[cmeisenzahl]

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!

[dav]

i believe the higher the index of the material, the thinner the lens can be and still maintain your prescription.

[tooki]

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!

[ctt1wbw]

I just ordered two pairs of glasses from 39 Dollar Glasses.com Discount Prices on High Quality Eyeglasses and Sunglasses Online.. Fairly simple and easy to order. Including shipping was $95.

[opticstoreonline]

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.

[ajprice]

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?'