Eyeglasses Measurement Tips
This section is devoted to give tips to those measuring their own glasses to help improve their accuracy.
Tip 1: When you measure glasses be sure that you identify progressive glasses properly. If in doubt as to whether they are progressive, assume they ARE progressive and set the lensmeter accordingly. You then begin the measurement. If the add is .50 or lower, then they are not progressive and are instead single vision. Left and right adds should extremely rarely differ by more that .50. That is a big gotcha for some measurement people.
Tip 2: When you hold the glasses about 6 inches from the progressive identification grid, move the glasses from left to right and see if the lines seem to swirl into the nose area of the glasses. If they do, then they are likely progressive.
Tip 3: Another gotcha is sometimes with BiFocals the focal center for the distance prescription is actually behind the add area. You cannot make a measurement there so you must move the glasses right above the BiFocal segment, center them from left to right and force a reading by pushing the button at the top of the instrument.
Tip 4: Sometimes with progressive you may not get them to make a reading in the top area. If that happens, center the glasses in the top 1/3rd area and force a measurement. Now move down toward the nasal area to make a measurement of the add.
Tip 5: Allways make your first measurement for progressive centered in the top 1/3 of the glass. The second measurement for add should be as far down the glasses as you can go without going over the frame. Look at the below picture for a tip.
Tip 6: When you measure the add for a BiFocal pair of glasses, be sure that you press the lens against the measurement boot rather than measure the lens at an angle. Measurement at an angle will give an add higher than it should be.
Tip 7: When you measure glasses be sure that both sides of the glasses are firmly on and perpendicular to the platform. If you do not do this, your axis measurement will be wrong.
Tip 8: With the glasses on the platform, be sure that they are perpendicular to the measurement tunnel and platform and not at an angle. This can adversely affect the Sphere measurement.
Tip 9: We consider glasses which are readers are those which can ONLY be used a readers. This means that they are cut back at the top so that when you put them on your face, you easily see over them. If the glasses cover your vision at a distance, they should not be considered readers and should be placed in the inventory just like any other pair of glasses. Realize these glasses can not only be used as readers but can also be used for a person who is farsighted (can see well at a distance but not up close).