On the preferred viewing distances to screen and document at VDU workplaces

Abstract

Abstract Previous research has shown that during work at visual display units (VDUb) most subjects prefer viewing distances greater than 50 cm. The present study investigates whether this is also true in those VDU tasks that require the subjects to shift their gaze frequently between the VDU screen and a paper document. In a laboratory VDU task two conditions were compared: one in which both screen and document were located at the same viewing distance of 50 cm (as recommended in most ergonomic guidelines) and another in which the distance to the document was 50 cm and the distance to the screen was 70 cm. Gaze shifts between screen and document were made every 2 s. Visual strain of 20 subjects aged 19-51 years was estimated with a questionnaire. Contrary to expectation, visual strain was not greater when the viewing distances to screen and document differed. Thus, the dynamic load on accommodation and convergence due to the different viewing distances (50 and 70 cm) did not produce stronger visual strain...