Progressive lenses

Thursday 8 May 2003

Because of my advanced age, I am afflicted with presbyopia. To correct the problem, I have a new pair of glasses with progressive lenses. These are commonly known as no-line bifocals, but really, they are a different beast than the classic bifocal lens, because there is a gradual progression between the two ranges of correction.

This also makes them difficult to get used to. It seems like everything I look at is out of focus until I move my head properly to be able to see it. I'm told I will get used to it. We'll see (no pun intended).

But they got me interested to learn more about lenses. The geometry at work here is extremely complicated. And how exactly are they made? After all, the curves are complex and subtle, and the lenses that result will be used in very sensitive-to-error situations (that is, I'll be looking through them for a few years). How Stuff Works comes through with a good description of how standard lenses are made.

Comments

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joat 10:17 PM on 9 May 2003

I don't know which is worse: having to get used to progressive or bifocal lens OR the fact that you sister sends a birthday card with a really cute blonde on the front and the inside saying, "Just think, you're old enough to be her grandfather."

[gravatar]
ralph 10:07 PM on 17 Oct 2008

I just got progressive glasses. Reading is a nightmare. When I have to read anything wider than one column, I have to turn my head and look directly at the words. My computer oscillates as I move my head. Same thing with driving - I cant see the lisence plate in the next lane unless I look directly at it. My up close vision, before it becomes blurry is about 4" on either side. Is this normal? How long will it last?

[gravatar]
Ned Batchelder 5:53 AM on 18 Oct 2008

It is very difficult to get used to at first. After a few weeks, it seems much more natural. My optometrist said, "You have to point your nose at what you're looking at", which I still find true after all these years. You can't look askew at things, because you'll be using the "wrong" part of the lens. So you end up moving your head to look at things more than you are used to.

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