A multidisciplinary approach to solving computer related vision problems

Neck and upper extremity pain in sonographers - a longitudinal study

Background

Sonographers have reported a high occurrence of musculoskeletal pain for more than 25 years. Assessments of occupational risk factors have previously been based on cross-sectional surveys. The aim of this longitudinal study was to determine which factors at baseline that were associated with neck/shoulder and elbow/hand pain at follow-up.

Methods

A questionnaire was answered by 248 female sonographers at baseline and follow-up (85% of the original cohort). 208 were included in the analyses. Physical, visual, and psychosocial work-related conditions were assessed at baseline. Pain in two body regions (neck/shoulders and elbows/hands) was assessed at both baseline and follow up.

Results

Pain at baseline showed the strongest association with pain at follow-up in both body regions [prevalence ratio (PR) 2.04; 95% confidence interval (CI) 1.50–2.76], for neck/shoulders and (PR 3.45; CI 2.29–5.22) for elbows/hands. Neck/shoulder pain at follow-up was associated with inability of ergonomic adjustments at the ultrasound device (PR 1.25; CI 1.05–1.49), a high mechanical exposure index (PR 1.66; CI 1.09–2.52), and adverse visual conditions (PR 1.24; CI 1.00–1.54) at baseline. Moreover, among participants with no neck/shoulder pain at baseline, high job demands (PR 1.78; CI 1.01–3.12), and a high mechanical exposure index (PR 2.0; CI 0.98–4.14) predicted pain at follow-up. Pain in the elbows/hands at follow-up was associated with high sensory demands at baseline (PR 1.63; CI 1.08–2.45), and among participants without pain at baseline high sensory demands predicted elbow/hand pain at follow-up (PR 3.34; CI 1.53–7.31).

Conclusion

Pain at baseline was the strongest predictor for pain at follow-up in both body regions. We also found several occupational factors at baseline that were associated with pain at follow-up: inability to adjust equipment, adverse visual conditions, a high MEI, high job demands and high sensory demands. These results point at a possibility to influence pain with better ergonomics.

Visual fatigue during control room work in process industries

BACKGROUND

Working in front of computer screens is visually demanding and related to adverse eye symptoms. Occurrence of glare further increases visual fatigue.

OBJECTIVE

This paper presents results from an examination of visual ergonomics in control room environments at two Swedish process industries.

METHODS

Visual conditions were examined and evaluated in nine control rooms and eighteen process operators answered questions about their perceived workload and visual experiences.

RESULTS

When working in the control rooms, the mental workload was rated significantly higher by the participants, compared to experienced performance. The operators further experienced significantly higher visual fatigue and blurred vision compared to double vision and sore eyes. Visual demands were increased in conditions where contrast glare was present, as well as frequent changes of focusing distances, and low contrast between background and characters in computer screens.

CONCLUSIONS

Suboptimal visual working conditions in the control rooms contributes to increased visual demands on the operators. Presence of glare is leading to visual fatigue and an unnecessary high mental load. The findings support the relevance of considering principles of general and visual ergonomics when designing and organizing work in control rooms. Workstation design should also be flexible to allow for individual and contextual adjustments.

Computer vision symptoms in people with and without neck pain

BACKGROUND

Sixty-four to 90% of computer users experience symptoms of computer vision syndrome (CVS). People with CVS symptoms experience neck pain (NP), and people with NP can have visual symptoms.

OBJECTIVES

(1) To examine differences in CVS symptoms in computer users with and without persistent NP. (2) To determine relationships between visual ergonomics, demographics, and CVS in those with and without persistent NP DESIGN: Comparative cross-sectional observational study METHOD: An online survey consisting of multiple questionnaires including the Computer Vision Syndrome Questionnaire (CVS-Q), Visual Symptoms Survey (VSS), and Convergence Insufficiency Symptoms Survey (CISS) was completed by 167 participants.

RESULTS

The persistent NP group had significantly higher CVS-Q, VSS, and CISS scores (p <0.01) compared to controls. No relationships were found between visual ergonomics, demographics, and visual symptoms in both groups.

CONCLUSIONS

People with persitent NP are more likely to present with CVS than controls. Clinicians should consider assessing visual symptoms in people presenting with persisting NP.

