Modeling of VDT Workstation System Risk Factors.

The objectives of this research were to determine the most important risk factors in VDT workstations associated with physical symptoms and to investigate the interrelationship among these risk factors. A conceptual model was first developed to describe the interrelationship among the basic components in a VDT workstation system and their possible health effects. A research model was then proposed to describe the hypothesized relationships among the following categories of variables: demographic, task, workstation design, work environment, psychosocial factors, work posture, psychological stress, musculoskeletal symptoms, visual symptoms, and general physical symptoms. A method which consisted of a questionnaire, measurement and posture analysis was then developed. A field study was conducted among daily computer users in a local industry. Ninety three VDT operators participated in the study. Factor analysis was applied to the physical symptoms to help identify the underlying factors. Multiple regression was used to determine the most important factors related to the physical symptoms and the effect of interactions among the risk factors. The four factors identified among physical symptoms are: ocular discomfort, general musculoskeletal symptoms, upper extremity symptoms, and other physical symptoms. Ocular discomfort is significantly related to screen glare; both general musculoskeletal symptoms and other physical symptoms are related to fatigue; and upper extremity symptoms are related to awkward upper body posture. Many interactions between the risk factors and their effects are identified, such as, psychosocial factors and demographic, and workstation factors and working posture. Psychosocial factors are found to interact with other variables and contribute to psychological stress. The implication of this research is that both physical and social environment need to be evaluated and the interactions among the components of a VDT workstation system need to be understood in order to determine physical symptom risk factors

Video display operator complaints: A 10-year follow-up of visual fatigue and refractive disorders

Visual fatigue and discomfort are very common complaints for video display operators (VDTs). The aim of our study was to study work-related visual symptoms in relation to refractive disorders and psychosocial factors in 3054 public employees by way of follow-ups for 10 years with periodic medical examinations with eye evaluation in the period 2000-2009. Factors related to visual fatigue were evaluated in the follow-up using generalized equation estimation. Visual fatigue was very common in VDT operators (64.03%). During the follow-up, no relationship between visual fatigue and age, sex, seniority of work, visual acuity and refractory disorders was found. Visual fatigue was significantly associated with anxiety perception in a dose-related matter (odds ratio (OR) 7.40, confidence interval (CI) 95% 1.77-31.3), psychosocial factors (OR 1.03, CI 95% 1.01-1.07), use of lenses (OR 1.34, CI 95% 1.09-1.64) and time of VDT usage (OR 1.27, CI 95% 1.04-1.53). This study confirmed that visual fatigue is common in VDT users and is related to anxiety perception, time of VDT usage, use of lenses and stress. No relationship was found between visual fatigue and refractory disorders or visual acuit

Digital eye strain:Prevalence, measurement and amelioration

Digital device usage has increased substantially in recent years across all age groups, so that extensive daily use for both social and professional purposes is now normal. Digital eye strain (DES), also known as computer vision syndrome, encompasses a range of ocular and visual symptoms, and estimates suggest its prevalence may be 50% or more among computer users. Symptoms fall into two main categories: those linked to accommodative or binocular vision stress, and external symptoms linked to dry eye. Although symptoms are typically transient, they may be frequent and persistent, and have an economic impact when vocational computer users are affected. DES may be identified and measured using one of several available questionnaires, or objective evaluations of parameters such as critical flicker–fusion frequency, blink rate and completeness, accommodative function and pupil characteristics may be used to provide indices of visual fatigue. Correlations between objective and subjective measures are not always apparent. A range of management approaches exist for DES including correction of refractive error and/or presbyopia, management of dry eye, incorporating regular screen breaks and consideration of vergence and accommodative problems. Recently, several authors have explored the putative role of blue light-filtering spectacle lenses on treating DES, with mixed results. Given the high prevalence of DES and near-universal use of digital devices, it is essential that eye care practitioners are able to provide advice and management options based on quality research evidence

Visual fatigue and the driver

The last fifty years of research on visual fatigue are surveyed, with special emphasis on results that may be important in the context of driving. Over that time, ideas about visual fatigue have varied, ranging from a broad application of the label eyestrain, to virtually any visual complaint (including poor acuity), to more specific applications of the term to mean visual discomfort associated with lengthy near-vision tasks. Much of the research reviewed concerns visual fatigue in the workplace, and places particular emphasis on extended use of video displays. One consequence of this emphasis on specific workplace circumstances is that substantial portions of the work on visual fatigue may not be fully applicable to driving. The mechanisms developed to explain workplace visual fatigue may not be strongly engaged in driving. This is especially likely for research that links visual fatigue to oculomotor changes in vergence and accommodation after near work. Visual fatigue in driving is likely to be more strongly related to mechanisms such as ocular surface irritation that may occur as a consequence of eyeblink suppression, or to declines in arousal level that may occur over the course of a lengthy drive. Research directions on possible links between visual fatigue and vehicle lighting are discussed, along with options for measurement.University of Michigan Industry Affiliation Program for Human Factors in Transportation Safetyhttp://deepblue.lib.umich.edu/bitstream/2027.42/61186/1/100999.pd

