Near vision accommodation in horizontality with VDT: why low blinking and dry eye?

Abstract

Users of current computer Visual Display Terminals (VDT) frequently complain of eye dryness, ocular surface redness, eye itching, burning, irritation, sandiness, headache, glare, neck pain, fatigue and tiredness. 1-6 These same users do not feel these symptoms when reading a book. In this study we examine different positional changes of the eyes and head during both plesiovision, i.e., downward gazing near vision, and horizontal near vision. As VDT occupy a large volume of space, they are generally placed on office tables in a vertical position, obliging the users to look at them horizontally. This study presents the positional changes of the eyes when focusing from a distance (teleopsis) with the eyes in a horizontal position, when focusing near (plesiopsis) with the eyes gazing downward, and when focusing near with the eyes in a horizontal position.