Eye Strain

6 Key excerpts on "Eye Strain"

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  eBook - ePub

  Encyclopedia of Microcomputers

  Volume 6 - Electronic Dictionaries in Machine Translation to Evaluation of Software: Microsoft Word Version 4.0

  • Allen Kent, James G. Williams, Allen Kent, James G. Williams(Authors)
  • 2019(Publication Date)
  • CRC Press

    (Publisher)

  Health and Safety at Work. The study found that 70% of respondents experienced eyestrain and 34% reported blurred vision. It is important in this context to distinguish between eye damage and dysfunction and eyestrain. Medical evidence suggests that screen-based work does not damage eyesight nor aggravate existing eye problems. There is evidence, though to support the suggestion that it can lead to short-term visual discomfort or visual fatigue, that is Eye Strain. Such a conclusion is hardly surprising when we see the type of work which some people are asked to do on a computer and the environmental conditions within which the machines are operated.

  Eyestrain and visual fatigue are largely preventable if attention is paid to the visual environment within which the computer user works. The most common source of eyestrain comes from glare; glare from the screen itself, the lighting in the room, both artificial and daylight, and from the room surfaces. Reducing or eliminating glare via the proper positioning of the VDU unit and the provision of appropriate lighting can go a long way toward reducing visual discomfort. Traditional office lighting was designed for desk work, and is generally too bright for reading characters on a reflecting vertical surface, which computer-based work requires.

  The quality, as well as the quantity, of lighting is also important; certain types of lighting are more restful than others. Further factors influencing the extent to which visual fatigue is experienced by the computer user are the screen display, its color, contrast, and stability; the length of time that people work on the machine without a break; and the type of work which they do. The eye like any other muscle will tire if held in the same position for long periods of time.

  It should also be remembered that eyestrain is not a new phenomenon brought about by computer-based work. Many other industrial and clerical tasks make similar visual demands upon individuals. People who wear glasses can experience particular difficulties when using computers, especially those whose glasses are designed for a narrow range of reading distance or who wear multifocal lens glasses. Such glasses are not designed to cope with work involving varying visual distances such as VDU work. Such problems can be easily overcome by modifications to their prescription, and a consultation with an optician before starting screen-based work can sort this out.

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  Human Factors in Lighting

  • Peter Robert Boyce(Author)
  • 2014(Publication Date)
  • CRC Press

    (Publisher)

  533 Light and Health The symptoms of eyestrain are irritation of the eyes, evident as inflammation of the eyes and lids; breakdown of vision, evident as blurring or double vision; and referred effects, usually in the form of headaches, indigestion, giddiness, etc� Anyone who experiences eyestrain frequently can hardly be said to be enjoying the best of health� The symptoms of eyestrain are likely to appear whenever the visual system is faced with a difficult visual task, under- or overstimulation, distraction or percep-tual confusion (see Section 5�3)� These conditions can be brought about either by poor lighting, the inherent features of the task and its surroundings, the limitations of the individual’s visual system or some combination of these factors� There are two mechanisms by which eyestrain can be caused, one physiological and one perceptual� The physiological itself can take two forms, dryness of the surface of the eye and muscular strain in the oculomotor system, that is, in the muscle system that controls the accommodation and convergence of the eyes (Sheedy et al�, 2003; Sheedy, 2007)� The perceptual is the stress that is felt when the visual system has difficulty in achieving its primary aim, to make sense of the world around us� Conditions that call for prolonged near viewing or that require the oculomotor sys-tem to hold a fixed position for a long time or to make frequent movements of the same type are likely to produce eyestrain through muscular exhaustion� Conditions that make it difficult to see what needs to be seen or that distract attention from what needs to be seen are likely to produce eyestrain through stress� Lighting conditions that have been shown to lead to eyestrain are inadequate illuminance for the task (Simonson and Brozek, 1948), excessive luminance ratios between dif-ferent elements of a task (Wibom and Carlsson, 1987), glare

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  Visual Ergonomics Handbook

  • Jeffrey Anshel(Author)
  • 2005(Publication Date)
  • CRC Press

    (Publisher)

  Thus, I believe that it should be addressed as an independent issue that must be resolved. The causes for the inefficiencies and the visual symptoms are a combina-tion of individual visual problems and poor office ergonomics. Poor office ergonomics can be further divided into poor workplace conditions and improper work habits. The above-mentioned survey also concluded that two thirds of the complaints were related to vision problems while one third were due to environmental factors. Many people have marginal vision dis-orders that do not cause symptoms when performing less demanding visual tasks. However, it has also been shown that computer users also have a higher incidence of complaints than noncomputer users in the same envi-ronment (Udo et al., 1991). Let’s review these symptoms and see if we can determine how they arise and how they may be addressed, both visually and environmentally. Eyestrain The eye care professions maintain a vague definition of eyestrain. One tends to think of a strain as what would happen to a muscle if it were overworked. In fact, it is rarely a strained muscle that causes the complaint of eyestrain. The medical term for eyestrain is asthenopia (AS-then-OH-pee-ah), which itself is a rather vague term. The visual science dictionary defines asthenopia as the subjective complaint of uncomfortable, painful, and irritable vision. It then gives 24 different types of asthenopia based on various causes. Because of its subjectivity, however, it can have a myriad of meanings to any number of people. Asthenopia can be caused from some underlying condi-tions such as focusing spasm, different vision in each eye, astigmatism, hyperopia, myopia, excess light, voluntary focusing, eye coordination diffi-culties, and more. Computer Vision Syndrome 25 When confronted with the complaint of eyestrain, it would be prudent to have a complete eye examination performed to determine the exact source of the complaint.

