Adjustable-Focus Glasses Can Replace Bifocals

Hugh Pickens writes "The NY Times reports that inventor Stephen Kurtin has developed glasses with a mechanically adjustable focus that he believes can free nearly two billion people around the world from bifocals, trifocals and progressive lenses. Kurtin has spent almost 20 years on his quest to create a better pair of spectacles for people who suffer from presbyopia — the condition that affects almost everyone over the age of 40 as they progressively lose the ability to focus on close objects. The glasses have a tiny adjustable slider on the bridge of the frame that makes it possible to focus alternately on the page of a book, a computer screen, or a mountain range in the distance. 'For more than 140 years, adjustable focus has been recognized as the Holy Grail for presbyopes,' says Kurtin. 'It's a blazingly difficult problem.' Each 'lens' is actually a set of two lenses, one flexible and one firm. The flexible lens (near the eye) has a transparent, distensible membrane attached to a clear rigid surface. The pocket between them holds a small quantity of crystal-clear fluid. As you move the slider on the bridge, it pushes the fluid and alters the shape of the flexible lens."

Comments

How is that an improvement?

[Rosco P. Coltrane]

The glasses have a tiny adjustable slider on the bridge of the frame that makes it possible to focus alternately on the page of a book, a computer screen, or a mountain range in the distance

Whowever designed this has obviously never worn progressive lenses. In real, ordinary life, you don't "decide" to focus on something for a minute and adjust the slider accordingly, you adjust your focal point *all the time*, unconsciously. What progressive lenses do is allow your neck muscle to "emulate" what your eye muscles would normally do if you weren't an old fart.

I just don't see myself (pun intended) spending the day with a finger on the rim of my glasses to do the same. If I want to be comfortable for an extended period of time in front of the computer, or to drive, I put on my near or far glasses. For the rest of the time (90% of my day), I put on the progressive glasses. Perhaps the adjustable lenses would allow me to have one pair of comfy glasses instead of two, but I ain't giving up my progressives. At any rate, my reading glasses are on the table, and my driving glasses are in the car, so it's not really a problem in the first place.

(On a side note, I've just realized I'm talking about my presbyopia on Slashdot, and the dreaded word "middle-aged" comes to my mind.)

Re:How is that an improvement?

[MartinSchou]

What you're failing to realize is that this is the first step towards glasses that adjust their focus automatically.

Right now it's done manually. Just like we used to manually card wool.

Given time, the electronics needed to measure where you're looking, the distance to it and adjusting the focus will be built in to the glasses.

tiny slider

[MagicM]

The glasses have a tiny adjustable slider on the bridge of the frame

Good thing the over-40 crowd is well-known for their dexterity and ability to accurately manipulate tiny adjustable sliders.