Visual Display Terminal Work Research Articles

Effects of visual display terminal works on cervical movement pattern in patients with neck pain.

[Purpose] This study examined changes in the onset of neck movement in young adults with and without mild neck pain (MNP) during visual display terminal (VDT) work. [Subjects] Ten control subjects and 10 subjects with MNP who were VDT workers were recruited. The upper (UC) and lower cervical (LC) spine angles in the sagittal plane were collected using an ultrasound-based motion analysis system during VDT work for 5 min. [Results] The MNP group had faster movement initiation in the UC and LC compared with the control group during VDT work. [Conclusion] These findings suggest that young adults with MNP should be cautious when performing VDT work while sitting.

Changes in cervical range of motion, flexion-relaxation ratio and pain with visual display terminal work

The static posture in visual display terminal (VDT) workers results in increased forward neck flexion and increased static muscle tension in the neck and shoulder regions. However, few studies have objectively quantified the change in head posture induced shoulder pain during VDT work. This study elucidated changes in pressure pain in the upper trapezius muscles, cervical ROM, and the cervical flexion--relaxation ratio after continuous long-term VDT work. Twelve young VDT workers were recruited. The pressure pain of the upper trapezius muscles, active CROM, and cervical flexion--relaxation ratio were measured in all subjects once before and once after VDT work. The pressure pain threshold of the right upper trapezius muscle was 6.9 ± 1.6 lb before VDT work and 6.1 ± 1.0 lb after VDT work, revealing a significant increase with VDT work. The cervical extension, left and right lateral flexion, and left rotation measurers decreased significantly with VDT work. We postulate that even short-term VDT work has the potential to cause problems. It is necessary to develop a CROM self-measuring device and to monitor patients' musculoskeletal changes frequently.

A Study of Musculoskeletal Disorders among Visual Display Terminal Workers

This study investigated the effectiveness of workstation ergonomic intervention in reducing musculoskeletal disorders (MSD) in Visual Display Terminal (VDT) workers. The study was carried out at one of a Multinational Company in Petaling Jaya, Selangor. Sixty Heavy VDT workers were selected randomly as case study respondents. Questionnaires were given to 60 respondents to investigate their awareness in ergonomic intervention, job-related factors that contributing to musculoskeletal disorders, as well as MSD severity and symptoms among them. Then, 30 workers who are heavy VDT users were selected to receive the education and ergonomics interventions, whereas another 30 receive the education and ergonomic intervention, whereas another 30 workers were assigned as a control group. The two groups were then crossedover after sixth week, and follow-up questionnaire s we given to all of them once again. The results for both questionnaires, before and after the ergonomics intervention, were then analyzed for this case study. The interventions include ergonomics leaflets, ergonomic posters, online ergonomic education and ergonomic working posture guidance. The outcomes suggested that a participation in an ergonomics program, even though in a short duration and minimally disruptive to the normal workplace routine, can still contribute to a rapid effect on improving work posture. Although improper posture is associated to be the main risk factor for work-related musculoskeletal disorders, multigroup and long-term randomized trial are required to establish the effectiveness or workstation ergonomic intervention in reducing musculoskeletal disorders in VDT workers. In conclusion, there is significant evidence that individualized ergonomic interventions may contribute to improve work-related posture and reduce MSD injuries for VDT workers.

Analysis of risk factors for dry eye syndrome in visual display terminal workers

To analyze the risk factors for dry eye syndrome in visual display terminal (VDT) workers and to provide a scientific basis for protecting the eye health of VDT workers. Questionnaire survey, Schirmer I test, tear break-up time test, and workshop microenvironment evaluation were performed in 185 VDT workers. Multivariate logistic regression analysis was performed to determine the risk factors for dry eye syndrome in VDT workers after adjustment for confounding factors. In the logistic regression model, the regression coefficients of daily mean time of exposure to screen, daily mean time of watching TV, parallel screen-eye angle, upward screen-eye angle, eye-screen distance of less than 20 cm, irregular breaks during screen-exposed work, age, and female gender on the results of Schirmer I test were 0.153, 0.548, 0.400, 0.796, 0.234, 0.516, 0.559, and -0.685, respectively; the regression coefficients of daily mean time of exposure to screen, parallel screen-eye angle, upward screen-eye angle, age, working years, and female gender on tear break-up time were 0.021, 0.625, 2.652, 0.749, 0.403, and 1.481, respectively. Daily mean time of exposure to screen, daily mean time of watching TV, parallel screen-eye angle, upward screen-eye angle, eye-screen distance of less than 20 cm, irregular breaks during screen-exposed work, age, and working years are risk factors for dry eye syndrome in VDT workers.

