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Wearers of prescription eyeglasses appreciate the clarity of sight that is restored to them every time they put on their glasses. At the same time, many of those who must wear corrective lenses privately lament the inconveniences that accompany the ownership of eyewear.

One common inconvenience that is especially experienced in sunny areas is the need for those who use corrective lenses to own two pairs, one for use inside buildings and another pair of prescription sunglasses to use while driving and doing other outdoor activities. Because neither pair of lenses is worn at all times, it is easier to lose one set or leave it behind at home. Furthermore, there is the added expense of owning two pairs of prescription eyewear, which certainly is undesirable in a day when all of us are looking to save an extra dollar or two.

In the past, wearers of eyeglasses did not have any alternative to owning two pairs of lenses. Beginning in the 1960s, however, eyeglass manufacturers began developing technology that could integrate sunglasses and ordinary eyewear into one package. Photochromic lenses provided the breakthrough in enabling the lenses that are worn inside also to be the lenses that can shield eyes from the damaging effects of sunlight.

Photochromic eyewear use special lenses that have the ability to darken in sunlight and then lighten when worn indoors. Tiny molecules of compounds like silver halide or silver chloride are mixed with the lens material and these molecules undergo certain transformations under the proper conditions. Ultraviolet light such as is found in direct sunlight makes the shape of these molecules change and absorb visible light, resulting in the darkening of the lens. Such molecules revert to their original form when ultraviolet light is absent, making the lenses clear once more.

These photochromic molecules were first integrated into glass lenses in the 1960s, but they are now used as well in the production of plastic lenses for designer eyeglasses or eyewear that is not quite as costly. Integration is achieved most commonly through bathing plastic lenses in a bath comprised of silver halide, silver chloride, and other photochromic materials. With photochromic lenses, one set of eyewear can suffice for both indoor and outdoor use, giving the consumer both convenience and savings. After all, it is always less expensive to buy one pair of lenses than it is to buy two.

Today, people all over the world enjoy the many benefits that come with owning a pair of photochromic lenses. These helpful tools are not only practical but also stylish, and many high-end manufacturers incorporate them into their fine eyewear, but one does not need to break the bank to afford a set of lenses with these properties, as the many fine specimens of inexpensive but effective photochromic eyewear testify. Those who are looking for a pair of lenses that can perform double duty are encouraged to look into purchasing photochromic eyewear for them in order to experience the convenience and quality of these lenses.

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