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Rx lenses questions ...
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Grizzled Veteran
Join Date: Feb 2005
Status:
Offline
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About to order some sunglasses from Zenni Optical. I have my PD and my RX, but what the heck is this Refractive Index business?
There are choices like:
1.57 Mid-Index Single-Vision
1.50 Standard Single-Vision, No Charge
1.50 Standard Single Vision
1.59 PC(Polycarbonate)Single-Vision
What do I want if I'm getting them for sunglasses? I checked and they all block UV rays, I just need to specify the tinting I want.
Thanks!
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Mac Elite
Join Date: Dec 2000
Location: sic semper tyrannis
Status:
Offline
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i believe the higher the index of the material, the thinner the lens can be and still maintain your prescription.
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one post closer to five stars
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Admin Emeritus
Join Date: Oct 1999
Location: Zurich, Switzerland
Status:
Offline
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Correct. A higher index means less curvature is needed to make the prescription, which means thinner (and therefor lighter) lenses. That said, for weak prescriptions, the difference is so small as to be immaterial.
What is material is that the polycarbonate lenses are harder to scratch.
FWIW, I have such a strong prescription that I have 1.7something high-index lenses to keep them light. I also have premium anti-reflective/anti-scratch/dirt-repellent coating. All in all, they're $500 lenses. It's also time for new ones, it's been about 4 years!
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Mac Elite
Join Date: Jan 2001
Location: Suffolk, VA
Status:
Offline
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Fresh-Faced Recruit
Join Date: Aug 2010
Status:
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Index of the lenses determines how how thin the lenses will be. If your prescription is normal you can opt for 1.5 index lenses but if your prescription is high like -4 or above then opt for higher index lenses as these lenses will be thinner and lighter. Always remember to select Anti reflective coating on high index lenses.
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Professional Poster
Join Date: Dec 2000
Location: UK
Status:
Offline
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Originally Posted by ctt1wbw
I just ordered two pairs of glasses from [url=http://www.39dollarglasses.com]39 Dollar Glasses.com ... Including shipping was $95.
Are they also known as 'I Saw You Coming?'
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It'll be much easier if you just comply.
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Fresh-Faced Recruit
Join Date: Aug 2012
Status:
Offline
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I am trying to order some glasses from this Zenni site as well my prescription is -75 in both eyes which lenses should i get??
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Clinically Insane
Join Date: Dec 2000
Location: Caught in a web of deceit.
Status:
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Originally Posted by ajprice
Are they also known as 'I Saw You Coming?'
Why? 2 x $39 = $78. That means shipping was $17, for a total of $95.
However, note that some of these cheap lenses have coatings that wear off pretty easily. Or they may have no coatings at all.
A colleague went to Lenscrafters and got the cheap American Optical lenses with their standard coatings within a year the coating was starting to wear off. It looked totally awful.
High quality Nikon or Zeiss (or other) lenses with high quality coatings are much, much better. High index are basically mandatory for strong prescriptions, or else the lenses will look like coke bottles.
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