EFFECT:
The glass is prepared by the dark or light intensity, and this by the glass pigments. The UV radiation is the fact that pigments change as the glass and dark colors.

NUT:
The eye regulates the light by making it smaller or larger the pupil, as the operation of a camera aperture. This requires an effort of the eye. Stain glass with less effort must summon your eye to protect themselves against the light. Thus, your eye is less tired. If you do not need half glasses, which is like sunglasses!
Stain glass can have a tint or not to take. A basic tone can be useful in following circumstances: when computing, for headaches, eye fatigue and irritation!

PROBLEMS

a) SPEED
The rate of change between dark and ready is very important, because the constantly changing light intensity (or to enter when the sun disappears). A good photo chromatic glass has about 30 seconds needed to be dark and about 2 minutes to half needed to be ready. Only after 20 to 30 minutes, the glasses back as clear as possible!
 
  b) No discoloration REAR GLASS
Because windows and windshields blocking ultraviolet light, discoloring the glass behind glass is not.
Therefore, most drivers wear sunglasses or a real buy glasses with matching clip! We advise them happy Serengeti sun glasses, because they also filter out blue light, which contrasts the benefits! * Today there are drive wear glasses or fade in the car: see this link

c) TEMPERATURE SENSITIVITY:
In cold (= winter) to the glass more color, which is not always adapted. Excessive heat or cold or sudden large temperature changes can process the crystal (sometimes permanent) distort not leave your glasses behind the car window down!

d) SOMETIMES NOT EGAL DISCOLOURATION:
staining in the mass of mineral glasses are sometimes not gelijkamtige staining, because the center is thicker or thinner at high strengths. Solution: make a color layer on the glass ( "transitions process). Thus one could also kunsstof glasses to change color.

DISCOLOURATION GLASS IN PLASTIC STILL HAVE MORE ADVANTAGES:

1) Now it's the glasses, THE FASTEST, THE MOST EQUAL and the darkest color. In dark conditions, they also quickly clear, much clearer than previously possible with mineral glass.
 
  2) Moreover, 100% UV PROTECTION glass transition, even if they are not colored! This is perhaps even more important. Everyone knows that a UV radiation is harmful for the skin you can reach a burning and long term skin wrinkles and even skin cancer get. The adverse effects on eyes are less well known: the short term you irritable, red eyes get less clear that (going to "snow blindness"). In the long term, UV radiation accelerated eye diseases, such as cataract (= the clouding of the lens) and macular degeneration (= abrasion of the central part of the retina, so read and recognize details, difficult!). Ophthalmologists recommend therefore permanently protect your eyes from UV radiation, especially in people who come out and many people with little pigment (blond people with blue eyes). This applies even more to children and teenage eyes, yet so clear that all UV radiation is left! Moreover, children's pupils larger so more light in the eye falls! Also outdoor athletes are aware of the high UV load. We think especially of those who are faced with reflections from water, sand and snow. The higher and closer to the equator you go to your sport, the more UV radiation there is! Even townspeople would we recommend transitions faster than villagers. In a city you have to be confronted with bright light and UV, because the more light reflected from white walls and large glass parties!