Video Display Unit Research Articles

Video Display Unit Exposure and Risk of Musculoskeletal Symptoms During Covid-19 Pandemic

Video Display Unit Exposure and Risk of Musculoskeletal Symptoms During Covid-19 Pandemic

Ocular Problems among Video Display Terminal Users in a Software Company of Sector V, Kolkata

Background: Video Display Unit use and Information Technology creates a host of problems like Ocular Problems and Work Related Musculo Skeletal Problems. Many experience visual symptoms including eyestrain, headaches, ocular discomfort, dry eye, diplopia and blurred vision either at near or when looking into the distance after prolonged computer use. Very few and sporadic studies have been done in this part of the world especially in India, to address the issue in all its scope. Aim & Objective: To find out the proportion of different ocular problems among the study population and to find out the association of their ocular problems with the socio-demographic, work related and ergonomic factors. Materials and methods: It was an institution based, cross sectional, analytical epidemiological study and was conducted over one-year period. The study population comprised of persons working with Video Display Terminals. A predesigned, semi-structured instrument for elaborating the socio-economic, lifestyle related and a few job-related health behaviors were used. Combination of few instruments to elicit different morbidities like and many ergonomic checklists to evaluate office workspace were also used. Results: Of the total 79.1 % had any kind of ocular problems currently, with around 65% of them reporting to be having problem constantly in the last 12 months. Headache (63.6%) seemed to be the most important problem, followed by Eye fatigue (52.4%). Repetition of work and poor ergonomic practices turned out to be the statistically significant factors. Increased Years of working and female sex were also found to be important factors. Screen Character was found to be the most important risk factor of eye problems. Conclusion: A simple model was proposed where interaction of Individual factors and factors related to workstation was identified as the main culprit, which exaggerated by the repetition of work.

Prevalence of work related musculoskeletal disorders in Italian workers: is there an underestimation of the related occupational risk factors?

BackgroundWork-related musculoskeletal disorders (WMSDs) represent an important socio-economic burden. The current risk assessment and management involved in the ethiopathogenesis of WMSDs is based on observational tools and checklists, which have some limitations in terms of accuracy and reliability. The aim of this study was to assess WMSD prevalence and identify possible correlations with several socio-demographic and work-related variables in a large cohort representative of Italian workers in order to improve our understanding of the WMSD phenomenon.MethodsThis study includes data from INSuLa, a cross-sectional nationally representative survey of health and safety at work, developed by the Italian Workers’ Compensation Authority. A total of 8000 Italian workers were included. Multivariate logistic regression analyses were performed to evaluate the association of independent variables, such as workers’ perceptions of exposure to biomechanical/ergonomic and video display unit (VDU) risks (Risk Perceived) and the actual risk exposure (Risk Detected) on Back, Lower and Upper limb pain. Socio-demographic, occupational and other health-related variables were included to investigate possible association with musculoskeletal disorders.ResultsWorkers perceiving a significant exposure to biomechanical/ergonomic and VDU risks but not included in a health surveillance program for them (Risk Perceived/No Risk Detected) have had significantly higher odds of reporting musculoskeletal disorders. Regarding the biomechanical/ergonomic risk these workers are in the 19–24 age range (39.9%), transportation, warehousing/information and communication sectors (38.9%) and are employed in companies with more than 250 workers (35.8%). Regarding VDU risk, workers are in the 45–54 age range (24.5%), professional, financial and business services (38.0%) and come from companies with more than 250 employees (25.6%).ConclusionsWithin the occupational safety and health management systems an appropriate assessment of occupational risk factors correlated to musculoskeletal disorders (mainly biomechanical/ergonomic and VDU) and the correct definition of their exposure levels is essential to adequately prevent the onset of WMSDs. In this regard, our findings provide useful information to design novel approaches, aimed at improving our understanding of emerging risks, identifying gaps in current risk assessment strategies and enhancing workplace interventions are mandatory to improve the occupational risk assessment and management process and therefore implement the subsequent health surveillance systems.

