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I recently got progressive lenses in my glasses and have been wondering how they achieve the (at least seemingly) continuous change in prescription? Is the glass formed to have a continually changing focal point or is it still made in segments (like bifocals or trifocals), just smaller ones that blend together more seamlessly?

Either way, how are they made to allow for this effect?

thesquaregroot
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  • Worth a read? http://www.wernerkoeppen.com/progressive-memories/the-competition-for-leadership-when-the-market-for-progressive-lenses-became-global/ and https://www.zeiss.co.uk/vision-care/en_gb/eye-care-professionals/optical-knowledge/optical-basics/lens-production/how-is-a-lens-produced-.html – Farcher Jan 21 '18 at 05:59

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Progressive lenses are made with a smoothly-contoured profile so the bottom-most zone of the lens has the most magnifying power and the zone nearest the top of the lens has the least. Superimposed on this "progressive" profile are the thickness variations used to correct for near- or far-sightedness, astigmatism, and other related defects.

niels nielsen
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