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PubMedDate not supplied

Computer vision syndrome: a review.

As computers become part of our everyday life, more and more people are experiencing a variety of ocular symptoms related to computer use. These include eyestrain, tired eyes, irritation, redness, blurred vision, and double vision, collectively referred to as computer vision syndrome. This article describes both the characteristics and treatment modalities that are available at this time. Computer vision syndrome symptoms may be the cause of ocular (ocular-surface abnormalities or accommodative spasms) and/or extraocular (ergonomic) etiologies. However, the major contributor to computer vision syndrome symptoms by far appears to be dry eye. The visual effects of various display characteristics such as lighting, glare, display quality, refresh rates, and radiation are also discussed. Treatment requires a multidirectional approach combining ocular therapy with adjustment of the workstation. Proper lighting, anti-glare filters, ergonomic positioning of computer monitor and regular work breaks may help improve visual comfort. Lubricating eye drops and special computer glasses help relieve ocular surface-related symptoms. More work needs to be done to specifically define the processes that cause computer vision syndrome and to develop and improve effective treatments that successfully address these causes.

Asthenopia↗

PubMed2006

Is there a twenty third amino acid in the genetic code?

The universal genetic code includes 20 common amino acids. In addition, selenocysteine (Sec) and pyrrolysine (Pyl), known as the twenty first and twenty second amino acids, are encoded by UGA and UAG, respectively, which are the codons that usually function as stop signals. The discovery of Sec and Pyl suggested that the genetic code could be further expanded by reprogramming stop codons. To search for the putative twenty third amino acid, we employed various tRNA identification programs that scanned 16 archaeal and 130 bacterial genomes for tRNAs with anticodons corresponding to the three stop signals. Our data suggest that the occurrence of additional amino acids that are widely distributed and genetically encoded is unlikely.

Amino Acids↗

PubMed2004

Accuracy of digital panoramic images displayed on monitor, glossy paper, and film for assessment of mandibular third molars.

OBJECTIVE: The aim of this study was to compare the accuracy of 3 modalities of digital panoramic radiographs-monitor-displayed images and printed copies on glossy paper and on blue transparent film-for assessment of position and morphology of mandibular third molars. STUDY DESIGN: 164 third molars were recorded with one of 2 digital panoramic systems (Digora and Orthophos Plus) and assessed by 4 observers on 3 radiographic modalities: monitor display, glossy paper, and transparent film. The assessments were compared with surgeons' findings at the time of the operation ("gold standard"). RESULTS: Overall, the observer variation was larger than the variation between methods. A detailed paired analysis revealed some differences between the modalities for some diagnostic categories, but these were few and inconsistent. CONCLUSION: Printed images from the Kodak 1200 ink-jet printer on glossy paper and blue transparent film may be as accurate as the original monitor-displayed digital panoramic images from the Digora and Orthophos Plus systems for assessment of position and morphology of mandibular third molars.

Adolescent↗

PubMed2006

The characterization of waste cathode-ray tube glass.

New re-use applications are needed to address the relatively large quantity of waste electronic products generated in the world. Cathode-ray tubes (CRTs) from computer monitors and TV sets are a large component of such waste. The three glass components of CRTs are the funnel, panel and neck, which are produced by various manufacturers and are now collected by asset-recovery centres. In this paper, we characterize waste funnel and panel glass from dismantled cathode-ray tubes with a view to assisting the development of new re-use applications. The heavy metal (lead, barium, and strontium) content of such glass represents an acute risk to the environment. Our results of the chemical composition for different kinds of waste CRT glass including black & white and color CRTs show that CRT glass from different producers have generally similar chemical compositions. In particular, the compositions of funnel and panel black & white CRT glass are similar, but are different to those of panel and funnel color CRT glass. We also measured the following specific properties of each type of CRT glass: density, glass transition temperature, and linear coefficient of thermal expansion. It was found that the coefficients of thermal expansion of CRT glass do not vary with their composition. In contrast, the measured densities and glass transition temperatures do vary with composition. On the basis of our experimental data and data found in the literature, we outline the main properties of several waste CRT glass currently in circulation. The aim of this study was to provide the data required to determine if this kind of waste could be entirely (or partially) re-used and to aid the search for promising methods of treatment.

Computer Terminals↗

PubMed2003

On the role of peripheral visual afferent information for the control of rapid video-aiming movements.