Comparison of the Lumbar Flexion Angle and EMG Activity in Trunk Muscles in Individuals with and without Limited Hip Flexion Range of Motion during Visual Display Terminal Work with Cross-Legged Sitting

[Purpose] The purpose of this study was to compare the lumbar flexion angle and electromyography (EMG) measurements of trunk muscle activity in individuals with and without limited hip flexion range of motion (ROM) during visual display terminal (VDT) work with cross-legged sitting. [Subjects] The 15 participants included a control group with sufficient hip flexion ROM (n = 7) and an experimental group with limited hip flexion ROM (n = 8). [Methods] All subjects performed VDT work with cross-legged sitting. The lumbar flexion angle was measured using a three-dimensional motion capture system, and the trunk muscle activity was recorded using a surface EMG system during VDT work with cross-legged sitting. The differences in trunk flexion angle and trunk muscle activity between the two groups were analyzed using independent t-tests. [Results] The lumbar flexion angle was significantly greater in the experimental group than the control group, although trunk muscle activity did not differ between the two groups. [Conclusion] These findings suggest that limited hip flexion leads to greater lumbar flexion during cross-legged sitting.

教示内容の違いがVDT作業中の頭部・胸郭・骨盤の角度に与える影響

本研究の目的は，VDT作業による腰痛予防の方法を考案するための基礎研究として，作業中に与える言語的・視覚的教示が作業中の脊柱が屈曲した姿勢であるSlumped Sitting姿勢を改善する効果があるかを検討することである．脊柱に整形外科疾患の既往のない健常男性9名を対象とし，教示なし条件と言語的教示条件，視覚的教示条件の3条件で同一被検者に30分間のパソコンを使用した文字入力作業を行わせた．文字入力作業中の姿勢は頭頚部，胸郭そして骨盤の連続的な二次元計測による角度と即時的な三次元計測による角度に着目して分析した．基準姿勢の角度から作業中の姿勢の角度との差を算出し，2つの教示条件の効果を検討した．結果として教示なし条件と比較して視覚教示条件で連続的な二次元計測システムによる頭部傾斜角度と即時的な三次元計測システムによる骨盤に対する胸郭の角度は有意に減少した．このことからVDT作業中のSlumped Sitting姿勢予防の手段の1つとして視覚的教示が有効であることが示唆された．

Cross-Sectional Study on the Relationship between Visual Display Terminal Work and Symptoms in the Eyes and the Musculoskeletal System among Teachers and Clerks of a University and Its Affiliated Schools

Cross-Sectional Study on the Relationship between Visual Display Terminal Work and Symptoms in the Eyes and the Musculoskeletal System among Teachers and Clerks of a University and Its Affiliated Schools

Efficacy of a novel moist cool air device in office workers with dry eye disease

To evaluate the efficacy and safety of new moist cool air device (MCAD) for ocular symptoms, tear film stability and ocular surface status in office workers with dry eye disease (DED). In this prospective single-centre clinical trial, 40 eyes of 20 patients with DED were recruited and randomly divided into two groups (group with MCAD exposure and group without MCAD). All subjects are visual display terminals (VDTs) workers spending at least 4 h/day in front of VDTs. Patients using MCAD underwent moist air applications for 4 h/day for a total of five working weekdays during VDT works at their offices. The other group of patients performed their VDT work without moist cool air device exposure. The change in symptoms of ocular surface (OS) dryness, fatigue and discomfort was evaluated using visual analogue scale (VAS) scores. Changes in visual function, tear functions and ocular surface status were evaluated using best-corrected visual acuity (BCVA), the functional visual acuity (FVA) test, blink rate, BUT measurements, strip meniscometry (SM), tear evaporation rate, fluorescein staining and rose bengal staining scores. Tear film lipid layer interferometry was also performed to assess the status of the lipid layer over the tear film. In addition, adverse events were recorded. In group with MCAD, symptoms of OS dryness during VDTs work, and FVA and BUT were significantly improved. SM and tear evaporation rate were significantly improved. There were no statistically significant differences on lipid layer stability and corneal staining scores in both groups. Blink rate was significantly increased in group without MCAD. No adverse events were reported during this trial. Moist cool air device use provided symptomatic relief of ocular dryness and improvement on tear stability in office workers with DED. This new device seems to be a safe and promising alternative in the treatment of DED.