INCREASING BLINK RATES: REDUCING DRIED EYE SYMPTOMS WITH EYE REST-BREAK APPLICATION

Long working hours with video display unit without appropriate breaks could drain the eyes. This study intends to investigate the efficiency of eye rest-break application to reduce dried eye symptoms by increasing blink rates. Blink rates and dried eye symptoms score among laboratory workers before and after the implementation of eye rest-break application were compared. The numbers of blink rates were recorded using a webcam for 5 minutes without the subjects aware when the recording starts or ends. Then, the Ocular Surface Disease Index (OSDI) was used to measure the dried eye symptoms. For eyes rest-break, EyeLeo© application was used. It is computer application that gives reminders to video display unit (VDU) users to take short breaks for their eyes. Six laboratory workers who are constantly working with VDU were selected as subjects. Data was analysed using Wilcoxon Signed-Rank Test, to test the comparison between variables before and after intervention by reporting its median (inter quartile range, IQR). The findings showed that the median after intervention (39.5, 10) is significantly higher (p-value = 0.028) than the median before intervention (7.3, 3). As for dried eye symptoms, median for Ocular Surface Disease Index after intervention (27.9, 8.9) is significantly lower (p-value = 0.027) than the median before intervention (36.5, 9.4). As a conclusion, application such as EyeLeo© eye rest-break is a potential intervention and may be used to increase blink rates and reducing dried eye symptoms among visual display unit workers.

Relation between psychosomatic disturbances and job stress in video display unit operators.

Some psychosomatic disturbances have been related to protracted video display unit (VDU) use at work, and they may be associated with job stress. This study aimed at assessing the association between psychosomatic disturbances with job-related and subjective stress in 990 VDU. Job stress was evaluated by Karasek's Questionnaire, psychological job demands and job decision latitude scores were calculated. Workers were assigned to four categories: high-strain job, low-strain job, active job, and passive job. Subjective perception of stress was evaluated with the Rapid Stress Assessment Scale. None of the psychosomatic disturbances investigated were associated with higher psychological job demands scores, whereas many of them were significantly related to lower job decision latitude scores and high-strain jobs. All psychosomatic disturbances were significantly associated with personal stress. Logistic regression confirms the protective role of job decision latitude on headache, fatigue, intestinal gas, disturbed sleep and the significant role of subjective stress on all psychosomatic disturbances studied. Whereas subjective stress is harmful, job decision latitude is a protective factor for several psychosomatic disturbances reported by VDU operators. Improvement in the job decision latitude might be a preventive specific measure in work planning to reduce possible stress-related disorders.

Symptomatic accommodative and binocular dysfunctions from the use of flat-panel displays.

To determine the presence of symptomatic accommodative and non-strabismic binocular dysfunctions (ANSBD) in a non-presbyopic population of video display unit (VDU) users with flat-panel displays. One hundred and one VDU users, aged between 20 to 34y, initially participated in the study. This study excluded contact-lens wearers and subjects who had undergone refractive surgery or had any systemic or ocular disease. First, subjects were asked about the type and nature of eye symptoms they experienced during VDU use. Then, a thorough eye examination excluded those subjects with a significant uncorrected refractive error or other problem, such as ocular motility disorders, vertical deviation, strabismus and eye diseases. Finally, the remaining participants underwent an exhaustive assessment of their accommodative and binocular vision status. Eighty-nine VDU users (46 females and 43 males) were included in this study. They used flat-panel displays for an average of 5±1.9h a day. Twenty subjects presented ANSBD (22.5%). Convergence excess was the most frequent non-strabismic binocular dysfunction (9 subjects), followed by fusional vergence dysfunction (3 subjects) and convergence insufficiency (2 subjects). Within the accommodative dysfunctions, accommodative excess was the most common (4 subjects), followed by accommodative insufficiency (2 subjects). Moderate to severe eye symptoms were found in 13 subjects with ANSBD. Significant eye symptoms in VDU users with accommodative and/or non-strabismic binocular dysfunctions often occur and should not be underestimated; therefore, an appropriate evaluation of accommodative and binocular vision status is more important for this population.