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  Occupational Ergonomics

  Theory and Applications, Second Edition

  • Amit Bhattacharya, James D. McGlothlin(Authors)
  • 2012(Publication Date)
  • CRC Press

    (Publisher)

  Constantly focusing on nearby objects can fatigue both the involuntary and the volun-tary eye muscles. Looking back and forth between two nearby objects that are different distances from the eyes requires refocusing and can also result in muscle fatigue. This often happens when a document is much closer or farther from the eyes than the display screen. Dry eyes are a frequent complaint of computer users. Blinking is one way to keep eyes moist. Several studies have shown that humans blink at significantly lower rates when viewing display screens (Acosta et al., 1990; Yaginuma et al., 1990; Patel et al., 1991; Tsubota and Nakamori, 1993; Nakaiski and Yamada, 1999; Doughty, 2001; Schlote et al., 2003). Monitor placement also affects the percentage of eyeball exposed to ambient air. When the monitor is lower, the eyelid can cover more of the eyeball and thus reduce the surface area from which evaporation can occur (Anshel, 1998). Some visual complaints from computer users may also be associated, at least in part, with underlying psychological stress (Mocci et al., 2001). 15.3.6 Psychosocial Stress Psychosocial stress is a significant factor in the development of MSDs, including low back pain, as well as in the length of time away from work once an MSD has been recog-nized (Hult, 1954; Lawrence, 1955; Maeda et al., 1980; Smith et al., 1981; McPhee, 1982; Oxenburgh et al., 1985; Green and Briggs, 1989; Waersted et al., 1991; Moon and Sauter, 1996). Stress also influences behavior such as the amount of force used during keying, reporting of medical problems, the tendency to maintain a rigid posture, and the amount of sick time taken (Scalet, 1987). Stress in computer users is multifactorial, and may be as much related to the total job and organizational structure as to computer use itself.

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  Office Ergonomics

  Ease and Efficiency at Work, Second Edition

  • Anne D. Kroemer, Karl H.E. Kroemer(Authors)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  V ISION M YTHS …D EBUNKED * Myth 1: Working in dim or glaring light, reading fine print, wearing glasses with the wrong prescription, or staring at a computer screen will damage your eyes. Truth : Subjecting your eyes to any of those conditions over time can cause eye-strain, since the eye muscles struggle to maintain a clear or unwavering focus. In addition, prolonged staring can dry the front of the eye somewhat, because it reduces blinking, which helps lubricate the cornea. But fatigue and minor dryness, no matter how uncomfortable, will not permanently harm your vision. Of course, it makes sense to minimize discomfort and eyestrain by using the fol-lowing techniques: • “Lighten up.” Age tends to cloud the lens of the eye and shrink the pupil, sharply increasing the need for luminance. So if reading strains your * Adapted from Kroemer et al. (2001). (a) (b) (c) FIGURE 8.3 Lamps for (a) direct, (b) indirect, and (c) diffuse lighting. (From Morgan, C.T. et al., Human Engineering Guide to Equipment Design , McGraw-Hill, New York, 1963.) 171 Seeing and Lighting eyes, consider installing brighter lights or at least moving the reading lamp closer to the page. If you are using a handheld reading device, adjust the lighting to fit you best. • Cut the glare. Position the reading lamp so that light shines from over your shoulder, but make sure it does not reflect into your eyes from the computer monitor. Avoid reading or doing computer work near an unshaded window. And wear sunglasses if you are reading outside. • Stop and blink. When you are working at the computer or reading, pause frequently—say, every 15 minutes—to close your eyes, or gaze away from the screen or page, and blink repeatedly. Every hour or so, get up and take a longer break. • Find and maintain the right distance. Keep your eyes at the same distance from the screen as you would from a book.

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  Designing EEG Experiments for Studying the Brain

  Design Code and Example Datasets

  • Aamir Saeed Malik, Hafeez Ullah Amin(Authors)
  • 2017(Publication Date)
  • Academic Press

    (Publisher)

  20 In the learning process, if the learners feel visual strain and/or heavy head due to watching the S3D content, their focus and concentration will be lost. Thus, it will cause distraction to the attentional resources that are necessary for perceiving new knowledge.

  Visual fatigue and discomfort are not only issues with S3D but also occur with extensive use of computer screens or any visual display, such as TV. It has been investigated that the excessive use of display screens may cause Eye Strain, headache, visual discomfort, fatigue, and other negative effects.

  21 ,22

  The reason for these symptoms with normal visual display is the screen low refresh rate. If the refresh rate is too low, it will cause screen flickering. Thus the flashing of light may induce negative effects, such as photosensitive seizures.23 It has been reported that an individual may experience motion sickness in front of a large visual display,24 which may be due to rapid eye movements.

  In case of S3D, the symptoms of visual discomfort and fatigue are studied using subjective and/or physiological measures.

  2 ,10 ,13 ,25 –27

  It is one of the most frequent complaints of S3D viewers and considered an important dimension of the quality of experience of S3D. The reason for this widely studied factor is obvious as it concerns the health and safety of the viewers.2 Visual discomfort is the perception of the degree of annoyance during performing a visual task and can be measured as suggested by Li et al.2 , to ask the viewers to report his/her experience. However, visual discomfort may disappear quickly if the participant is distracted or closes his/her eyes. In addition, visual fatigue is differentiated by Lambooij27

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