Understanding the impact of vision upon overall performance requires a greater understanding of vision itself.
Most importantly we need to appreciate two distinct aspects of vision – the WHAT and the WHERE.
When we direct our attention and turn our eyes towards an object of interest this function is linked to the central macula area of the retina which provides us with detailed information about WHAT we are looking at.
The rest of the retina is more involved in spatial orientation and position awareness or WHERE achieved because 20% of nerve fibres from the peripheral retinal actually travel to the posture and balance areas in the mid and lower brain, rather than higher visual centres involved “seeing”. This system allows us to integrate and organise visual information with feedback from body movement and balance mechanisms of the brain.
This feedback loop is essential in providing information about WHERE we are in space and about WHERE we are looking critical before we can usefully process information about WHAT we are looking at.
For example, there would be little value in identifying a cup within our field of view if we could not also determine that it was on a table and within easy reach a little to our left.
Here are more examples of why WHERE is just as important as WHAT and can even change the WHAT into something else!
What if you could identify the ball but not WHERE is was in relation to you? Could you kick it?
What if you could see the slalom pole but not WHERE it was? Could you confidently avoid it?
What if you could not rely upon your visual system to tell you exactly where the stepping stone was? Might you step on the sloping edge rather than the flat centre? Would that make you overly cautious or slow?
What if you didn’t perceive the edge of the shelf to be exactly where is actually was or the door frame or the ground? Might you bump your head, or your shoulder or trip? So called clumsy behaviours are most often the result of a difficulty in the WHERE aspect of vision.
And how might the WHERE aspect of vision impact upon reading and spelling? It is important that you should be able to see small detail. However, in Behavioural Optometry it is equally important that you can see things EXACTLY where they are and in context.