[Asthenopia and work at video display terminals: study of 191 workers exposed to the risk by administration of a...

VDT (Visual Display Terminals) are commonly used in a wide range of occupational fields. Over the last ten years a number of studies have shown that ocular symptoms are the form of discomfort most frequently experienced by subjects who work at VDT. The symptoms as a whole characterize a complex syndrome named "asthenopia" and have been seen as a consequence of prolonged, fixed and closely oriented vision. In our study we have evaluated data derived from a standardized questionnaire (a series of questions elaborated and promoted by the Italian Society of Occupational Medicine and Industrial Hygiene). It was administered to a group of 191 workers who utilise VDT for more than 20 hours each week. We also took into consideration the results of ophthalmologic medical examinations performed on this particular group of workers. Prevalence of occupational asthenopia we found to be lower in this group than in the case of other reported investigations, though it proved to be higher in the case of female subjects. According to the Literature, symptoms intensity is related to the duration of weekly VDT use, there being no significant association with the number of years spent working at VDT. Our results show that prevalence of asthenopia was not significantly influenced by refractive alterations and this unexpected outcome might be explained by taking into account the small-size group of subjects affected by hypermetropic defects. It is well known that these are the most important factors in conditioning asthenopia. Our finding indicates the need for further research, which should include a larger group of VDT workers with refractive alterations and furthermore take into consideration environmental variables such as climate and illumination, since these are co-aetiological factors, known or suspected, of occupational asthenopia.