the cause of eye-strain and operator stress.
Eye-strain
Eye-strain is a term used to describe a wide range of symptoms including tiredness, irritation and soreness of the eyes, screwing up the eyes, photophobia (discomfort in bright light) and headaches. Eye-strain is often the cause of headaches and relief can often be obtained by means of prescription lenses, contact lenses or vision therapy.Due to the intense demands made on the visual system, people using computers are more prone to suffer from above symptoms. These can be brought about by various factors, including refractive errors and ocular muscle imbalances, incorrect sitting and equipment design limitations, unsuitable lighting and surroundings and psychological factors. Fortunately most computer-related vision problems can be easily alleviated through proper workstation planning, work habits, and most importantly, professional eye care.
Common symptoms of computer terminal eye-strain:
- Headaches
- Tired, sore eyes
- Eye irritation
- Blurred vision
- Slow refocusing when looking from copy or screen to distant objects
- Frequently losing place when moving eyes to screen and vice versa
- Difficulty in seeing clearly at distance after prolonged use of computer terminal
- Changes in colour perception
- Present lens prescription failing to relieve symptoms.
Other symptoms from which computer operators may suffer:
- Neck or shoulder tension or pain
- Back pain
- Excessive physical fatigue
- Increase in irritability when using computer
- Pain in arms, wrist and shoulders
- Increased nervousness
- Lowered visual efficiency and increased frequency of errors.
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Computer workstation suggestions
Many vision and stress problems can be alleviated by making changes in the work environment. Follow the following suggestions for optimum computer positioning:- Make sure the terminal is not placed in such a way that the operator sees only the screen or the wall behind the screen.
- Look well beyond the screen out into space every few minutes.
- Computer screens should be slightly below eye level (about 20 degrees). Copy or documents being read should be at the same level as the screen.
- The screen should be positioned 500-600 mm from the operator’s eyes.
- Locate the keyboard in a position so that the wrist and lower arm are parallel to the floor.
- Chairs should provide proper back and leg support and be height adjustable.
- Adjust the chair height so that feet are flat on the floor or rest on a foot support with thighs parallel to the floor.
Office equipment technology is constantly being improved and where possible, advantage should be taken of new products which make for more comfortable operation.
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Lighting - a vital factor
One of the main causes of complaints from computer operators is glare. This can occur as a result of reflections from the surfaces of the computer screen and from high contrast between the text, screen and surroundings. The ideal is to have even, comfortable illumination.Consider the following:
- Lighting in the work environment where computers are used should be as indirect as possible.
- Fluorescent ceiling lights should be fitted with diffusers. If at all possible, lighting should be beamed upwards to diffuse against the ceiling.
- Computer workstations should be provided with adjustable shaded copy lamps that can be moved by the operator to avoid screen glare.
- Match as closely as possible the brightness of surroundings with that of the computer screen for optimum comfort and efficiency. However, the contrast between the characters on the screen and the screen background should be high.
- Minimise reflected glare in computer screens by having them positioned away from windows and other sources of bright light. Use window shades, vertical blinds and curtains to block out excessive sunlight.
- Adjust the computer contrast and brightness to achieve the most comfortable viewing level. These adjustments may need to be made at different times during the day if the work environment is influenced by altering levels of daylight.
- Anti-glare screens are available.
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Maintenance of computer terminals
Regular maintenance of computers is essential to avoid, for example, a reduction in brightness, contrast and legibility. Older computers in particular, tend to require regular focus and alignment resetting to ensure visual sharpness and avoid flickering and movement of the display. Diminished screen image clarity will lead to significant eye-strain and operator stress.For the best operator performance and efficiency:
- Look up and away from the computer every few minutes.
- Take frequent short breaks.
- Have a comprehensive optometric examination annually. Make sure your optometrist knows about your current computer use.
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Industrial situations | Recommended protective eyewear | Ramification of eye injuries | Factors conducive to pro-ficient performance
The standard of workers’ vision affects their work activity and productivity. without adequate vision, workers cannot work well.
Good vision is vital for any worker, whether working in an office, handling heavy equipment or working with electrical components, fittings or chemicals. Faulty or poor vision can cause eye-strain, fatigue, headaches and nervousness and lead to simple mistakes or serious accidents.
There are very few acitvities that can be conducted safely, efficiently and effectively without good vision. Poor vision can even be mistaken for poor workmanship.
Vision changes slowly over the years. The natural loss of the focusing ability of the eyes, called presbyopia, causes near vision problems for the worker from the age of 40 onwards. At this stage, workers may need spectacles to see well.
With presbyopia, the nearest point of clear focus moves progressively further away, and at the same time the eyes usually become less sensitive to differences in colour and contrast, and more sensitive to glare.
This makes it more difficult to focus on fine print or read from low-contrast backgrounds. Tasks such as working on computers or inspecting large diagrams will present problems, as they require frequent refocusing of the eyes.
To maintain optimum visual efficiency, workers should undergo a routine vision examination once every year, and their eyes need to be protected in the work situation at all times.
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Industrial situations
Workers in potentially hazardous environments should always wear protective eyewear to ensure the safety of their eyes.Many eye accidents could be avoided by wearing correct eye protection. The type of safety eyewear required depends on the work tasks and the worker’s visual environment. These are some of the products available:
Impact-resistant spectacles These spectacles have no prescription and provide limited frontal protection against flying particles.
Safety prescription lenses These are made of hardened glass, plastic resin or polycarbonate and are at least 3 mm thick. They provide frontal protection against flying objects. The frames for these lenses are specially designed to hold the lenses securely under heavy impact. Side shields which can be attached to the temples of the frames are available for additional protection.
Goggles These offer frontal and side protection from flying particles, dust or liquid splashes. They can be worn alone or over safety prescription spectacles. Special non-misting gauze goggles should be used in hot environments such as mines, foundries and furnace areas.
Face shields These provide splash protection when working with chemicals, while also protecting to a limited degree against flying particles and dust. When working with highly toxic chemicals, whether in gas, liquid or solid form (acids or powders), goggles should be worn under the face shield, as not all face shields are resistant to chemicals. There are three types -standard, curved (these go right around the ears) and chemical (protect right under the chin).
Welding helmets These contain special filter lenses for protection against welding rays, sparks and flying particles. The filter would need to be appropriate for the task performed.
Tinted lenses These lenses provide various levels of protection from infrared and ultraviolet rays as well as the discomfort and glare from strong sunlight.
Protective eye equipment should be kept in peak condition. The straps, frames and other parts should fit the wearer snugly and correctly. Excessively scratched or chipped safety lenses lose their impact resistance and should be replaced.
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Recommended protective eyewear for common industrial hazards
- Machining, light grinding and chipping - safety spectacles with side shields.
- Heavy grinding and chipping -flexible goggles which fit closely to the head.
- Laboratory work and chemical handling - face shields.
- Electric arc welding - welding helmets or goggles with special tinted lenses. Anybody working near the welding operation should also wear eye protection.
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Ramification of eye injuries
- Loss of man-hours
- Loss of income to the worker
- Loss of production
- Possible loss of employment
- Medical costs
- Damaged machinery
- Legal implications.
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Factors that can be conducive to pro-ficient performance of visual tasks
- Work areas should be well lit
- Minimal reflections off working surfaces
- Minimal glare or reflections from outdoors
- Workers should be given regular breaks from repetitive tasks
- Chairs should be adjustable for personal comfort.
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