The Marks on Progressive Glasses (Lenses)
Lenses · 2021-12-12
The Marks on Progressive Glasses (Lenses)

We may find marks on the progressive glasses purchased, and some even think that are the defects of the lenses.  Theses marks appears as circles, letters and numbers as showing in the picture below.

marks.jpg


So, what are these marks?  Do you have to feel embarrassed to wear a pair of glasses with marks?  Of course not.  These are the marks left on the surface of the lenses during the processing.  It is a standard industrial practice to engrave or etch these markings to align exactly where the point in the lens is that starts changing from your distance Rx to your reading Rx.  These engravings are etched into the front surface of the lens at about the depth of 0.05 mm. In comparison, the average thickness of human hair is about 0.06-0.08 mm.   


On each lens, there will be two of those circles (or other identifying mark depending on the manufacturer of the lens, but they are always the same in each lens). The 175 is the reading power or ADD as prescribe on your prescription.

The marks are always in the blending regions, the peripheral regions of the lens containing non-prescribed power and provide only minimal visual utility.  Hence, these marks will not affect your vision.  Even if you manage to look directly through the marks while wearing them, the power you are looking through won't be very helpful anyway. Consequently, your eyes will naturally keep away from that area.

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Reference reading:

1. https://www.visionvalet.com/blog/pal-markings-to-noticeable-61

2. https://progressive-glasses.com/what-are-the-markings-on-my-progressive-lenses/


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