Can You See Clearly Now?

Nearly 80% of the population in Spain has some form of vision problem, according to the report “Vision in Spain 2020.” Furthermore, 30% of people suffer from at least two vision problems, and 14% from three. Considering that drivers receive 80% of their information while driving through their eyes, this is an important issue. The main disorders are presbyopia (42%), myopia (39%), astigmatism (39%), and hyperopia (18%).

One of the biggest problems with our vision, is that it usually degrades gradually, and is not noticed. Anyone who wears glasses will testify to the difference from what is believed to be good vision, to wearing the prescribed lenses.

Therefore, it is crucial to have your eyes tested on a regular basis-

If you do use vision correction, here are some tips:

• Wear your glasses or contact lenses while driving.
• If you need to wear reading glasses, it is recommended that you use progressive lenses to better observe the information you receive through the vehicle’s dashboard.
• Sunglasses that block out excess light make driving more comfortable.
• If you experience difficulty driving at night (such as poor visibility of road signs, poor depth estimation, etc.), avoid driving at night or in poor lighting conditions (rain, fog, etc.). Plan your trip to avoid adverse weather conditions.
• Reduce speed: Increasing speed reduces your field of vision.
• If you take any medication that affects your vision, follow your doctor’s advice and avoid night driving.
• If the ophthalmologist dilates your pupils during an examination, do not drive until the medication wears off.

Human vision is very complex. As Dr. Nouzet explains in the “Manual on Neurology and Driving,” “when driving, humans must be attentive to the images processed in the central and peripheral visual fields, under different lighting conditions and, therefore, contrast between images, while moving in an environment that, in turn, includes other moving objects and, often, in adverse conditions that, in and of themselves, reduce visibility. Furthermore, human visual function is highly complex because it needs to integrate various types of information (position, size, colour, movement, etc.) to create a clear image for the brain. All in all, it’s easy to understand how visual disturbances can affect the ability to drive vehicles.”

Visual acuity (the definition or detail with which objects are perceived), visual field (the total space covered by vision when looking at a central point), and contrast sensitivity (the ability to distinguish an object from its surroundings) are basic driving abilities that can be impaired by numerous diseases or disorders, either affecting the organ of vision itself (cataracts, glaucoma, or refractive disorders such as myopia or astigmatism), or by diseases affecting other organs or systems, such as diabetes. A decrease in these abilities puts the safety of both the driver and others at risk.

During medical examinations to obtain or renew a driver’s license, the first test performed on a driver is visual acuity, specifically distance visual acuity. Good visual acuity allows for accurate observation of visual stimuli in the road environment.

The regulations allow driving with binocular visual acuity of 0.5 (with or without correction); however, drivers must be instructed that they must drive with the best vision they can achieve, and if they achieve vision better than 0.5 with glasses or contact lenses, even if not required to do so, it is essential that they wear them. Furthermore, in poor lighting conditions (at night or with poor visibility), visual acuity is reduced, and adequate contrast sensitivity—the ability to identify an object and separate it from its background (traffic signs, pedestrians, vehicles)—is required. When contrast sensitivity is impaired, driving from dusk to dawn should be avoided.

Remember also, if you wear glasses, it is a good idea to carry a spare pair with you when driving, although this is no longer mandatory, as you will be unable to drive if anything happens to the spectacles you are wearing.