Group-based exercise at workplace: short-term effects of neck and shoulder resistance training in video display unit workers with work-related chronic neck pain-a pilot randomized trial.

Effectiveness of exercise therapy in video display unit (VDU) workers with work-related chronic neck pain (W-RCNP) is unclear. The aim of the study was to assess the efficacy of group-based neck-shoulder resistance exercises on symptoms and muscular function in VDU workers with W-RCNP. Thirty-five employees with CNP were randomly assigned to neck-shoulder resistance exercise (NSRE) group or to conventional stretching and postural exercise (SPE) group. Participants trained 45min, twice a week for 7weeks. Primary outcomes were pain intensity (0-10 numeric rating scale, NRS) and pain-related disability (Vernon Neck Disability Index, NDI). Secondary outcomes were cervical active range of motion (AROM), endurance of neck flexors, strength of shoulder abductors, and health-related quality of life (SF-36). Post-treatment, pain and disability decreased 2.5 and 5 points in NSRE (p=0.001) and 5 and 8 points in SPE (p=0.002), with no significant differences between groups. AROM improved significantly in both groups; between-group differences were not significant. Neck flexors endurance and shoulder abductors strength improved by 59.6 and 34.2% (p=0.001) in the NSRE group and by 27.6% (p=0.009) and 2.3% (p=0.002) in the SPE group; between-group differences were significant (p=0.016 and p<0.001, respectively). SF-36 score remained unchanged. NSRE and SPE are feasible and equally effective in reducing pain and pain-related disability as group exercises in W-RCNP. NSRE may provide some advantage in improving strength and endurance in neck muscles. Further, larger studies should confirm these findings and assess whether a better muscle function confers long-term clinical advantages.

Visual and ocular effects from the use of flat-panel displays.

To evaluate the prevalence of eye symptoms in a non-presbyopic population of video display unit (VDU) users with flat-panel displays. One hundred and sixteen VDU users with flat-panel display from an urban population participated in the study; their ages ranging from 20 to 34y. There were 60 females and 56 males. An eye examination to rule out the presence of significant uncorrected refractive errors, general binocular dysfunctions and eye conditions was carried out. In order to determine and quantify the type and nature of eye symptoms, participants were asked to answer written questionnaire and the results were grouped by gender, age and number of hours a day spent using a VDU. Seventy-two percent of participants reported eye symptoms related to VDU use. Eye symptoms from moderate-to-severe were found in 23% of participants. The main symptom was moderate-to-severe tired eyes (14%); followed by sensitivity to bright lights (12%), blurred vision at far distances (10%), eyestrain or dry eye or irritated or burning eyes (9%), difficulty in refocusing from one distance to another or headache (8%) and blurred vision at near or intermediate distances (<4%). Eye symptoms were greater among females (P=0.005) and increased with VDU use, markedly above 6h spent using a VDU in a typical day (P=0.01). Significant eye symptoms relate to VDU use often occur and should not be underestimated. The increasing use of electronic devices with flat-panel display should prompt users to take appropriate measures to prevent or to relieve the eye symptoms arising from their use.

Effect of Different Types of Rest-Break Interventions on Neck and Shoulder Muscle Activity, Perceived Discomfort and Productivity in Symptomatic VDU Operators: A Randomized Controlled Trial

Objective. This study evaluated the effect of different types of activities during rest-break interventions on neck and shoulder muscle activity, muscle discomfort and productivity among symptomatic video display unit (VDU) operators performing prolonged computer terminal work. Study design and setting. Randomized controlled trial was used. Thirty symptomatic VDU operators were randomly assigned to 2 active break groups (stretching and dynamic movement) and a reference group. The subjects performed the same typing task for 60 min and received 3-min breaks after each 20 min of work. Root mean square and median frequency were calculated for neck and shoulder muscle activity. Muscle discomfort was measured with Borg’s CR-10 scale. Productivity was measured by counting words. Results. There were no significant differences between the types of activities during breaks on neck and shoulder muscle activity, muscle discomfort or productivity. However, there was a significant difference in the level of muscle discomfort over time. Conclusions. Three types of activity during breaks showed a favourable effect on neck and shoulder muscle activity and productivity, and a positive effect on muscle discomfort in symptomatic VDU operators.

