Surely you have already been in the situation of driving a car in the dark. In summer, this may really only happen if you had to go somewhere very late, and because most facilities, including Augenland Frankfurt, close at six or at the latest eight o’clock in the evening anyway, most people spend this part of their time rather with the family on the sofa in front of the TV. Which, by the way, is a clearly better leisure activity than still wanting to drive a car at that time—this is something not only Augenland Frankfurt can confirm. Because driving while overtired is about the same as when you are tipsy: coordination is impaired and this increases the risk of accidents.
As a rule, however, before you get a driver’s license, an eye examination confirms that you see well enough. Such an examination can also be carried out for you by Augenland Frankfurt. And especially in winter, cars are often on the road in the dark—after all, it only gets light so late and already gets dark again early. But the car has headlights, and especially in cities like Frankfurt there is also street lighting, so darkness does not cause people’s eyes any problems.
If, however, on one of your drives after nightfall you have ever noticed a driver who drives very slowly but otherwise has a normal driving style and none of those conspicuous signs such as inattentiveness by which one recognizes drunk and also overtired drivers, it may be that there is a vision problem. In such cases it is quite possible that the driver in front of you is night-blind.
What is night blindness? It is a generally known truism that people do not see in the dark. However, everyone knows that this is not entirely true: only in complete darkness are people indeed blind. When it is dark outside, or also when the light is not on in a room itself but some light shines in from the hallway, people can still see very well. Rooms in which people really see only pitch black are very rare. Much more often it happens that we have to find our way in twilight or with a few small light sources in a nighttime environment. In most cases the eye adapts to this and, when switching from bright to very weak light, can recognize contours and outlines again after about five minutes. Only sudden changes—for example because when driving you suddenly look from the dark road into the headlights of an oncoming car—are problematic, since the eye needs time to adjust.
In people with night blindness, it does not adjust at all. Why is that?
Basically the eye works with two types of cells: rods, which detect light, and cones, which detect colors. During the day and in lit rooms, the cones are particularly important for our vision. In twilight, however, they do not function because they only respond to relatively strong light. The rods are more sensitive; they already react to significantly less light and allow us to still see in half-light. However—and by this you can tell quite simply whether it is bright enough for the cones to be active—only in shades of gray.
In this lighting situation, in which it is too dark to see colors and most people therefore have the world in black and white in front of them, the night-blind see nothing at all. Night blindness can have various causes, including vitamin A deficiency, cataract, and diabetes; often it is congenital. The night-blind persons do not necessarily know that they are affected.
Since the cones function in them, those affected by night blindness are restricted only at night. When driving in the dark, these people can see only the narrow area in front of their headlights; accordingly, they have great difficulty recognizing the signs at the roadside and the course of the road. But it can be difficult to judge whether this is normal or already in the realm of a problematic visual impairment.
If you are unsure whether you are affected by night blindness, you are welcome to make an appointment with Augenland Frankfurt for a diagnosis. This should be done as soon as possible, since problems with vision—especially if untreated and without a strategy for dealing with them—pose a considerable danger, especially in road traffic as already mentioned above.
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