Quote:
Originally Posted by twinklesweep
(Post 821004)
I've never before heard of a sensitivity to polycarbonate lenses. Exactly what effect do they have that is the problem? I ask because for decades my ophthalmologist has insisted that all his patients use polycarbonate lenses in their glasses, solely from the point of view of safety....
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I think it might be easier if I paste what I found on the internet...says it all better than I can!
Standard Plastic Lenses - Glass lenses provide the best visual acuity, but the thickness and weight made eyeglasses difficult to wear until the invention of the standard plastic lens. The significantly lighter lenses are considerably less shatterproof and scratch a little easier compared to glass lenses. Today, standard plastic lenses remain the most economical and commonly used material for eyeglass lenses.
Polycarbonate Lenses - Polycarbonate, a thermoplastic, was initially used for aerospace applications, but other uses quickly surfaced, such as electronic components, construction materials, and vision correction. They are lighter in weight and thinner than standard plastic lenses, and shatterproof. (Polycarbonate is the material used in bullet-proof glass.)
These lenses sound like the “Superman” of eyeglass lenses, however, they do come with some disadvantages. Polycarbonate lenses are easily scratched. (Most manufactures now include a scratch-resistance coating to protect the lenses.) Polycarbonate lenses are also prone to complaints about visual acuity and chromatic aberration, the visual distortion of colors. An anti-reflective treatment is often recommended to counter any refractive issues, but this solution only adds to the cost of the eyewear.
That brings us to price. Polycarbonate lenses can cost twice as much as standard lenses, a hefty expense to pay every 12 to 24 months on the off chance of dropping a hammer on your glasses.
Thus, the standard plastic lenses present a more practical, cost-effective alternative in most cases. However, optical professionals highly recommend polycarbonate lenses for children because of the material’s durability, UV protection, and shatter resistance. Polycarbonate lenses can withstand a child’s or young adult’s horse play and recreational activities without the threat of a shattered lens. Optical professionals may advise the use of polycarbonate lenses for an individual with vision in one eye, or prescribed polycarbonate safety glasses to an individual based on occupation.