Ergonomic Comparison of a Sit-Stand Workstation With a Traditional Workstation in Visual Display Unit Work

Purpose: To compare ergonomics of an electrically adjustable sit-stand workstation with a traditional workstation in video display unit (VDU) work. Methods: Twelve female workers (aged 27-53 years) participated in this experimental study. Electromyography, wrist postures, subjective assessments, and productivity were used to make the ergonomic comparison. Results: The muscle activity of the right trapezius (p=0.01) and left wrist extensors (p=0.02), extension of the right (p=0.05) and left (p=0.002) wrist, and perceived strain of the arms (p=0.05) were lower and productivity was better (p=0.02) when the workers used a low-sitting, high-sitting, or standing posture at the sit-stand workstation than when using a low-sitting posture at the traditional workstation. In the whole, the subjects were more satisfied (p=0.05) with the sit-stand workstation than with the traditional workstation. Conclusions: Working both in sitting and standing postures was more productive and caused lower strain of the workers' upper limbs than work only in a sitting posture. The electrically adjustable sit-stand workstation offers the possibility to reduce the sedentary behavior and inactivity in VDU work.

Method for determining the best frequency band for eavesdropping the display image of a PC

The display image of the video display unit (VDU) can be reconstructed by receiving and analyzing the unexpected electromagnetic noise emanated from a personal computer system. This fact is one of the information leakage threats in information security. Therefore, in order to choose the best frequency range for receiving the electromagnetic compromising emanations form a PC display effectively and quickly, a method based on the correlation power analysis (CPA) and the common equipments is proposed. Firstly, the frequency spectrum of 10 MHz to 1 GHz is measured about 10 times respectively when the PC is displaying the white-black vertical strips image and black image. The frequency range which contains the display information can be obtained through the CPA. And then, the special image signal is searched around the dot frequency and harmonics. If the special signal disappears when displaying the total black image, it can be judged to be the real special signal. Finally, the best receiving frequency range can be chosen by comprehensive considering the results of CPA and the signal to noise ratio (SNR) of the special image signal. In order to check the validity of the chosen frequency range, eavesdropping experiments are carried out. The results demonstrate that the selected frequency range can retrieve the higher quality image than other frequency bands.

Effort-reward imbalance and video display unit postural risk factors interact in women on the incidence of musculoskeletal symptoms

This study investigated gender-specific interaction between effort-reward imbalance and video display unit (VDU) postural risk factors at work on the incidence of self-reported musculoskeletal symptoms in the shoulder-neck, lower back and upper limbs regions. A cohort of 2,431 VDU users - consisting of white-collar workers in three Canadian public service organizations - was assessed on postural risk factors and effort-reward imbalance at work. After a mean follow-up time of three years, the six-month incidence proportion of musculoskeletal symptoms in each body region was measured. Interaction was estimated with the attributable proportion of cases due to interaction. For women, two significant attributable proportions due to interaction between effort-reward imbalance and postural risk factors were observed in the shoulder-neck (64%) and upper limbs (57%) regions, while an interaction of 25%, although not significant, was observed in the lower back. No interaction was observed for men. This interaction means that, among women, when effort-reward imbalance and postural risk factors are simultaneously present, the incidence of musculoskeletal symptoms is greater than the sum of effects of the individual factors. Successful interventions on either one of these exposures would thus have the supplemental benefit of preventing cases due to interaction.