It has been shown that, even for very fast and short duration movements, seeing one's hand in peripheral vision, or a cursor representing it on a video screen, resulted in a better direction accuracy of a manual aiming movement than when the task was performed while only the target was visible. However, it is still unclear whether this was caused by on-line or off-line processes. Through a novel series of analyses, the goal of the present study was to shed some light on this issue. We replicated previous results showing that the visual information concerning one's movement, which is available between 40 degrees and 25 degrees of visual angle, is not useful to ensure direction accuracy of video-aiming movements, whereas visual afferent information available between 40 degrees and 15 degrees of visual angle improved direction accuracy over a target-only condition. In addition, endpoint variability on the direction component of the task was scaled to direction variability observed at peak movement velocity. Similar observations were made in a second experiment when the position of the cursor was translated to the left or to the right as soon as it left the starting base. Further, the data showed no evidence of on-line correction to the direction dimension of the task for the translated trials. Taken together, the results of the two experiments strongly suggest that, for fast video-aiming movements, the information concerning one's movement that is available in peripheral vision is used off-line.

Biomechanical Phenomena↗

PubMed2002

Visual protective sheet can increase blink rate while playing a hand-held video game.

PURPOSE: To evaluate the effectiveness of a protective sheet in reducing eye strain caused by unnecessary light reflection on portable liquid crystal display panels while playing Game Boy (Nintendo, Kyoto, Japan). DESIGN: Nonrandomized clinical trial. METHODS: The blink rates of 24 normal volunteers were measured under relaxed conditions while viewing a portable liquid crystal display panel and playing Game Boy with and without the protective sheet of polyethylene terephthalate with antiglare coating for a total of 10 minutes each. RESULTS: The results showed a dramatic increase (from 5.6 +/- 3 to 9.1 +/- 4.9 [P <.0001]) in blinks/minute with use of the protective sheet. CONCLUSION: The protective sheet has shown the possibility of increasing the blink rate by making the screen easier to see.

Adult↗

PubMed2001

A compatible chord code for inputting elements of Chinese characters.

A compatible chord code for inputting elements of Chinese characters (ECC) to computer was proposed. It capitalized on the graphic compatibility between ECC and chord combination of keys (CCK) on a single-handed chord keyboard with five keys. Experimental results showed that the proposed compatible chord code was better than a code that randomly mapped ECC onto CCK with respect to learning time and response time. Explicit indication of the graphic compatibility between ECC and CCK did not enhance memorizing the compatible code.

Adolescent↗

PubMed2001

An investigation of how acute muscle pain modulates performance during computer work with digitizer and puck.

The purpose was to investigate the influence of muscle pain on work performance during computer work with digitizer and puck. Muscle pain was induced by infusion of hypertonic saline in the trapezius and the extensor carpi ulnaris (ECU) muscles on two separate days. Twelve healthy subjects participated. A computer task was performed in three 6 min sessions: baseline, pain, after pain. The computer task comprised production of drawings at maximal work pace. One drawing was defined as a work cycle. Work cycle time, number of puck button clicks, and screen pixels the cursor had moved per cycle were assessed. Shoulder pain did not influence these variables. Cycle time decreased from 13.8 (SD 2.2) to 13.0 s (SD 1.9) compared to baseline (p < 0.05) during ECU muscle pain. The increased or unchanged performance suggests that acute moderate muscle pain has minor influence on performance during computer work with digitizer and puck.

Adult↗

PubMed2001

Musculoskeletal, visual and psychosocial stress in VDU operators before and after multidisciplinary ergonomic interventions. A 6 years prospective study--Part II.

A prospective epidemiological field study covering a 2 years period has earlier been published. The study has a parallel group design with two intervention groups (T and S) and one control group (C) of Visual Display Unit (VDU) operators. The present paper covers the period from 2 to 6 years of the study. After 3.5 years, the C group got the same intervention in terms of new lighting system, new workplaces and at last an optometric examination and corrections if needed. The C group reported a significant reduction in visual discomfort after interventions while the two groups (T and S) continued to report significant reduction of visual discomfort after 6 years. By supporting the forearm on the table top, the C group reported significant reduction of shoulder and neck pain while the T group reported significant reduction in shoulder and back pain after 6 years. Organizational and psychosocial factors at work and outside work did not show any significant changes during the study period.

Computer Terminals↗

PubMed2002

Computer-telephone interactive tasks: predictors of musculoskeletal disorders according to work analysis and workers' perception.

