Codes imprinted on glasses lenses?

I recently got a new pair of glasses (progressive bifocals, so yes I’m over 40), and I was closely examining the lenses while wearing a different pair of magnifying glasses. The new glasses weren’t working so well, so I thought I’d look for flaws in the lenses.

What I found instead were some letters and numbers imprinted on the lenses. On each lens I can clearly read the letters “CDX” underneath a circle and the numbers “200” also underneath a circle. The light has to hit the lens in just the right way to see the imprinting, but it’s definitely there. Usually I would not be able to see something so small up close (being farsighted), but I was wearing a different pair of magnifying type glasses at the time.

Is the imprinting supposed to be there? What does it mean? Could it be affecting my vision?

Thanks in advance.

Yes, those markings are supposed to be there. The numbers are your add power, 2.00 in your case. The letters are to identify the brand. The circles are to allow an optician to recreate the fitting crosses, which is sometimes necessary if someone is having trouble with the lenses.

Progressives are tricky to fit properly. They come with markings on the lenses, big circles with a cross under them at the top and smaller circles at the bottom. They are used by the optician to line the lenses up in front of your eyes, the crosses should be directly in front of your pupils when looking straight forward. The higher the add power, the more noticeable it will be if they’re not centered correctly. Unfortunately, only a handful of states have any kind of licensing for opticians, so it’s all too common for unqualified people to be fitting glasses.

If there is something wrong with them, it’s most likely either they weren’t adjusted correctly, or they weren’t measured correctly in the first place.

I had this on my last pair of glasses - the marks were near the centre of the lenses - I wore them fir a few days, continually feeling like there was a speck of dirt on them, or something was in my eye.

I eventually examined them (wearing my old pair and using a hand lens) and there were little circles with letters and numbers.

I took them back, as it was unbearable wearing them; they tried to argue that there would be no way I would ever notice them. They caved when I said “so if I’d never notice them, how am.I standing here telling you they’re a problem?”

Marks in the center are definitely a flaw. The engravings, which are hard to see without magnification, are on either side of the lens and below eye level when looking straight ahead. In 15 years of being an optician, I only had one person who could see them while wearing them. In that case, the engravings were too deep – the person was actually seeing reflections bouncing off the engravings – and the lab replaced them without question.