Eye sight can be seen (pun very much intended) as being comprised of two main functions: central and peripheral.
Most associate central vision with focusing on particular objects of interest, while peripheral vision is when something to the side attracts attention. Both act as a function of the human retina, which is made up of two types of photoreceptors: rods and cones. Rods are responsible for vision at low light levels, while cones are active at higher light levels.
However, both central and peripheral do much more and provide use that many may not be aware of.
Central vision is probably the one that is more straightforward. Perhaps regarded as the more important of the two, central vision is responsible for most of the active functions that someone uses.
Reading, driving, recognising colours and shapes, and general focus-based detail-oriented sight tasks are fulfilled by the use of central vision.
This all comes from the very centre of the retina at the back of the eye, also known as the macular and is where there is a high concentration of cones. If this area is damaged, it can cause vision to become blurry and dull. Eventually it may lead to dark patches appearing.
The general public are often aware of the importance of peripheral vision. It is not something that people actively use, but this doesn’t mean that it is less important than central vision.
Peripheral vision helps to process spatial information received through the eyes and is an important cog in our innate fight or flight response system.
Any activity that involves space (and many ones that don’t) can be improved with better peripheral vision. This is due to spatial information combining with body mechanics to produce correct and precise movements.
For example, if someone is dribbling a football towards a goal, their peripheral vision can inform them of an impending opponent coming from the side. Good peripheral vision gives the player the opportunity to avoid the challenge posed. Bad peripheral vision may leave the player dining on dirt.
Light sensitivity is also associated with peripheral vision. People will often see better in low light situations with their peripheral vision rather than looking straight with their central vision. This is largely due to the increase in rod density in the periphery which are more sensitive to light.
In addition, peripheral vision plays an important part in scene gist recognition, allowing the individual to access related long-term memory with just a single eye fixation. This then helps to guide the individual in their subsequent actions.
With central vision loss being one of the most common causes of blindness, more and more people are left to rely on actively using their peripheral vision, something that may not be as intuitive. Fortunately, it is possible to train and improve peripheral vision usage to help replace some of the functions that central vision performed.