Occupational exposure to electromagnetic fields in the heavy engineering CO2 welding industry in the Mangaung Metropolitan municipality

Thesis (D. Tech. (Environmental Health)) -- Central University of technology, Free State, 2013Some epidemiological studies suggest that exposure to high levels of electromagnetic fields (EMFs) may be linked with the development of adverse health effects. However there is still controversy on this matter. Due to rapid technological growth in the modern society, employees in the welding and electrical industries are highly exposed to electromagnetic fields and may be at a high risk for developing occupational diseases. The health effects which may result from exposure to electromagnetic fields are related to the strength and frequency of the fields. This study was conducted to (i) assess the exposure levels to EMFs in the welding industry, (ii) determine the possible health risks associated with exposure levels, and (iii) develop a health and safety model to guide the industry on how to reduce exposure to EMFs. The study was conducted in one mega welding company in the Mangaung Metropolitan Municipality. Welders, fitters and office workers (88 in total) gave consent to participate in the study and completed questionnaires (ethical clearance attached). Measurements of extremely low frequency EMFs were taken in workshop A, workshop B and working offices. Measurements for magnetic fields were taken at distances of 1, 2 and 3 meters (m) from the EMFs sources. The exposure levels of magnetic fields were very high in the workshops, with welders and fitters exposed to about 7.6 microtesla (μT). Electric fields were relatively low in all workstations. Participants in the study were experiencing symptoms of ill health such as headaches, sleep disorders, fatigue and distress. The symptoms reported by the workers were similar in the both groups (exposed and control). There is no clear relationship between recorded exposure levels and the development of the reported symptoms. The health and safety model was developed to guide the industry to reduce exposure to electromagnetic fields. The model describes the implementation of engineering and administrative control measures in an effort to reduce exposure to EMFs. The model also highlights the importance of wearing personal protective equipment to shield against EMFs amongst others. This study suggests that occupational exposure to high levels of extremely low frequency EMFs may increase the risk for development of chronic diseases such as leukaemia, brain and breast cancer and other diseases among highly exposed employees. Implementation of safety measures is necessary to reduce exposure to EMFs

How visual ergonomics interventions influence health and performance - with an emphasis on non-computer work tasks

Visual ergonomics evaluations and interventions were performed on non-computer work tasks at recycling facilities, post sorting facilities and operating theatres. The results can to some extent be applicable to other professions and workplaces. The purpose of the research was to investigate the effects of visual ergonomics interventions on eyestrain, musculoskeletal discomfort, headache, and visual performance at work. Individuals with eyestrain reported more musculoskeletal discomfort than individuals without eyestrain. Factors shown to have an impact on eyestrain and musculoskeletal discomfort were the visual environment, the individual’s perceived visual ability and need for spectacles. Such findings have been reported among computer users. The results presented here show that non-computer work tasks may induce similar findings as well. Evaluations of workplaces and interventions with lighting and spectacles were performed in the studies presented in this thesis. The interventions were evaluated by direct observations such as an expert approach and by indirect observations by means of questionnaires. After the evaluation and measurement of the lighting at the recycling facilities, a number of lighting recommendations were suggested to increase visibility and reduce accident risks. For the younger postal workers in particular, better lighting reduced eyestrain and musculoskeletal discomfort. Pre-intervention, the individuals with eyestrain had lower productivity than those without; their productivity increased with better lighting. The musculoskeletal discomfort from the neck decreased especially from the static side for the postal workers after they were provided with correct power in their spectacles. It is possible to improve the work posture of presbyopic postal workers with customised sorting spectacles, in particular because using the sorting spectacles results in a decrease of the backward tilt of the head. In visually demanding work such as surgery, the luminance contrast within the visual field is essential. This is especially the case for the scrub nurse who has to look into the very bright operating light and also see the less highly lit instrument table and other important aspects in the operating room. The visual focus of the surgeons is in the operating cavity, and their eyes are completely adjusted to that level. It can take up to two minutes before their vision is fully functioning again after being exposed to the high illuminance from the operating cavity. This poses a risk if something happens in the operating room outside the operating cavity that requires good visibility from the surgeon. It is thus vital to increase the general lighting in an operating room, especially around the operating table, to decrease the luminance contrasts and facilitate the operating personnel’s visual ability. In this intervention study, the operating personnel rated the improved lighting as improving their perceived visual ability and a decreasing tiredness. All together, the studies show that visual ergonomics is a multidisciplinary science that requires a holistic approach. This thesis will hopefully contribute to increasing the awareness of the effects of a good visual environment and its benefits for the individual’s health

