From John Tiffany, University of Oxford
As your correspondent points out, the advice to remember to blink frequently
while using a computer is not at all silly
(Letters, 18 July, p 56). The problem
of fixating on the screen and forgetting to blink is well known, and much effort
has been directed towards encouraging better ergonomic practice.
In particular, putting the computer on the desk and the screen on top of that
may mean that many operators are looking up to the screen and widening their
eyes in doing so.
Instead, we are advised to lower the screen relative to the keyboard, so that
the direction of gaze is between 10° and 15° below the horizontal. One
effect of this is a reduction in the exposed area of the eye, so evaporative
loss is reduced. It has also been found that this smaller opening results in a
thicker tear film.
These two effects greatly improve the stability of the film, and reduce the
risk of occasional film break-up and the formation of damaging dry spots on the
cornea.
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