Sixty-two workers engaged in computer-telephone interactive tasks in an active telemarketing center and a telephone call center of an international bank subsidiary in São Paulo. Brazil, were assessed by means of a work analysis and a self-administered questionnaire aiming to determine the statistical relationship of ergonomic, organizational and psychosocial characteristics of their jobs with the report of symptoms in neck-shoulder and hand-wrist for more than 7 consecutive days and any time away from work during the current job due to musculoskeletal disorders (MSD). According to chi-square univariate tests and multiple logistic regression models, active telemarketing operations, duration in the job and the low level of satisfaction with the physical arrangement of the workstation emerged as the factors most related to neck-shoulder and hand-wrist MSD and MSD-induced time away from work. This study emphasizes the role of psychosocial factors and duration in the job in MSD occurrence and induced absenteeism among workers engaged in computer-telephone interactive tasks.

Adult↗

PubMed2002

Short term and long term effects of enhanced auditory feedback on typing force, EMG, and comfort while typing.

Two studies were conducted to determine the effects of enhanced auditory feedback on typing force, electromyography (EMG) and subjective discomfort. The introduction of enhanced auditory feedback caused a 10-20% reduction in 90th percentile typing force, finger flexor EMG, and finger extensor EMG. Adaptation to the enhanced auditory feedback occurred in <3 min. After 1 week of intermittent enhanced auditory feedback there were no differences in typing force or EMG while subjects were typing with or without the enhanced auditory feedback. The continued use of auditory feedback did not further reduce the levels of typing force or EMG after 1 or 2 weeks of exposure.

Adult↗

PubMed2003

The effect of an ergonomic computer device on muscle activity of the upper trapezius muscle during typing.

OBJECTIVE: Investigate whether an ergonomic computer device, characterised by an inclined working area and keyboard localisation close to the screen (the Up-Line), decreases the muscle activity of the upper trapezius muscle. METHODS: In a crossover design 19 healthy subjects and 19 patients with Whiplash Associated Disorder (WAD) typed during 10 min at the Up-Line and at a standard workstation with 15 min of rest in between. During typing surface EMG was measured of the trapezius muscle. The subjects were asked to rate sitting comfort and complaints. RESULTS: Although most subjects subjectively preferred the Up-Line, on average no significant differences were found in muscle activity between the two workstations for both patients and healthy subjects. Individually in 5 healthy subjects (25%) and in 6 patients (31%) muscle activity was lower when working at the Up-Line. CONCLUSION: Although some subjects subjectively prefer the Up-Line in sitting comfort, on average the Up-Line did not decrease the muscle activity, both in healthy subjects as in patients with WAD.

Adult↗

PubMed1997

Applying epidemiological principles to ergonomics: a checklist for incorporating sound design and interpretation of studies.

The primary purpose of this paper is to provide a checklist of scientific requirements necessary for the design of sound ergonomics studies. Ergonomics researchers will be able to use the checklist when designing a study and preparing it for publication. Practitioners can use the checklist to critically appraise study results, thereby having greater confidence when applying ergonomic recommendations to the workplace. A secondary purpose of the paper is to pilot the checklist on a sample of papers in the ergonomics literature and to assess its reliability. While there are checklists to assess the epidemiological rigour of studies, none have been adapted to address methodological issues in ergonomics. Two epidemiologists independently searched five ergonomics journals (Applied Ergonomics, Ergonomics, Human Factors, International Journal of Human-Computer Interaction and Journal of Human Ergology) for research studies on VDT use and visual function published between 1990 and 1995. Twenty-one articles were reviewed. Each paper was scored according to the checklist. Overall, the reviewers found that the articles did not consistently fulfill some of the checklist criteria. An insufficient sample size was the most serious omission. Inter-rater reliability of the checklist was excellent for 11 of 14 items on the checklist (Kappa > 0.74), good for two items (Kappa between 0.40 and 0.74) and poor for one item. As ergonomics is gaining acceptance as an integral part of occupational health and safety, individuals in this field must be cognizant of the fact that study results are being applied directly to workplace procedures and design. It is incumbent upon ergonomists to base their work on a solid research foundation. The checklist can be used as a tool to improve study designs and so ultimately has implications for improving the fit between the worker and the work environment.

Computer Terminals↗

PubMedDate not supplied

Computer mouse or Trackpoint--effects on muscular load and operator experience.

The aim of the study was to evaluate four different modes of human-computer interaction. The modes were: use of the keyboard alone as input device, use of keyboard and mouse, use of keyboard and mouse with a three-dimensional arm support, and use of a keyboard with a Trackpoint device in its centre. Ten women and 10 men volunteered to participate. Questions asked were whether working in the different modes influenced shoulder and forearm muscular load differently during word processing, and how much strain on the neck, shoulder and arms subjects perceived in the different modes. Muscular load was studied with electromyography in three shoulder muscles and three forearm muscles. The subjects also rated the different modes in one questionnaire concerning perceived strain and in one concerning preference for any of the modes tested. Intra-individual analysis for each muscle and mode showed two possible ways of decreasing the strain from computer mouse work on the shoulder muscles--either to use Trackpoint or to use the mouse combined with the movable arm support. However, both of these computer-interaction modes increased the muscular load in the hand and forearm.

