Association Between Occupational Asthenopia and the Psychophysiological Indicators of Visual Fatigue for VDT Workers

Abstract

Januskevicius Vidm antas2 'D e p a rtm e n t o f En viron m en ta l and O cc u p a tio n a l M e dicin e , K a u n a s U n ive rs ity o f M e dicin e , Lithuania, d e p a r t m e n t o f H ealth S y s te m s R e se a rc h o f Institute o f Biom edical R e se arch , K a u n a s U n ive rs ity o f M e dicin e , Lithuania To evaluate the relationship o f functional visual fatigue parameters with the symptoms o f asthenopia, and to determine associ ation between subjective and the objective indicators o f eye fatigue. 404 office workers with and without VDT work were select ed for the inclusion in the study. To evaluate visual fatigue was used questionnaire for subjective complaints and measurement of main ophtalmological indicators. Psychophysiological studies determine changes in the sensomotoric reactions during the working day and the working week; in addition to that, studies of the constancy o f clear-unclear vision and the fluctuation of the clear and unclear vision periods were performed. Measurements o f psychophysiological changes were taken over one week, three times per day, for five days in a row. The questionnaire data showed that 88.4% of all employees complained o f various vision disorders. Our psychophysiological findings showed that during the second half o f the working day, when general fatigue and asthenopia develops, ophthalmologic indications change: visual sensomotor reaction becomes slower, the duration o f the periods of unclear vision increases, and the change o f the periods o f clear and unclear vision becomes faster. Changes in the ocular and psychophysiological functions before and at the end o f the workday, as determined in our study, provide a good objective index of VDT-induced «ocular» and central nervous system fatigue, can be used for intervention research.

Prevalence of Computer Vision Syndrome and Its Relationship with Ergonomic and Individual Factors in Presbyopic VDT Workers Using Progressive Addition Lenses

“…However, a smaller pupil may reduce ocular aberrations and the amount of light scatter [46], while improving the depth of focus, which would reduce the accommodative strain. We think that these may be some of the reasons why the literature presents contradictory findings on the evaluation of the relationship between CVS and age [47].…”

Objective Evaluation of Visual Fatigue Using Binocular Fusion Maintenance

“…This finding suggests that many individuals perceive diplopia and blurred vision following computer use. 2 , 19 , 39 Earlier studies have shown that stereoacuity is best under photopic and is reduced under mesopic and scotopic conditions. 40 , 41 We set the illumination of BFM test and visual task at 270 lx.…”

“…Diplopia is the subjective complaint of seeing two retinal images of the single object and is one of the most prevalent visual symptoms associated with visual fatigue in nonstrabismic computer workers. 19 This is caused by the deviation of one eye to heterophoric posture (eso- or exo- deviation) when sensory and motor fusion are diminished 20 ; therefore, the ability to maintain binocular fusion, which merges two retinal images in the brain, 21 may be an objective parameter to represent visual fatigue.…”

Digital asthenopia: blue-blocking lenses and + 0,40D additional power in the near zone, for eye strain, accommodation and convergence functions

“…(17,18) There is currently a relative paucity of clinical evidence to support many claims surrounding the deleterious effects of blue-light exposure. (19) Although ocular discomfort symptoms have been long associated with computer and video display terminal use, (20,21) the relative contribution of blue light per se (rather than other potential causative factors, such as binocular vision anomalies, postural factors, and/or tear film dysfunction) remains unclear. (19) However, in this investigation, the subjects had their refractive errors properly corrected and did not present oculomotor diseases or accommodative or converge problems.…”