Operators’ signal-detection performance in video display unit monitoring tasks of the main control room

This study evaluated the operators’ signal-detection performance in video display unit (VDU) monitoring tasks of the main control room (MCR). So far the study of the relationship between VDU design strategy and human errors has been superficial. To validate the effect of VDUs design strategies on operating errors in the MCR, this present research adopted a within subject experimental design to develop different experimental treatments based on two types of display modes included consistent mode and mixed mode. A total of 13 undergraduate and graduate students were recruited as participants in the experiment. Dependent variables included situation awareness, reaction time, error frequency, and subjective performance. Some research support was found for the representation principles. The conclusions of this study could not only be implemented by the human-system interface (HSI) designers of a MCR in the advanced nuclear power plant (NPP) but also could be generalized to the extent that other digital workstation similar to the MCR.

Can We Trust the Answers? Reliability and Validity of Ergonomic Self-Assessment Surveys

Can We Trust the Answers? Reliability and Validity of Ergonomic Self-Assessment Surveys

Eye blink frequency during different computer tasks quantified by electrooculography

The purpose of the study was to evaluate electrooculography (EOG) as an automatic method to measure the human eye blink frequency (BF) during passive and interactive computer tasks performed at two screen heights. Ten healthy subjects (5 males and 5 females) participated in the study in a 23 degrees C temperature and 30-35% relative humidity controlled simulated office environment. Each test subject completed a 2 x 10 min active task of computer work and a 3 x 10 min passive task of watching a film on a video display unit (VDU). Both tasks included two viewing angles: standard (the monitors' upper edge was in the same height as the subjects' eyes) and low (lowered by 25 degrees). EOG signals were recorded with two Ag/AgCl surface electrodes positioned above and below the right eye, and a reference electrode was placed behind the ear. The experiments were video filmed, and eye blinks were counted manually from the video recordings and compared to the EOG measurements. The method showed a high validity to detect blinks during computer work: 95.4% of the blinks were retrieved by the EOG method and very few artefacts from eye movements were erroneously classified as eye blinks (2.4%). By use of the EOG method, the computer task was found to significantly decrease the BF by 69% compared to the passive task (P < 0.001), and a small decrease (12-14%) was found by lowering the viewing angle by 25 degrees.

The feasibility of repositioning ability as a tool for ergonomic evaluation: effects of chair back inclination and fatigue on head repositioning

Poor posture has been suggested as one of the main factors contributing to the high prevalence of neck pain in video display unit (VDU) users, but no clear association between pain and any particular resting neck posture has been found. Postural awareness of the neck, as indicated by the repositioning accuracy, may therefore be an appropriate measure and potentially useful assessment tool. The objective of this study is to examine whether posture and fatigue affect the head repositioning ability in typical VDU usage. A group of 20 healthy participants reproduced a normal comfortable posture for forward, upright and backward chair back inclinations in random order both before and after fatigue of the upper trapezius muscles. Ten repetitions of the posture were recorded for 2 s each, and the angular and translational deviations from the original head position were measured with regard to the external environment (head in space repositioning) and with regard to the trunk (head on trunk repositioning). Analysis by repeated measures ANOVA showed significant effects and interactions of fatigue and chair back inclination on the repositioning errors in the sagittal plane, which typically showed systematic trends towards certain postures rather than random errors around a mean position. While further work is required to examine the ergonomic impact of impaired repositioning ability, head repositioning is sensitive to ergonomic factors such as seating configuration and fatigue, and may therefore be a useful tool for evaluation of static working postures.

Expert assessment of physical ergonomics at video-display unit workstations: repeatability, validity and responsiveness to changes.