Effects of a Large Area Glare Source in Cognitive Efficiency and Effectiveness in Visual Display Terminal Work

Glare is a common visual stressor of office work and in today's offices the prevalence of information and communication technologies adds additional mental demands. The aim of this study was to explore the role of light as a cognitive stressor in visual display terminal (VDT) work. We used a large area light source in a 2 × 2 × 2 full factorial experimental design. We assessed cognitive efficiency using the RTLX method and cognitive effectiveness using the RST method in different lighting scenarios. The main effects analysis showed lower working memory capacity for high luminance and large source, with statistically significant lower cognitive performance in prosaccade conditions. No statistically significant relationship was found between cognitive efficiency and the experimental factors.

Changes in the Center of Force in the Gluteal Region and Pelvic Tilt Angle after Continuous Visual Display Terminal Work

Changes in the Center of Force in the Gluteal Region and Pelvic Tilt Angle after Continuous Visual Display Terminal Work

Changes in Craniocervical and Trunk Flexion Angles and Gluteal Pressure during VDT Work with Continuous Cross‐legged Sitting

This study investigated changes in craniocervical and trunk flexion angles and gluteal pressure on both sides during visual display terminal (VDT) work with continuous cross-legged sitting. The gluteal pressures of ten VDT workers, who were recruited from laboratories, were measured using a Teckscan system and videotaped using a single video camera to capture the craniocervical and trunk flexion angles during VDT work at 30 s, 10, 20 and 30 min. The craniocervical angle was significantly increased at 10 and 20 min compared with the initial angle (p<0.05). The trunk flexion angle was significantly decreased at 30 s, 10, 20 and 30 min (p<0.05). The gluteal pressure of the crossed-leg side significantly increased at 30 s, 10 and 20 min (p<0.05). The gluteal pressure of the uncrossed-leg side significantly decreased at 30 s (p<0.05). We found that cross-legged sitting during VDT work may exert disadvantageous postural effects resulting from craniocervical and trunk flexion angles and gluteal pressure. Therefore, this posture could not be recommended during long-term VDT work.

The Impact of Contact Lens Wear and Visual Display Terminal Work on Ocular Surface and Tear Functions in Office Workers

To evaluate the effect of contact lens (CL) wear and visual display terminal (VDT) work on the ocular surface and tear functions. Prospective case-control study. Sixty-nine CL wearers (45 women and 24 men; mean age, 35.2 ± 7.3 years), and 102 age- and sex-matched non-CL wearers were enrolled in the study (66 women and 36 men; mean age, 36.7 ± 7.3 years). Ocular surface and tear function tests, including vital stainings (fluorescein and rose bengal), Schirmer test, tear meniscus height measurement, and tear film break-up time were performed. The subjective symptoms of dry eyes were evaluated using a dry eye symptom questionnaire. The participants were divided into 4 subgroups according to the total time of VDT work in 1 day (VDT work time in 1 day ≥ 4 hours or < 4 hours) and presence of CL wear. Main outcome measures included ocular surface vital staining scores, Schirmer test results, tear film break-up time, tear meniscus height measurement, and symptom questionnaire score. CL users and long-term VDT workers showed significantly worse tear meniscus height values than non-CL users and short-term VDT workers (P < .001). The mean visual symptom scores in CL wearers and long-term VDT workers were significantly higher than the other groups (P < .001). Office workers who wore CLs and spent more than 4 hours engaged in VDT work had a lower tear meniscus volume with significant dry eye and visual symptoms triggered by environmental factors.

The immediate effects of 830-nm low-level laser therapy on the myofascial trigger point of the upper trapezius muscle in visual display terminal workers: A randomized, double-blind, clinical trial

The aim of our study was to evaluate the immediate effects of an 830-nm Aluminium gallium arsenide (GaAlAs) laser, by examining the changes, in pressure-pain threshold (PPT) and tenderness at 3 kg of the myofascial trigger point (MTrP) of the upper trapezius muscle in visual display terminal (VDT) workers in comparison with placebo treatment. Thirty VDT workers (13 males, 17 females) with complaints of upper trapezius muscle were recruited. All participants were given either active GaAlAs laser (830 ㎚ wavelength, 450 ㎽, 9 J at point) or placebo GaAlAs laser, according to the double-blinded and placebo-controlled trial. Both active and placebo low-level laser therapy (LLLT) treatments showed no significant effect on PPT and tenderness at 3 kg. These results suggest that a higher dosage may be necessary to produce immediate effects when applying LLLT to the MTrP of relatively large muscles such as the upper trapezius muscle.

