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N. one has any real idea how many people driving on the roads are no longer capable of legal vision. And there is another and probably much larger group that need to use contact lenses or spectacles to achieve legal vision, but who choose not to wear them when at the wheel.
In some countries a driving licence contains a photograph and if the driver needs spectacles and is not wearing them when stopped by the police, action can he taken against the driver.
The ultimate prudent attitude for truck drivers is to assume when encountering other road users that the other person may be effectively partially-sighted and that this includes other drivers and pedestrians.
From the point of view of self-help there are several things that are well worth doing. First, always carry a spare pair of spectacles or contact lenses. The old ones will do.
Prevent ghosts
Second, have spectacle lenses with good antireflection coatings. These prevent ghost images, formed by reflections of headlamps and street lamps from the surfaces of the spectacle lens, reaching the eye. They also prevent light from headlamps of vehicles behind your vehicle from bouncing off the rear surface of your lenses into your eye.
Third, have nothing to do with amber night-driving glasses. Sunshine is yellow. Everyone enjoys sunshine and when there is a lot of light you can see better. In hazy conditions an amber filter improves contrast in photography.
Thus , so the twisted logic runs, if an amber lens is in front of the eye it will enhance contrasts (this assumes that the eye operates on silver-based photographic emulsions, which it does not). Amber filters absorb light and cannot improve night vision.
Fourth, if you use sunglasses make sure that they (=form to BS 2724/1987. One of the requirements of this standard is that the sunglasses do not significantly distort signal colour values as some sunglasses have done in the past.
The most effective sunglasses for driving are polarising sunglasses and the original Polaroid company has always had a very high standard of quality control. These lenses are very effective in cutting out horizontal glare from a polished, or wet road, when the sun is ahead and low in the sky The British company Pilkington Special Glass produces the best photochromic glass in the world. It darkens in sunlight and clears almost completely in darkness.
Forget the bunkum that has been put out that if you drive into an unlit tunnel, the photochromic glass will not clear sufficiently. Those academics that leapt to denigrate a British product were unaware that inside a vehicle the temperature is high and photochromic materials do not darken unduly in such circumstances.
Moreover there is only about 10% as much light inside a vehicle as there is outside a vehicle. In any case, there are no unlit tunnels in the UK. I found some in Spain and drove into them wearing Pilkington Reactolite lenses without inconvenience.
It is a myth that photochromic glass is too dark in tunnels. It is true that plastic lenses scratch more easily than glass. Plastic photochromic sunglasses work less well than British glass photochromic sunglasses. Pilkington is thought to be working on a new React°lite lens which also incorporates a polarising filter and a prescription component. If you have an optical prescription and you are a professional driver it is worth considering sunglasses made to your prescription.
There are a number of points to be considered about night driving.
Truck drivers suffer less from glare from approaching headlamps because they are high up and so above the oncoming beams.
But they only have headlamps for one rule of the road. So if they are involved in Continental driving they will not be able to see as much as they should along the kerbside of the road for much of the time — they need two pairs of differently-handed headlamps.
lithe driver of a tractor unit is going to be able to see properly without causing glare to other road users, the tractor unit need headlamps that take account of empty running and running with a full load .
Driving a solo tractor unit at night can be very exciting. Not only is the vehicle fast and skittish, but the headlighting is pointing down at the roadway a short distance ahead. When a fully laden trailer is in tow the headlighting on main beam may do rather better in picking up low flying aircraft than illuminating the roadway ahead.