The muscles in your eyes work to keep the light entering your eyes at a comfortable level. If there are areas of high contrast in your work place your eyes work hard to adjust to the different levels of light. Also, a very bright light source in your field of vision can cause visual discomfort, and reflections on your computer screen can make it difficult to see what is displayed.

• Try to position your desk at right angles to a window. If the window is behind you there will be light reflected in your screen, while if it is beyond your screen it will be a bright light source in your direct line of sight. Remember, even on an overcast day daylight is still very bright compared to indoor lighting.
  
  
• Use blinds or curtains to reduce bright light from windows.
  
  
• Keep the overall lighting level in your work (ambient lighting) place up. Recommended levels for office based tasks are between 300 and 500 lux.
  
  
• If the overhead lights are reflected in the screen turn them off (or remove the problem tubes) and use different types of lights to increase the ambient light e.g. uplighters, lights with better diffusers.
  
  

• Use an individual desk lamp to cast extra light over your documents.
  
  
• Make sure desk lamps are not shining in your eyes or those of people sitting nearby.