Why is good eyesight so important?
Good eyesight is a pre-requisite for safe driving. How many times after accidents have you heard people say "I never saw him" Driving is a highly complex task with 90% of the information our brain receives and reacts upon coming through our eyes. Our eyes are incredibly important for co-ordinating limb movements and decision making while driving.
How the eye works
To see clearly, light rays need to be focused on to the retina at the back of the eye. This is achieved as the light rays pass through the transparent cornea, then through the fine-focusing lens. The image formed on the light-sensitive retina is converted into electrical impulses, which pass through nerves to the part of the brain responsible for vision. Here, they're interpreted to tell us what we're seeing.
How we use our eyes while driving
We use both our eyes to operate the cars controls while focusing on the road ahead. Good visual accuracy affords us the ability to clearly see detail and good visual acuity helps us to identify other vehicles, road signs, cyclists, pedestrians.
Peripheral vision provides us with the ability to look all around the inside of the car without moving our heads. This ability allows us to simultaneously look through the front windscreen, the front side and the rear passenger windows; and to use the rear and side mirrors without taking your eyes off the road.
Depth Perception is the ability to judge spatial relationships of objects. For example, the distance between your car and vehicle in front or judging the gap between two parked cars. Depth perception depends on good binocular vision; it is particularly important when judging whether it is safe to overtake or when it is safe to move from one lane on the motorway to another.
Our retinal photoreceptor cells provide us with wide-angle peripheral vision which affords us good night-vision, even in very dim light. Being able to focus in dim light and to see further than your headlights adds to the safety of night driving. Night vision declines with age; if you find the glare from oncoming headlights difficult to recover quickly from; you should consult your optician to see if night-time driving glasses are advisable.
Why is good eyesight important?
Safety Advice for older drivers Tips and Advice - Article No.14 RoadDriver 2010
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