Effects of a Visual Feedback Device for Hip Adduction on Trunk Muscles and Sitting Posture in Visual Display Terminal Workers

This study was designed to identify the effects of a visual feedback device for hip adduction on trunk muscles and sitting posture when working at a visual display terminal. The forward head and trunk flexion angles of 20 workers were analyzed using a motion analysis system, and the activities of the lower trapezius, external abdominal oblique, internal abdominal oblique, and L5 paraspinal muscles were analyzed using a electromyography system. The statistical significance of differences between using and not using a visual feedback device was assessed by paired t tests. Using the visual feedback device during Visual Display Terminal work significantly decreased the forward head and trunk flexion angles, and significantly increased the activities of the external abdominal oblique, internal abdominal oblique, and L5 paraspinal muscles. The authors suggest that the visual feedback device for hip adduction promotes the adoption of standard spine and pelvic postures, which might be effective in preventing poor sitting postures.

Gender differences in insomnia and the role of paid work and family responsibilities

A higher prevalence of insomnia in females has been consistently demonstrated across countries and cultures. The aim of this study was to clarify whether gender differences in insomnia could be explained by gender differences in paid work and family responsibilities. Participants were employees at two local governments in Hokkaido, Japan, who underwent annual health checkups from April 2003 to March 2004. All data were obtained via self-administered questionnaires. Insomnia was evaluated by the Athens Insomnia Scale. For work and family characteristics, occupation, working hours, days off, shift work, visual display terminal (VDT) work, occupational stress, marital status, hours spent on household tasks, childcare, and caregiving were chosen. Data from 7,451 participants (5,951 men and 1,500 women) were analyzed. Logistic regression analysis examined how much paid work and family responsibilities explained gender differences in insomnia. The prevalence of insomnia in female subjects (31.0%) was significantly larger than in males (23.2%), but the gender difference disappeared after adjustment for paid work and family responsibilities. The results of stratified analyses revealed that significant gender differences were found only among workers with comparatively favorable work and family conditions, such as non-shift work, less than 6h/day of VDT work, exposure to low levels of occupational stress, household tasks for less than 1h/day, and not living with persons who needed care and support. These results suggest that gender differences in insomnia are explained, in the main, by gender differences in work and family characteristics.

(-)-Bornyl acetate induces autonomic relaxation and reduces arousal level after visual display terminal work without any influences of task performance in low-dose condition

(-)-Bornyl acetate is the main volatile constituent in numerous conifer oils and has a camphoraceous, pine-needle-like odor. It is frequently used as the conifer needle composition in soap, bath products, room sprays, and pharmaceutical products. However, the psychophysiological effects of (-)-bornyl acetate remained unclear. We investigated the effects of breathing air mixed with (-)-bornyl acetate at different doses (low-dose and high-dose conditions) on the individuals during and after VDT (visual display terminal) work using a visual discrimination task. The amounts of (-)-bornyl acetate through our odorant delivery system for 40 min were 279.4 µg in the low-dose and 716.3 µg in the high-dose (-)-bornyl acetate condition. (-)-Bornyl acetate induced changes of autonomic nervous system for relaxation and reduced arousal level after VDT work without any influences of task performance in low-dose condition, but not in high-dose condition.

Effectual Points of View in Occupational Health Management for Persons with Cerebral Palsy —Interventional Case Approach in VDT Work—

In our previous study, we elicited effectual points of view (POV) in occupational health management for visual display terminals (VDT) operators with disabilities. In order to validate the POV, two VDT operators with cerebral palsy newly-participated in our case study. Problems were ascertained, and in order to attempt to reduce the workload and improve operability, we performed intervention using ergonomic measures. Evaluations were conducted through observations of the equipment used and posture, as well as measurements of sitting pressure distribution and surface electromyogram. For Case 1 (a 33 yr-old male), a trunk support was introduced inside the armrest of his chair to maintain the trunk in a comfortable position. For Case 2 (a 21 yr-old female), in order to improve her unstable sitting position, we changed her chair and adjusted it to an appropriate desk height. For both cases, we confirmed improvements in posture, sitting pressure distribution, myoelectric potential or operability. We were able to confirm that "maintaining of a comfortable trunk" and "alleviation of excessive bending, extension, and curvature of the spinal column and joints" obtained from the previous study as POV in health management are also effective in the present interventional cases.

