What factors influence the eye

The widespread introduction of computers in all spheres of human activity has caused a wave of messages about their impact on human health. A number of the functional disorders of the nervous system, until the seizures. There were cardiovascular disorders , dermatitis skin. There were reports of abuse of pregnancy in VDT users . However , ultimately failed to confirm connection described disorders (except dermatitis ) to work for a computer screen . The only firmly established fact are disorders of vision in VDT users .They appear at first increased visual fatigue , and then a number of functional disorders, the combined term " eye-strain ." They include discomfort in the eye , and temporary loss of vision at near and far . Thus real eye diseases (cataract , glaucoma , etc.) do not occur. Not only is a clear possibility of occurrence or progression of myopia in the background of long-term work with the computer. In studying the effect of the display on the operator's body in the first place there is the question of the effects of electromagnetic radiation. Displays made ​​by electron-beam tubes , are a potential source of soft x-ray , ultraviolet , infrared, visible , radio , over and low-frequency electromagnetic radiation.If they meet the State Standard of the Russian Federation , then these radiation does not have any harmful effects on humans . For different types of computers magnitude soft X-ray radiation , even at a distance of 5-10 cm from the screen does not exceed the established norms. Levels of ultraviolet and infrared radiation below natural background or conform to them and may not cause harmful interference . In the workplace, users have the displays low-intensity electromagnetic radiation that does not exceed the allowable values ​​of the electric and magnetic fields in the frequency range of 60 kHz - 300 MHz. The maximum level of electric field intensity is registered at the rear of the display panel and somewhat less - 10 cm from the screen and the display housing .In studying the effect of electromagnetic radiation on the body of the operator , researchers found no adverse effects of this radiation on the eye. The only condition that can be associated with the electrostatic field display - it dermatitis skin. Can be regarded as established that the main influence on the operator has no electromagnetic radiation , and hand- intensive work with the monitor. The literature contains contradictory information about the impact of the display on sight . Some authors , for a long time watching the state of the users do not find significant functional changes , while others point to a direct correlation between the intensity of visual work and the state of view. Moreover, this effect is largely dependent on the age of the user on its refractive indices of the physiological state of , and the intensity and duration of the monitor and work area.In a study of Bulgarian authors of a large number of users VDT ( 5703 people). Noted the following symptoms : redness of the eyes ( 48.44 %) , pruritus ( 41.16 %) , pain ( 9.17 %) , " goose bumps " in the eyes (36 , 11%) , discomfort (5.6%) , a sense of gravity ( 3.94 %) , general discomfort ( 10.48 %) , headache (9.55 % ), fatigue ( 3.23 %) , darkening in the eyes ( 2.59 % ), dizziness ( 2.22 %) , double vision (0.16 %). In this case, the objective changes were noted in the visual system : decreased visual acuity ( in 34.2 % of cases) , accommodation disturbances ( in 44.73 % of cases) , convergence ( in 52.02 % of cases) , binocular vision ( 49.42 % cases) stereovision ( in 46.8 % of cases) .In the United States received a circulation term " commuter eye syndrome " , the frequency of its rapidly growing : in 1992, complaining of eye turned to the optometrist about 10,000 people VDT , and in 1996 - already 15 000 . As described above, the cause of these phenomena - not the physical radiation of a computer monitor , and visual features of this device. The display is different from the paper so that it is in their characteristics : self-luminous , not reflected , has a much lower contrast , is not continuous , but consists of discrete points - pixels , flickering ( flitting ) , that is, those points with some frequency turn on and off the lower the frequency of the flicker , the less accurate the installation of accommodation.