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Pros and Cons of Transition Lenses

Rujuta Borkar Nov 20, 2018
What are transition lenses and what is all the craze about them? Read on to find out.
Transition lenses are a type of photochromic lenses that automatically darken when they are exposed to the sun's harmful ultraviolet rays, and come back to their original clear state once a person is away from sunlight. How do these lenses work and are there any problems involved with these eyeglasses? That is what we will be finding out here.

The Working

These lenses work because they have photochromic properties. The photochromic properties are brought about because of their ability to change tints in UVB and UV rays. These tints are made possible due to a particular patented dye that helps to activate the lens.
This dye is embedded in the form of micro-crystalline silver halides or molecules in a glass substrate. These silver halides are usually taken in the form of silver chloride and work for pieces that are made from a glass material.
Similarly, for glasses that are made from a plastic material, organic photochromic molecules are used so that the reversible effect can be achieved. These molecules are usually taken in the form of oxazines or naphthopyrans.
These lenses (or rather the properties in the lenses) react to the UV rays and begin to turn darker as a reaction to rays. These will begin to darken in less than a minute when they come in contact with the UV rays and will continue to darken very slightly over a period until they finally adjust to allow only a stipulated amount of light to enter the eye.
They do not darken to the point of turning into sunglasses. The minute a person gets away from the UV rays, the lens start to fade and come back to their normal color.

Transition lenses are said to work for all forms of glasses, including bifocals, progressives, shatter-resistant, trifocals, standard lenses, and hi-index materials as well.


Protection for Eyes

The main advantage of these lenses is that it provides for eye care by providing protection from the harmful UV and UVB rays of the sun. These rays have shown to cause varied eye diseases like cataracts, cancers, and the like.


As said before, these glasses can be worn by all types of numbers-bifocals, numbered, progressive etc. thus they lend to a multipurpose usage. Similarly, they can be used by all age groups, even children who have a number. In fact, this is a very convenient option for parents to have these made for their kids and ensure protection against the sun.


Limited Protection

Even though these lenses provide protection against the harmful sun's rays, they do not provide any protection at night, especially, from the high beams of spot lights of other vehicles. At such a time, many drivers prefer to use blue lenses because they provide for equal protection during the day and night.

Immediate Effect

It takes about a minute for the lens to change tints and become dark. So, till it reaches that stage, a person has to still bear the sun's rays. So also, after it becomes dark, it takes a little time to come back to the normal shade. So if a person does not want the sun-glass effect, he will have to bear with it, nonetheless.

Limited Usage

Transition lenses don't work in places which are already UV protected―like cars, in which case, in spite of having these specialty lenses, it provides no relief. Many doctors recommend a second pair of sunglasses to fully protect the eyes.
Transition lenses are very convenient and cost-effective, but they do come with their own set of cons. So it really is up to you to decide what outweighs the other and whether you want to go in for them or not.