Adult↗

PubMed1998

Musculoskeletal, visual and psychosocial stress in VDU operators before and after multidisciplinary ergonomic interventions.

The study has a parallel group design with two intervention groups (T and S) and one control group (C) of VDU operators. Three serial interventions were carried out in the T and S groups, first a new lighting system, then new workplaces and last an optometric examination and corrections if needed. The new lighting gave significantly increased illuminance levels, increased luminances of the room surfaces and better luminance distribution. The two intervention groups reported significant improvement of the lighting conditions, as well as of the visual conditions and significantly reduced visual discomfort and glare. Significant reduction of headache was found in one of the intervention groups. Optometric corrections reduced the visual discomfort in both the intervention groups. When looking at those given new corrections, a significant reduction was found in the T group and a clear tendency was also found in the S group. The C group reported no improvements for any of these health outcomes. The workplace intervention gave the operator the possibility to support the whole forearm and hand on the table top. Before the intervention there were no significant differences between the three groups regarding shoulder pain and static trapezius electromyographic (EMG) load. Two years after the intervention, a significant reduction of shoulder pain was reported in the T and S groups in parallel with a significant reduction in static trapezius load, while no such reduction was found in the C group. At the same time, both static trapezius load and shoulder pain were significantly lower in the T and S groups compared with the C group. Pain in the forearm and hand showed no significant changes in any of the groups during the study period. However, there seem to be a relationship between pain in the forearm and hand and the time the operator used the mouse. The C group reported significantly higher intensity of pain and used the mouse significantly more than the S group.

Back Pain↗

PubMed1998

A process for the development, specification and evaluation of VDU work tables.

Development, specification and evaluation of a work table, suitable for VDU work with a mouse, was carried out in collaboration with furniture manufacturers, employees and an employer in a Research and Development Company. Ten VDU-operators expressed their ideas for improvements at their present workstations and the company and the researchers made a preliminary version of workstation specification to the furniture manufacturers. The three different furniture manufacturers set up four test stations with prototype tables, which were evaluated by 39 subjects using comfort ratings. The results of the comfort ratings and comments from the subjects were used when the final specification for new workstations was made. Three new work tables were evaluated in the ten selected operators' ordinary environment. Evaluations were made by technical recordings of physical load during work and by preference studies. The most important results from the evaluation can be summarized as follows: the work table should make it possible to support the arms, make it possible to vary between sitting and standing posture and prevent extreme outward rotation of the shoulder. Futhermore, the study showed that it is possible to improve the furniture manufacturers' knowledge and attitudes regarding how to minimize musculoskeletal disorders and to improve the study persons' working technique.

Adult↗

PubMed1998

Work content and satisfaction before and after a reorganisation of data entry work.

The aim of the study was to analyse the psychosocial and physical effects of a reorganisation of data entry work at a data processing unit with 153 employees. The reorganisation was planned to redistribute the repetitive work and improve health and satisfaction as well as efficiency. Methods used were questionnaires and, for a sub-group of 22 participants, interviews, diaries and video recordings. During the one-and-a-half-year study period the data processing unit was closed down and the employees transferred to units with more varied tasks. The reorganisation gave opportunities to improve working conditions. The results of this study show that important improvements were achieved. The majority of the 22 participants got less data entry work and the changes permitted a better work-load distribution. However, the work content after the reorganisation still did not provide satisfactory mental variation for most of the subjects, and the changes did not seem to affect health complaints.

Adult↗

PubMed1999

Static three-dimensional modelling of prolonged seated posture.

Prolonged seating can cause musculo-skeletal problems in the long term if poor postures are adopted. A three dimensional static model of the body to calculate the intervertebral disc compression at the fifth lumbar disc was built. SAMMIE, a computer aided ergonomics package was used for modelling a computer operator workstation and determination of joint centre locations and joint angles in a seated posture. Experimentation was also performed to determine the body-mass distribution on the seat used. No significant difference between male and female body-mass distribution was found. The static model found postures with the seat pan and backrest reclined to predict the lowest disc compression. Postures in which the operator was bent forwards gave the highest disc loadings.

Biomechanical Phenomena↗