Inter-observer repeatability, validity and responsiveness to change were determined for an expert assessment method for video-display unit (VDU) workstation ergonomics. The aim was to determine to what extent the expert assessment of ergonomics is related to the technical measurements, tidiness and space, work chair ergonomics and responds to changes in these characteristics. Technical measurements and video-recordings before and 2 months after an ergonomic intervention were made for 109 VDU office workstations. Two experts in ergonomics analysed and rated the ergonomics of the workstations. A researcher analysed tidiness and available space. A physiotherapist classified the work chairs used according to their ergonomic properties. The intra-class correlation coefficient between the workstation ergonomic ratings of the two experts was 0.74 at the baseline and 0.81 at the follow-up. Workstation tidiness and space, and work chair ergonomics, had a strong effect on the assessments of both experts. For both experts a change in the locations of the mouse, the screen and the keyboard and values of tidiness and space and work chair ergonomics during the intervention showed a significant association with the ratings. The assessment method studied can be utilized by an expert in a repeatable manner both in cross-sectional and in longitudinal settings.

Short-Term Effects of Workstation Exercises on Musculoskeletal Discomfort and Postural Changes in Seated Video Display Unit Workers

In recent years, a number of exercise programs have been developed for computer operators in order to promote movement and to reduce musculoskeletal discomfort. Tests of the effectiveness of these exercise programs, especially in field trials, are rare. The authors tested the hypothesis that doing regular, short-term (<10 days) exercises while at a workstation would decrease musculoskeletal discomfort and increase in-chair movement (ICM). Eleven directory assistance operators (8 female, 3 male) with no recent history of musculoskeletal problems volunteered. In-chair movement was measured by tracking the center of pressure at the buttock-chair interface as subjects sat on a pressure-sensitive mat. Musculoskeletal discomfort was rated through the use of the Body Part Discomfort Scale (BPDS) and a body map. We used a revised Dataspan exercise program. Operators were tested for 2 hours, on 2 occasions: before and after doing exercises for 3- to 5-day shifts. During each test, ICM was measured during three 15-minute periods at the start of the test and at the end of hours 1 and 2. Subjects rated musculoskeletal discomfort per body part using the BPDS at 30, 60, and 120 minutes of each test. The effects of exercises on ICM and BPDS ratings were examined with a two-way repeated-measures analysis of variance with day (2) x time (3) designs. When subjects were doing their exercises, ICM was higher at the start and hour 1, and perceived discomfort was lower during each test period (start, hour 1, and hour 2). When not exercising, subjects' musculoskeletal discomfort increased over time and was higher during all test periods. Exercises done by video display unit operators while at a workstation resulted in short-term decreases in both musculoskeletal discomfort and postural immobility. These results suggest that workstation exercises may be beneficial.

Influence of memory demand and contra lateral activity on muscle activity

Computer mouse work often includes memory demands and contra lateral activity. This study simulated video display unit (VDU) mouse-work and the focus was on forearm muscle activity as a result of standardised postural loads, memory demands and contra lateral activity. Surface and intramuscular electromyography (EMG) were recorded from the right forearm muscles during finger elevation and rest with and without memory demands and with and without contra lateral activity i.e. activity of the left hand. In most situations, memory demand increased activity in the m. extensor carpi radialis brevis and m. flexor digitalis superficialis. Also contra lateral activity increased activity in situations with and without memory demands. While surface EMG level of the m. extensor digitorum communis did not increase during memory demands, intramuscular EMG level increased when memory demands and contra lateral activity was combined. Influence of memory demands and contra lateral activity were most pronounced, in situations where activity levels were small. We presume that it is not only prolonged time of active computer mouse use that is a risk for development of musculoskeletal disorders, but also the time when people interact with the computer mentally or with the ‘non-mouse hand’, while resting their ‘mouse-hand’ on the mouse.

Microbiological pollution and ocular infection in CAD operators: an on-site investigation

A large number of workers are currently employed in tasks involving the use of computer based equipment. Much research has been carried out both on prevalence and incidence of ocular and visual disorders as well as on occupational asthenopia. Less attention has been given to investigating the possibility of a microbiological pollution of Video Display Unit (VDU) workstations and to the consequent possible development of work-related ocular infections. The authors investigated the presence of bacteria and fungi on Computer Assisted Design (CAD) workstations and in the conjunctival sac of the operators.