The role of vision in driving
The ability to see clearly is important for many activities, from reading menus to riding bicycles. For driving a vehicle, it is essential. A certain level of vision is a requirement for maintaining a license, and drivers need to be aware of any changes to their vision that might affect their ability to operate a vehicle safely.
Perfect vision is quite rare, especially as people age. If you go out to a street, park, or other public place, you will probably find many people wearing prescription glasses which correct some of the most common forms of visual impairment. The British Columbia government’s transportation website lists some of these impairments, including myopia (nearsightedness or shortsightedness), hyperopia (farsightedness), presbyopia, and astigmatism.
Myopia, Hyperopia, Presbyopia, and Astigmatism
With myopia, people can see clearly for a short distance, but objects far away are blurred. This type of vision loss can develop at an early age and gradually get worse, or it can come later in life as the result of an illness or a stressful time, such as an intense university course. For people with myopia, the vehicle’s dashboard could be clear but everything outside the vehicle be blurred. They could easily miss seeing a person crossing the road or fail to notice a curb at the side of a street and get into serious accidents. Laser surgery can correct myopia, at least to some extent, but it is not always completely successful.
The opposite of myopia is hyperopia, where objects at a distance are clear but nearby objects are blurred. People with hyperopia may be able to see pedestrians and curbs clearly but be unable to read the numbers on the speedometer or see when the fuel gauge is nearing the Empty mark. Although it is relatively uncommon in younger people, it can happen at any age. Hyperopia is not as dangerous for driving as myopia can be, but it can also potentially cause accidents.
Presbyopia is hyperopia related to age, and astigmatism is a kind of distorted vision caused by an uneven surface of the eye. It can cause a straight line to look jagged and make it very difficult for drivers to see lanes or the edge of the road. All of these conditions can normally be corrected with glasses or contact lenses, although vision can sometimes deteriorate to the point where lenses no longer help.
Diseases of the Eyes
Many diseases can affect the eyes, including glaucoma and cataracts. According to the Mayo Clinic’s website, glaucoma is a type of eye condition that damages the optic nerve, often because of pressure on the eye. Cataracts are the clouding of vision in the eye, much like a foggy window. Both of these conditions are normally gradual and can take some time for the affected person to notice. Similarly, diseases like macular degeneration might be hard to detect until they are far advanced.
Bright sunshine and darkness can also change people’s ability to see. The British Columbia government’s website notes that reduced contrast sensitivity in brightness or darkness can make it difficult for people to see. For example, they may not know where one object ends and another begins. Also, the Canadian Automobile Association cautions that as people age, a variety of issues can increase their problems with seeing clearly, especially at night or at dawn or dusk.
For otherwise healthy eyes, sunglasses may be enough to deal with excessive light. An important consideration when choosing glasses is protecting the eyes from glare while also being able to see the vehicle’s dashboard. Special driving sunglasses are dark at the top and light at the bottom, helping people to see in two different levels of light, but ordinary sunglasses are useful, as well.
Vision Requirements for Driving
Every transportation authority in Canada has vision requirements for people operating vehicles. Drivers who need glasses or contacts have a note on their licenses to let any police officer who stops them know to check for corrective lenses. Since vision tends to deteriorate over time, drivers over the age of eighty may also have to take vision tests every year. In Ontario, some people can receive a vision waiver for Class G licenses.
People with various diseases of the eyes may also be required to show that their vision is still good enough for operating a vehicle, and others should monitor their vision to determine when they need to have their eyesight checked. Any blurriness, reduced ability to see objects at the side of the road, or increased sensitivity to light could be a sign of problems.
Temporary Vision Issues
Even for people who normally have good vision, temporary circumstances can make it dangerous to drive. An eye infection could make driving difficult, and even excessive dust in the air could impede a driver’s ability to see. This could be a problem on gravel roads if one vehicle follows too closely behind another. Also, it is a good idea to close the windows while passing a construction zone, as the extra dust could get into the eyes and cause temporary blindness. Fog and heavy snowfall are also major factors in drivers’ ability to see, and it is often best to wait for the skies to clear before setting out on the road.
Fatigue or emotion can also cause short-term eye issues. Lack of sleep can cause the eyes to feel dry, which can make it difficult to see. With negative emotions like sadness, tears in the eyes can blur the vision as much as any disease or impairment might. If possible, drivers should avoid driving under these conditions. Asking another person to drive, taking a brief nap by the side of the road, or waiting a few minutes to calm down can be good ways of dealing with some of these vision issues.
Whether they are permanent or temporary, vision issues can seriously affect people’s ability to drive. Operating a vehicle is a very visual task, with signs to read and other road users to watch for. Drivers should be aware of anything that could affect their vision and do what they can to see as well as possible on the road.