Workplace interventions to prevent musculoskeletal and visual symptoms and disorders among computer users: a systematic review.

BACKGROUND: The literature examining the effects of workstation, eyewear and behavioral interventions on musculoskeletal and visual symptoms among computer users is large and heterogeneous. METHODS: A systematic review of the literature used a best evidence synthesis approach to address the general question "Do office interventions among computer users have an effect on musculoskeletal or visual health?" This was followed by an evaluation of specific interventions. RESULTS: The initial search identified 7313 articles which were reduced to 31 studies based on content and quality. Overall, a mixed level of evidence was observed for the general question. Moderate evidence was observed for: (1) no effect of workstation adjustment, (2) no effect of rest breaks and exercise and (3) positive effect of alternative pointing devices. For all other interventions mixed or insufficient evidence of effect was observed. CONCLUSION: Few high quality studies were found that examined the effects of interventions in the office on musculoskeletal or visual health.

Dynamic visual fields of one-eyed observers.

BACKGROUND: The horizontal binocular visual field can extend to more than 200 degrees, while a monocular field is limited to 160 degrees. Additionally, the nose and other facial structures may block the monocular field further during certain eye movements. The purpose of this study was to compare the monocular against the binocular visual field and determine if head and eye movements can functionally overcome any measured deficit. METHODS: In Experiment 1, visual fields were measured monocularly with a bowl perimeter using 5 fixation positions. Binocular visual fields were calculated by combining the monocular visual field with its mirror image. In Experiment 2, subjects were allowed to make head, eye, and body movements to search for flashing lights 360 degrees around them, spaced every 45 degrees. The numbers of lights identified were compared for the subjects performing monocularly versus binocularly. RESULTS: The size of the overall monocular visual field was found to vary between 48% and 76% of the binocular visual field, depending on eye position. For the flashing light experiment, head and eye movements could not overcome the entire visual-field deficit with monocular viewing. Monocular performance remained 11.4% less than binocular performance. CONCLUSIONS: The visual-field deficit seen with monocular viewing is greatest with nasal fixation, and head and eye movements cannot totally compensate for this deficit when viewing time is limited. Vision standards that require full visual fields in each eye are more appropriate for occupations in which peripheral visual targets must be identified and visual search time is limited.

Productivity associated with visual status of computer users.

BACKGROUND: The aim of this project is to examine the potential connection between the astigmatic refractive corrections of subjects using computers and their productivity and comfort. We hypothesize that improving the visual status of subjects using computers results in greater productivity, as well as improved visual comfort. METHODS: Inclusion criteria required subjects 19 to 30 years of age with complete vision examinations before being enrolled. Using a double-masked, placebo-controlled, randomized design, subjects completed three experimental tasks calculated to assess the effects of refractive error on productivity (time to completion and the number of errors) at a computer. The tasks resembled those commonly undertaken by computer users and involved visual search tasks of: (1) counties and populations; (2) nonsense word search; and (3) a modified text-editing task. RESULTS: Estimates of productivity for time to completion varied from a minimum of 2.5% upwards to 28.7% with 2 D cylinder miscorrection. Assuming a conservative estimate of an overall 2.5% increase in productivity with appropriate astigmatic refractive correction, our data suggest a favorable cost-benefit ratio of at least 2.3 for the visual correction of an employee (total cost 268 dollars) with a salary of 25,000 dollars per year. CONCLUSIONS: We conclude that astigmatic refractive error affected both productivity and visual comfort under the conditions of this experiment. These data also suggest a favorable cost-benefit ratio for employers who provide computer-specific eyewear to their employees.