Did you know that a whopping 90% of the information you receive while driving comes from visual inputs? Most people have the misconception that as long as they can see clearly, they are good to drive. It is estimated that 1 in 14 drivers have a vision defect that may affect his or her driving. To be a good and safe driver, you need to score well in four major aspects of sight — visual acuity, peripheral vision, depth perception and colour vision.
Most definitions of good eyesight are based solely on the clarity or sharpness of vision, also called visual acuity. Visual acuity is a measure of how well you can see at a specified distance in both bright and dim conditions. With good visual acuity, you can spot a target at far distances and therefore have more time to react. A binocular visual acuity of at least 6/9 is recommended for drivers. This means that, given the same target size, the clarity of what you can see with both eyes at 6 metres is equivalent to what a person with normal vision can see 9 metres away.
Our peripheral or side vision is the field of view outside the central area of focus. Peripheral vision is very important to drivers as they navigate smaller roads with high human traffic, and is critical for turning and switching lanes while driving.
Person with full peripheral vision
Person with impaired peripheral vision
The ability to see the world in three dimensions and judge the distance of an object is known as depth perception. If you have poor depth perception, you are likely to misjudge how far your vehicle is from other vehicles when changing lanes or how much space you have from the rear and sides when parking your vehicle. People who have recently lost vision in one eye should refrain from driving for at least six months so that they can adapt to changes in their depth perception.
Our colour vision plays an essential role in everyday driving. Traffic lights, indicator signs and hazard lights are coloured. Thus, people with more severe colour vision defects may have slower reaction times because they rely on other ways to process the perceived colours. For example, they may instead rely on the position rather than colour of traffic lights (red on top and green at the bottom), or observe differences in brightness to understand a signal.
Ageing and driving
It is natural for your eyesight to gradually deteriorate as you age. You may have trouble focusing on moving objects, seeing at night or in low light conditions, or dealing with bright glare from the sun or oncoming headlights. With age, one becomes susceptible to eye problems that can seriously impede your driving skills.
Here are some safety tips for driving: