Discomfort Factors

  Nature of the task
  Length of time spend at the computer
  Reduced rate blinking
  Lack of coordination between the design of the workstation and the design of the glasses or contact lenses used for the task.

Here are some examples of situations that usually increase user discomfort especially to the eyes.

  Intense tasks such as games.
  Tasks with few breaks from the screen.
  Tasks which require constant looking from the copy to screen such as data entry.
  Detailed tasks such as desk top publishing or Computer Assisted Design (CAD).
  Eye level placement of screens causes eyes to be wide open causing faster drying.
  Eye level screens are too high for most bifocal wearers unless they have specially designed glasses for this task.
  Many glasses exacerbate the restriction of movement which is a consequence of most computer tasks causing neck, shoulder, and arm problems.

The average rate of blinking is 12 to 15 times per minute. This is frequently reduced during intensive tasks, leading to visual fatigue and dry eyes. Therefore, reading from a screen reduces blinking, which in turn, leads to discomfort.