TFOS lifestyle: Impact of the digital environment on the ocular surface

Eye strain when performing tasks reliant on a digital environment can cause discomfort, affecting productivity and quality of life. Digital eye strain (the preferred terminology) was defined as “the development or exacerbation of recurrent ocular symptoms and/or signs related specifically to digital device screen viewing”. Digital eye strain prevalence of up to 97% has been reported, due to no previously agreed definition/diagnostic criteria and limitations of current questionnaires which fail to differentiate such symptoms from those arising from non-digital tasks. Objective signs such as blink rate or critical flicker frequency changes are not ‘diagnostic’ of digital eye strain nor validated as sensitive. The mechanisms attributed to ocular surface disease exacerbation are mainly reduced blink rate and completeness, partial/uncorrected refractive error and/or underlying binocular vision anomalies, together with the cognitive demand of the task and differences in position, size, brightness and glare compared to an equivalent non-digital task. In general, interventions are not well established; patients experiencing digital eye strain should be provided with a full refractive correction for the appropriate working distances. Improving blinking, optimizing the work environment and encouraging regular breaks may help. Based on current, best evidence, blue-light blocking interventions do not appear to be an effective management strategy. More and larger clinical trials are needed to assess artificial tear effectiveness for relieving digital eye strain, particularly comparing different constituents; a systematic review within the report identified use of secretagogues and warm compress/humidity goggles/ambient humidifiers as promising strategies, along with nutritional supplementation (such as omega-3 fatty acid supplementation and berry extracts)

Appl Ergon

ObjectiveExamine the effect of a multi-component office ergonomics intervention on visual symptom reductions.MethodsOffice workers were assigned to either a group receiving a highly adjustable chair with office ergonomics training (CWT), a training-only group (TO) or a control group (C). A work environment and health questionnaire was administered 2 and 1 month(s) pre-intervention and 3, 6, and 12 months post-intervention. Multi-level statistical models tested hypotheses.ResultsThe CWT intervention lowered daily visual symptoms (p < 0.01) post-intervention. The TO group did not significantly differ from the control group. The CWT group differed significantly from the TO group (p = 0.01) post-intervention.ConclusionWorkers who received a highly adjustable chair and office ergonomics training had reduced visual symptoms and the effect was maintained through twelve months post-intervention. The lack of a training-only group effect supports implementing training in conjunction with the highly adjustable chair to reduce visual symptoms.20112016-01-20T00:00:00ZCC999999/Intramural CDC HHS/United StatesT42 0H008421/PHS HHS/United States21963250PMC471977

Optometric management of video display terminal related vision problems

The growth of the digital market is progressively leaving a big impact on eye care professionals’ practice, whose rule is to permit a comfortable vision to their patients. Video display terminal related vision problems have drawn a particular attention, since the number of computer workers have increased over the last years. The popularity of smaller digital devices, such as smart phones and tablets, is increasing also among younger generations, as almost every child own one by the start of elementary school. Computers have also become an irreplaceable accessory, when talking about students in higher education institutes. The main objective of the thesis is to analyse Computer Vision Syndrome along with other vision related problems induced by other digital devices and a proper management of those. To alleviate the symptoms and to provide a comfortable vision, while using digital screens for several hours, optometrists have a wide selection of different treatment methods. Various researches, that approve better visual performance after the consultation with an eye care professional, have been studied. Prevention, including a proper positioning of the computer workstation or ergonomic mobile phone and tablet use, plays a significant rule. However, in the presence of the symptoms, depending on the nature of those, different approaches should be considered; the most common solutions to combat CVS are correction of refraction error, binocular and accommodative dysfunction, decreasing the amount of blue light entering the eye and dry eye management. Since the rapidly digitized world is changing people’s behaviour, the visual demands required for operating modern technology will continue to increase

The effectiveness of ergonomic training on visual display terminal operators

Bibliography: leaves 139-155.This study was conducted in order to evaluate the effectiveness of a "self-help" ergonomics-training program, which was instituted in order to reduce the risk of musculoskeletal disorders and eyestrain in video display terminal (VDT) operators