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Mr Alan
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I never recommended that anyone use glass lenses. But there is a big difference in optical quality between polycarbonate and other "plastic" lenses. Although, polycarbonate does work better in frames which required drill mounts, the optical quality is poor. That might not matter much to those with a mild Rx, but the effect of the poor optics is much worse with a high plus or high minus lens.
"Regular Plastic" lenses are considered to be 1.50 index (known as hard resin or CR-39). Other lenses made out of plastic can have an index of 1.53 up to 1.71, and the optical quality suffers as the index gets higher (but the lens is thinner and lighter as the index gets higher).
Polycarbonate is a special kind of plastic with an index of 1.59. It has very high tensile strength and high impact resistance, but has the worst optical quality of almost any lens on the market. Many opticians will recommend them for drill mounts, but they only care about the warranty of the frame and lenses and don’t really care about your poor optics.
Many plastic 1.60 and higher index lenses can be safely drill mounted for rimless frames, but this depends somewhat on the skill of the lab who mounts the lens. Some frames are more susceptible to problems with drill mounts unless the glasses are handled with extreme care.
If you really had glass lenses, then I would be surprised since they are fairly unusual these days.
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Bangkok Girls : Meet Attractive Thai Girls
Posted on: 10:29 pm on Dec. 30, 2004
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Latrell
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As a price reference, I just had new glasses made in Siam center (Saint Peter optical) : modern Oakley frames+1.67 lenses at 12300 THB.
Other models for instance Nike AF 6000 with 1.67 lenses would have costed around 11000 THB.
The price is about the same I would have paid online in US$ with e-shops such as framesdirect.com but you get the advice and all the time to try different models.
Latrell
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Bangkok Women : Meet Sensual Bangkok Women
Posted on: 6:53 am on Nov. 23, 2008
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