Eyeglasses Frame Measurements Are Very Valuable!

by admin on 05/05/2009

Not every single customer or patient knows why they have to sit through a bunch of measurements when they come into a doctor’s office or retail eyeglasses chain in order to get a pair of eyeglasses. Many of the first time customers figure that all one needs is the eyeglass prescription and it’s a go. Well, it isn’t that simple. In fact, quite the opposite of simple – very complex.


In order to make eyeglasses specific to any and all individual’s needs, the Optician must measure for the eyeglasses accordingly. The laboratory staff making the glasses need to also ensure that these measurements are correct so that they can promptly return a near as perfect as they can get product to the customer.

Measurements that are erroneous cause horrible things such as unwanted, unprescribed prismatic effects which could cause a sloping or tilting sensation as the customer wears finished eyeglass product, inability to read things properly if the bifocal set incorrectly, and even additional distortion from improper inset or outset in progressives. The problems that can arise from improperly measuring for eyeglasses are many,therefore, proper care must be taken when do so.

So…how do you measure properly to fit a patient for eyeglasses? In summary, there are some basic measurements that any Optician needs to constantly ensure are correct. Though there are many more, these are an absolute necessity at all times.

A – (across) This is the measurement that is from side to side of the eyewire. Horizontal measurement. This is important to stray away from unwanted prism as well as the “pulling” sensation caused by unmatched optical centers eyewear to patient.

B – This is the up and down measurement of the eyewire. Vertical measurement. This is important to prevent unwanted vertical prismatic effects as well as improper bifocal settings.

DBL – Distance between the lenses. This measurement is taken at the nasal or at the bridge of the frame between the eyewires. A wrong DBL throws all measurements off in the manufacture of eyewear causing prism and more.

opticianworld-simple-frame-diagram-copy1

FPD – Frame Pupillary distance. This is the measurement that is equal to the A + DBL measurements. The sum of the FPD must equal A+DBL when measured or the finished product may come out totally wrong.

Remember, all eyewear frame measurements are in millimeter, therefore, this proves that the slightest bit of error can cause a mountain of trouble.

Oh yes, and don’t forget the PD or the interpupillary distance measurement.  This measurement isn’t on the frame however.  It is actually on the patient.  This measurement can make or break the finished eyewear product as this measures the distance between the patient’s pupils with a PD stick or Pupillometer.  If this is wrong, well toss the pair of glasses as depending on how off the measurement, any thing from prism to simply can’t see is going to be the problem.

HINT HINT*** On the frame itself, check the temple and the nasal bridge.  Normally, the measurements are engraved in the temple and/or nasal bridge of the frame!  Always double check yourself and the frame.

You should be able to find the temple length, A measurement and DBL measurement in these two places on the frame.  This gives you a simple short cut to double checking your own measurements.

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