Computer vision syndrome and ergonomic practices among undergraduate university students

AIM

To determine the prevalence of computer vision syndrome (CVS) and ergonomic practices among students in the Faculty of Medical Sciences at The University of the West Indies (UWI), Jamaica.

METHOD

A cross-sectional study was done with a self-administered questionnaire.

RESULTS

Four hundred and nine students participated; 78% were females. The mean age was 21.6 years. Neck pain (75.1%), eye strain (67%), shoulder pain (65.5%) and eye burn (61.9%) were the most common CVS symptoms. Dry eyes (26.2%), double vision (28.9%) and blurred vision (51.6%) were the least commonly experienced symptoms. Eye burning (P = .001), eye strain (P = .041) and neck pain (P = .023) were significantly related to level of viewing. Moderate eye burning (55.1%) and double vision (56%) occurred in those who used handheld devices (P = .001 and .007, respectively). Moderate blurred vision was reported in 52% who looked down at the device compared with 14.8% who held it at an angle. Severe eye strain occurred in 63% of those who looked down at a device compared with 21% who kept the device at eye level. Shoulder pain was not related to pattern of use.

CONCLUSION

Ocular symptoms and neck pain were less likely if the device was held just below eye level. There is a high prevalence of Symptoms of CVS amongst university students which could be reduced, in particular neck pain and eye strain and burning, with improved ergonomic practices.

Comparison of progressive addition lenses for general purpose and for computer vision: an office field study

BACKGROUND

Two types of progressive addition lenses (PALs) were compared in an office field study: 1. General purpose PALs with continuous clear vision between infinity and near reading distances and 2. Computer vision PALs with a wider zone of clear vision at the monitor and in near vision but no clear distance vision.

METHODS

Twenty-three presbyopic participants wore each type of lens for two weeks in a double-masked four-week quasi-experimental procedure that included an adaptation phase (Weeks 1 and 2) and a test phase (Weeks 3 and 4). Questionnaires on visual and musculoskeletal conditions as well as preferences regarding the type of lenses were administered. After eight more weeks of free use of the spectacles, the preferences were assessed again. The ergonomic conditions were analysed from photographs.

RESULTS

Head inclination when looking at the monitor was significantly lower by 2.3 degrees with the computer vision PALs than with the general purpose PALs. Vision at the monitor was judged significantly better with computer PALs, while distance vision was judged better with general purpose PALs; however, the reported advantage of computer vision PALs differed in extent between participants. Accordingly, 61 per cent of the participants preferred the computer vision PALs, when asked without information about lens design. After full information about lens characteristics and additional eight weeks of free spectacle use, 44 per cent preferred the computer vision PALs.

CONCLUSION

On average, computer vision PALs were rated significantly better with respect to vision at the monitor during the experimental part of the study. In the final forced-choice ratings, approximately half of the participants preferred either the computer vision PAL or the general purpose PAL. Individual factors seem to play a role in this preference and in the rated advantage of computer vision PALs.

The vertical monitor position for presbyopic computer users with progressive lenses: how to reach clear vision and comfortable head posture

When presbyopic employees are wearing general-purpose progressive lenses, they have clear vision only with a lower gaze inclination to the computer monitor, given the head assumes a comfortable inclination. Therefore, in the present intervention field study the monitor position was lowered, also with the aim to reduce musculoskeletal symptoms. A comparison group comprised users of lenses that do not restrict the field of clear vision. The lower monitor positions led the participants to lower their head inclination, which was linearly associated with a significant reduction in musculoskeletal symptoms. However, for progressive lenses a lower head inclination means a lower zone of clear vision, so that clear vision of the complete monitor was not achieved, rather the monitor should have been placed even lower. The procedures of this study may be useful for optimising the individual monitor position depending on the comfortable head and gaze inclination and the vertical zone of clear vision of progressive lenses.

PRACTITIONER SUMMARY

For users of general-purpose progressive lenses, it is suggested that low monitor positions allow for clear vision at the monitor and for a physiologically favourable head inclination. Employees may improve their workplace using a flyer providing ergonomic-optometric information.