In summer, when the days are sunnier and the intense light is reflected on the windshield of the car, it is essential to take care of your vision behind the wheel. Direct sunlight can dazzle the driver and prevent him from seeing properly for a few seconds, which can lead to an accident with fatal consequences.
One of the most important safety elements for driving on the sunniest days, especially in summer when the sun’s rays are more intense, are sunglasses. It is a complement that goes far beyond its aesthetic function, since they are essential to maintain a good vision on the asphalt as they help to avoid the fearsome glare.
The General Regulations for Drivers establish that, to get behind the wheel, they must do so with a minimum binocular visual acuity of 0.50 in both eyes, with or without optical correction. In other words, every driver must demonstrate a minimum vision of 50%, either naturally or by correcting it with the use of glasses or contact lenses, although it is recommended that he do so with the best vision he can achieve. It should not be forgotten that approximately 90% of the information that the driver uses to make decisions comes from sight.
However, the law does not implicitly refer to the protection that drivers must adopt to protect their eyes from the sun’s rays. Explicitly, article 18.1 of the General Traffic Regulations states that the driver of a vehicle “is obliged to maintain their own freedom of movement, the necessary field of vision and permanent attention to driving, which guarantee their own safety, the of the rest of the occupants of the vehicle and that of the other road users”.
The General Directorate of Traffic (DGT) recommends in its publications to protect the eyes from glare that may be caused by the sun’s rays in order to maintain “the necessary field of vision” referred to in the aforementioned article 18.1 of the General Traffic Regulations. Of course, remember that those who need prescription lenses to drive must also use prescription sunglasses to get behind the wheel.
Currently, there are three types of sunglasses that are sold in opticians and other establishments dedicated to the sale of lenses. They are tinted or coated, polarized and photochromic. Only the first two are advisable to drive, but not the photochromic ones.
The DGT recommends using sunglasses with a filter between 1 and 3 for daytime driving, in accordance with the advice of Professor Amalia Lorente, from the Faculty of Optics of the Complutense University of Madrid. This expert, in statements collected by the magazine Tráfico y Seguridad Vial, indicates that the sunscreen depends on the luminance to which the driver is exposed and that, therefore, a specialist should be consulted. “A street in New York, with tall buildings, is not the same as another in Torrelodones, with chalets and low houses,” she explains graphically as an example.
Lorente, however, points out in the aforementioned medium that “a category 4 filter (reserved for winter sports) can never be used to drive.” Driving with this type of glasses or with photochromic lenses carries a risk in very specific situations. For example, when entering a tunnel. “Vision is seriously compromised, since they reduce the passage of light so much (category 4) that it is like driving blind, and the long adaptation time of photochromic lenses (3-5 minutes) dangerously reduce vision,” says the statement. ‘Traffic and Road Safety’ magazine.
With regard to the color of the lenses of the glasses, the professor at the Complutense University generally recommends using gray, brown or green filters. These are three tones that do not alter the perception of color. In the case of browns, they increase contrast, and in greens, they not only increase contrast, but at the same time reduce glare and eye fatigue. In prolonged uses, a pink filter can be used.
