There are a lot of researches about computer’s influence on humans health. Special attention is paid to such problems as visual impairments, overload of certain parts of locomotor apparatus, and different psychological problems. Results of these researches show that the first complaints about health problems may occur as early as a few months after a person has begun to work on the computer. Serious illnesses, including occupational diseases, are usually detected after five or more years.
When working with the computer, the most part of working day is spent sitting. In such position the body reduces the energy consumption, the blood flow slows down, the back muscles relax, and the curvature of lower back reduces, forming so called flat back. As a result, the pressure on the intervertebral discs increases, causing back pain. In order to hold the body in a sitting position, musculature must be kept in tense position (the so called static load).
Muscles can withstand such static load only if it is small. In the case of static load, muscles, tendons, nerves, and joints are not sufficiently supplied with blood, causing metabolic disorders, pain, fatigue, tension, and other complaints (RSI – repetitive strain injuries). Static load affects arm muscles as well, for example, work with computer mouse causes enhanced fatigue, sharp and burning pain, and numbness in hands. These complaints are common in cases when computer users are working with different graphic programs and are using the mouse for more than 10 hours a week.
Work with the keyboard is connected with active movements in joints of wrists and fingers. The long term working and making of repeated and frequent movements can cause thickening of muscle tendons in the area of wrist joints. This thickening compresses nearby nerves and blood vessels, causing so called Carpal tunnel syndrome. The main complaints of this syndrome are weakness in the hands and wrists, numbness of fingers, and decrease of finger sensitivity. Pain and tingling appear mainly at night and disappear after a short period of moving.
One of the most typical compaints of computer users is visual discomfort, which is felt as irritation and tearing. Eyes quickly get tired, hurt, and often are red. Sometimes visual acuity can change as well. These complaints usually occur at the end of the working day. Normally people blink eyes up to 22 times per minute, but during working with the computer – about 3 times less frequently. As a result, eyeballs are not sufficiently moistened. This condition is known as dry eye syndrome. In the case of dry eye syndrome people complain about eye tearing, which is reflex response to irritation. Eye tearing is more characteristic for young people, but in this case tears are deficient. If dry eye syndrome is left untreated, defences against other eye diseases also lower, for example, against allergic or infectious inflammations.
Human vision physiologically changes with age. For humans after 40 years of age elasticity of eye lenses decreases, therefore they cannot clearly see objects that are placed closer than 30 – 40 cm. This is presbyopia. Visual load from the work with the computer encourages the early development of presbyopia. Vision is negatively affected by the other conditions where people have to greatly strain their eyes in order to see the image on the monitor. Some of these conditions can be prevented by people themselves, for example, by wiping the dust from the monitor, adjusting the monitor so that it does not glare, etc.