Transition eye glasses are made up of sensitive photo chromatic lens capable of changing its color depending on the intensity of sunlight available. Usually a transition lens change color when they encounter UV rays from the sun. It gets more darken as the UV rays grows stronger but remains colorless when there is no UV radiation. Thus they look like ordinary glasses during night. Each time you use the lens there is a decrease in the count of its micelles and when all the micelles are gone the lens stops changing its color. The expectancy of a transition ranges from two to three years depending on their use in such environment and their quality.
Nowadays a transition lens is made up of a range of material which is light in weight. High index lenses, poly carbonate lens, Trivex, regular plastic or glass lenses are some of its kinds. Among them poly carbonate is the safest for young kids. These lenses have a variety of color such as red, blue, brown, grey etc. and there are a few lenses with no color as well. Grey is the most popular one which is capable of shielding even sunlight. Transition eye glasses with progressive and bifocal lenses are also available easily in the market.
Although it reduces your need of using prescribed sunglasses but it’s never substitute to a sunglass.In comparison to sunglass a transition lens ensures UV 400 protection which is almost sufficient but they cannot prevent HEV (high energy visible )light from entering the eye. You can have macular disease if you are prone to HEV light. Moreover if you are sitting behind a UV protected glass shield, a transition lens will not work and you may have irritation in your eyes when you enter a room from outside. Transition eye glasses are good when you have both indoor and outdoor work. But if you have out work mainly then sunglass is best option.
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