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Breaking down base curves, pupillary measurements

Tips for purchasing eyeglasses online and in stores

ORLANDO, Fla. – A $10 price tag for a pair of eyeglasses is hard to turn down. 

However, a Local 6 investigation into discount online eyeglass retailers found shortcomings with purchasing glasses online.

For instance, an optician found flaws with the base curve of the frames.

According to Carol Card at Card's Opticians in Winter Park, an optician would normally look at your old glasses to determine what base curve to use on your new frames.

The base curve is not something that is given as part of your prescription from the eye doctor. An optician would determine which base curve to use for your lenses based on how the frames sit on your face. 

"If you are not there, how could you possibly know because every pair of glasses sits on your nose differently," said Card.

Online retailer Zenni Optical said in an email to Local 6 that they use a 4 millimeter base curve as a standard.  

According to a continuing education manual prepared by the National Academy of Opticianry, the base curve should stay the same for every pair of glasses unless there is a severe difference in the client's prescription from eye to eye.

Card said that opticians should always ask to see your old pair of glasses before ever making a new set and pointed out that it something that cannot be done when ordering from an online retailer.

However, if consumers chose to go with the inexpensive online glasses, she said it is essential that they have the correct pupillary measurement, or PD. The PD is the distance between each pupil. 

A doctor can provide the measurement at an eye exam, but it is not part of a conventional prescription so the patient has to ask for it.

Sites like Zenni Optical give instructions on how to have someone measure a PD, but Card said if it ends up incorrect, you can experience eye strain.

In addition, both doctors and opticians cautioned against utilizing internet sites to order progressive eyeglasses because the measurements have to be so exact.

"If it sits too high or it sits too low, you aren't going to know," said Card.

She also said that just because you go to an eyeglass store does not mean an actual optician is fitting you for your eyeglasses.

"Florida law only requires one licensed optician to be on staff at all times, so the person you see could just be a sales associate with no more knowledge than someone reading your story.   If you go to a doctor's office where they sell eyeglasses, the law does not require a licensed optician to be on staff," she said.

Card encourages consumer to always ask for a licensed optician wherever they go to purchases glasses. 


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