Screen Positioning

Positioning the screen optimally is critical to minimising eye strain but also to maintaining good posture and managing back strain as one of the key reasons people lean in towards their screen is to view the screen, so let’s start with distance…
 
How far should your computer screen be?  'Arms length' is something you may have heard!  Well, whose arms?  Does this mean that people with longer arms have a better eye sight?  And where does this guideline even come from and can it be used for everyone?
 
Well the answer is no, of course not.  There are a number of factors that influence optimum screen distance.  Here are a few...
·       Visual acuity (eye sight)
·       Number and size of screens
·       Font sizes used
·       Amount of data viewed
·       Type of information on screen (images/characters/numbers)
·       Lighting
·       Number/length of natural screen breaks
 
The arm's-length guideline most likely came from recommendations on monitor placement in NASA cockpits, which were associated with touch screen controls and are therefore based on reach distance.  This guideline was extrapolated for use in other guidelines.  
 
However, the evidence for 15” screens suggests a comfortable viewing range of 45-75 cm, with an average of 60cm.  Interestingly, if the screen is at arm’s length for most people, it naturally falls around the 60cm mark, so no need to throw the baby out with the bathwater.
 
The thing is, 15” screens are largely a thing of the past and when we were using them, we didn’t have the array of applications that we have nowadays.  Plus, dual and triple screen use was very rare, unless you worked in the investment banking world, so what should we be aiming for now.
 
In general, with screen distance, further is better (up to our optimum viewing distance of around 120cm), however in order to take into account the limiting factors detailed above, follow these principles:  Position the screen as far back as you can read the characters and maximize the font size as far as practicable for your role (you don’t want to cause RSI by increasing mouse scrolling to accommodate reduced information presented on the screen at one time).
 
What about the screen height?  Well, our optimum viewing distance is closer with a slight downward gaze, therefore a 30 degree downward viewing angle is recommended.  A good rule of thumb is to position the top of the screen level with your horizontal line of sight.