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pondelok 17. októbra 2011

Ordering Prescription Glasses Online

You know you have thought about it. Compare the prices at different websites to what you see inside any optical, and the price difference is usually staggering.  And people order their contact lenses off the internet all of the time, right?  Ordering glasses from internet providers is a growing trend, but as its popularity rises so do the number of complaints.  Here is an honest look at some of the pros and cons of ordering glasses off the internet:

Pros:
  • PRICE.  Some websites even offer designer frames for incredible discounts.  And the costs of lenses are much less expensive as well.  It is possible to save near a hundred dollars off typical optical costs.
  • EASE.  Well nothing can be easier than shopping from your seat.  You just pick your frame and enter your prescription, and then swipe your card. No trip outside of your living room necessary (as long as you already have a copy of your Rx).
  • SELECTION.  Let's face it, optical displays can be overwhelming.  And different offices offer differ frames and designer lines.  With the internet you can narrow your search immediately by brand or color or material, streamlining the selection process if you know your likes and dislikes. No more searching for frames on towering racks or drawers.  
Cons:
Some websites even have printouts to help you measure your PD at home in the mirror.  Be careful, because this measurement dictates where your prescription will be centered in your frame.  If you aren't looking through the center of your glasses, you will induce prism, which shifts and can possible distort your perception of image location (with much larger affects the higher your prescription is).
  • WELL, IT'S NOT THAT EASY.  In addition to the information on your glasses prescription, most websites require other measurements, such as your interpupillary distance (or PD).  The PD is a measurement that opticians take when you order glasses at any optical, and is not a part of your prescription.  Depending on  your doctor and their policies, they may or may not provide the PD as part of your exam.  
  • IT'S NOT INTERACTIVE.  While it's nice sometimes to do everything yourself, some of the jargon used in the world of glasses can be quite complicated if there is not someone around to explain things more thoroughly.  When you are asked to select whether you want anti-reflective coatings or CR 39 versus polycarbonate versus high index materials, will you know the best choice for you and your prescription?  
  • YOU AREN'T GETTING TO TRY ON THE FRAME.  I think this is one of the biggest cons to internet ordering.  Fitting a frame on your face is not just about how flattering it is to your face shape (though of course that is a plus!), but also about how the frame will work to provide clear vision and comfort.  A frame needs to be not too wide or  too narrow so that your eye falls in the natural center.  The nose-pieces need to be adjustable to correctly fit your bridge.  The temples need to be wide enough to not dig into your head, but not too wide as to cause the frame to fall off.  It is nearly impossible to be able to ascertain that a particular frame provides the right fit without first trying it on!  
  • THERE ARE NO QUALITY CONTROL STANDARDS IN PLACE TO VERIFY YOUR PRESCRIPTION.  That's right; many of these internet companies operate from offshore and even those that do not are not falling under regulatory jurisdiction at this time.  In the United States, the prescription in a pair of glasses must be within certain narrow tolerances to be acceptable (these are called ANSI standards).  Any power outside of this tolerance must be remade.  Lenses are also subject to safety testing to insure that the lenses aren't a shatter risk (this is called a drop ball test). For most lens materials there is a minimum acceptable thickness to meet these standards.  In a study recently reported in Optometry, out of 200 pairs of glasses ordered at various online providers, 44.8% were received with either prescription or minimum thickness falling outside of current federal standards.  That means nearly half of the ordered glasses were either the wrong power or not safe for protection against shattering!
  • PROGRESSIVES.  One thought: don't do it.  Progressive lenses (where the power gradually changes from distance to near without a line separating the two) need very precise measurements and adjustments to ensure that the wearer is getting appropriate vision at all distances.  The lenses must be cut so that the optical center of the lens has maximum distance power and is located where the eye is centered in the frame.  The add (or reading power) must be appropriately placed to allow ease of reading.  The width of the channel for reading is also very important to make sure there is enough reading room for the patient. How is it possible for an internet provider to make a quality pair of progressives without taking these measurements for themselves?  Good question.      
This is how a progressive lens is worked up to get proper alignment in an optical lab, as you can see  a few millimeters of measurement in one direction or another can cause major disruptions because of all of the factors at play.

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