Relationship between Active Cervical Range of Motion and Flexion–Relaxation Ratio in Asymptomatic Computer Workers

A high prevalence and incidence of neck and shoulder pain is present in the working population, especially sedentary workers. Recent findings have indicated that the flexion-relaxation (FR) ratio in the cervical erector spinae (CES) muscles might be a significant criteria of neuromuscular impairment and function. Additionally, the active cervical range of motion (ROM) is frequently used for discriminating between individuals with pain and those who are asymptomatic. The purpose of the present study was to examine the relationship between the active cervical ROM and the FR ratio in a sample of regular visual display terminal (VDT) workers. In total, 20 asymptomatic male VDT workers were recruited. Active cervical ROM was measured by a cervical ROM (CROM) instrument. Surface electromyography (EMG) was used to collect myoelectrical signals from the CES muscles, and the FR ratio was calculated for statistical analysis. Pearson correlation coefficients were used to quantify the linear relationship between the active cervical ROM and the FR ratio. The values obtained for the FR ratio in the right CES muscles correlated significantly with the active cervical ROM measured in flexion (r=0.73, p<0.01), left lateral flexion (r=0.64, p<0.01), and left rotation (r=0.60, p<0.01). Flexion (r=0.74, p<0.01) and right lateral flexion (r=0.61, p<0.01) positively correlated with the left FR ratio. Extension and right rotation showed either a very weak or no correlation with the mean value of the right and left FR ratio. Our findings suggested that the cervical FR ratio had a positive correlation with cervical movements, and that changes of the activation patterns in CES demonstrated as cervical FR ratio are associated with reduction of the cervical range of motion including flexion and lateral flexion. In addition, muscular dysfunction of the CES could occur in regular computer workers prior to occurrence of pain; this means that the FR ratio could be used to evaluate the potential risk of neck discomfort in computer workers.

Lacrimal Hypofunction as a New Mechanism of Dry Eye in Visual Display Terminal Users

BackgroundDry eye has shown a marked increase due to visual display terminal (VDT) use. It remains unclear whether reduced blinking while focusing can have a direct deleterious impact on the lacrimal gland function. To address this issue that potentially affects the life quality, we conducted a large-scale epidemiological study of VDT users and an animal study.Methodology/Principal FindingsCross sectional survey carried out in Japan. A total of 1025 office workers who use VDT were enrolled. The association between VDT work duration and changes in tear film status, precorneal tear stability, lipid layer status and tear secretion were analyzed. For the animal model study, the rat VDT user model, placing rats onto a balance swing in combination with exposure to an evaporative environment was used to analyze lacrimal gland function. There was no positive relationship between VDT working duration and change in tear film stability and lipid layer status. The odds ratio for decrease in Schirmer score, index of tear secretion, were significantly increased with VDT working year (P = 0.012) and time (P = 0.005). The rat VDT user model, showed chronic reduction of tear secretion and was accompanied by an impairment of the lacrimal gland function and morphology. This dysfunction was recovered when rats were moved to resting conditions without the swing.Conclusions/SignificanceThese data suggest that lacrimal gland hypofunction is associated with VDT use and may be a critical mechanism for VDT-associated dry eye. We believe this to be the first mechanistic link to the pathogenesis of dry eye in office workers.

Interactive Model of Subsidiary Behaviors, Work Performance and Autonomic Nerve Activity during Visual Display Terminal Work

The aims of the study were to investigate the systematic classification of subsidiary behaviors during visual display terminal (VDT) work and discuss the interpretation of these behaviors through an interactive model of subsidiary behaviors, work performance and autonomic nerve activity. Twelve university students were instructed to perform continuous 120-min English transcription tasks in a sedentary posture. Data on subsidiary behaviors, work performance (mean keystroke and mean error rates), and autonomic nervous system balance (log-transformed low frequency (LF) / high frequency (HF) ratio) were recorded every 5 min during VDT work. The subsidiary behaviors were categorized into 3 qualitatively independent factors: distractive behaviors against monotony (DBM), sleepiness-related behaviors (SRB), and habitual behaviors (HB). A cross-correlation analysis indicated that an increase of DBM, which is considered as a sign of workers' attempt to escape from monotonous task operations, was related to a decline in performance. A decrease in the LF/HF ratio was followed by SRB after 5 min passed (r=-0.57, p<0.05), eventually leading to a restriction of the deterioration in performance. An increase of DBM was predictive of an increase in errors (r=0.54, p<0.05), and a significant negative correlation (r=-0.46, p<0.05) between HB and autonomic nerve activity at 10 min after the appearance of HB was observed. It emerged from the results that the factor structure of subsidiary behaviors consists of 3 mutually independent factors. The interactive model suggests that subsidiary behaviors are possibly precursory signs of errors and changes in autonomic nervous system balance.