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- Glimne, S., et al.
(författare)
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Measuring glare induced visual fatigue by fixation disparity variation
- 2013
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Ingår i: Work. - 1051-9815 .- 1875-9270. ; 45:4, s. 431-437
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To introduce fixation disparity variance as an objective measure of visual discomfort. A higher variance in fixation disparity is indicative of more visual fatigue. This observation is based on the results from a study where we investigated how fixation disparity was affected by glare on a VDU. Participants. In total 16 subjects with normal vision participated in this study. METHOD: In a balanced repeated-measurement experiment, all subjects performed equal near-vision tasks. In addition to the condition of no glare three controlled conditions of glare were used: direct light, indirect light, and desk luminary. After each condition, the fixation disparity was measured 15 times using a computerized fixation disparity test. RESULTS: The results showed that the average (mean) disparity was found to increase towards esophoric (crossed) with the adversity of the lighting conditions, but the differences were not significant. However, when analyzing the variation (standard deviation) within the 15 measurements and comparing these between conditions, we found that the direct light condition resulted in significantly higher variation compared to lighting condition of no glare and desk luminary lighting. CONCLUSION: Based on these findings, we argue that fixation disparity variance may be a useful objective measure of visual fatigue.
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- Nylén, Per, et al.
(författare)
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Vision, light and aging : A literature overview on older-age workers
- 2014
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Ingår i: Work. - 1051-9815 .- 1875-9270. ; 47:3, s. 399-412
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In many western countries individuals will need to continue their professional careers beyond the current retirement age. This requires adaptation of the working conditions to compensate for age related visual changes. OBJECTIVE: The aim of this paper is to compile and structure knowledge concerning age related changes in visual and non-visual functions among older-age workers and to describe in what way these changes relate to light and work performance. METHOD: An overview of the literature was performed in PubMed and EMBASE concerning visual changes among elderly people, light, visual ergonomics and consequences at work. RESULTS: Visual conditions and lighting design have an impact on work performance in those over age 65 even if there are few studies available. Natural age related changes in the eyes or ocular diseases can result in reduced visual function and performance. Moreover, evidence of the importance of light and dark rhythms for circadian regulation is mounting; there are indications that the older-age population might need specific attention related to this issue. Finally, visual deteriorations might also, secondarily, induce strained postures and musculoskeletal symptoms, pain and injury. CONCLUSION: Age-related changes in the eyes and also ocular diseases among older-age people have an impact on well-being and work performance, and therefore call for reconsideration of their working conditions. Knowledge about how visual functions, light and ocular diseases is needed for work design and preventive actions.
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