Slashdot Mirror
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."
...how do you clean them?
I've had glasses for ages now. I clean them every day. My rigid plastic lenses eventually develop small scratches no matter how careful you are.
So how will these lenses with movin parts hold up when cleaned for every day for N years?
The FAQ claims:
I'm not impressed unless it's been proven over time...
.: Max Romantschuk
But the price, the price...
My presbyopia is such that I just do without spectacles for close work, and don monofocals for driving, etc. I have bifocals, but they irritate me to no end. If adaptive focus spectacles are reasonably-priced (no more than double the cost of good coated bifocals), then I'll be first in line.
Those who can make you believe absurdities can make you commit atrocities. - Voltaire
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.)
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
Water-based eyeglasses
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
They're three years too late for me; I had a CrystaLens implanted in one eye in 2006. It is an adjustable focus lens that replaces the eye's natural lens, and it uses the eye's focusing muscles to focus.
Its drawbacks are first, you have to have surgery, and second, it's pretty expensive. It's affordable if you have cataracts, where insurance will pay most of the costs and even then the out of pocket expense to cover the difference in price between an old fashioned InterOptical Lens (IOL) and the new one.
Your eye actually has two lenses; the cornea and the crystalline lens. The latter is what focuses, until you reach your forties when it starts becoming stiff, too stiff for the eye's muscle to move.
These new reading glasses would be a boon to anyone with the old fashioned IOL, anyone who is afraid of letting a doctor stick needles in their eyeball, and anyone without about $6,000 to get one eye fixed. I'll bet they're expensive (haven't yet RTFA) but I'm sure they're cheaper than surgery, and like all new technologies, the price will come down in time. In twenty years you'll be able to get them for ten bucks in today's money, I'd be willing to bet.
Free Martian Whores!
I've been wearing glasses for over 35 years since kindergarten, and about two years ago, I got progressive lenses. Sure, they were a bit strange at first, but within a day, I just "got it" and I think they're great! By simply doing "micro adjustments", I can get pretty much anything into focus very quickly.
I really don't see what the big deal is. Can someone please explain why progressive lenses are so despised?
My mom always said, "Jim, you're 1 in a million." Given the current population, there are 7000 of me. God help us all!
Reading glasses: $2 at Northern Tool. Regular prescription glasses: $40 from internet (china). Total cost: $42.
VS.
Trufocals: $895.
Next topic!
I really, really want adjustable-focus lenses. But I don't want heavy lenses, and I don't want large, round lenses.
I'm hoping these folks, linked in TFA, can deliver. Electronic focus sounds a lot more appealing and reliable.
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.
This really sounds like a solution in search of a problem. Bifocals and trifocals work, and have no moving parts.
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Just get a bigger monitor.
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You're only semi-conscious; they drug you into what they call "twilight sleep". They use anesthetic eyedrops to numb the eye and they put an IV in your arm with the "twilight sleep" anesthesia. They tie your arms to the gurney "so you won't try to help the doctor". The only unpleasant part is when the needle actually goes into your eye, but it's not painful, only shocking and wierd. They have some sort of frame over your face that lets them see inside your eye with a microscope (they dose your eye with dialation drops as well as anesthetic) and holds your eyelid open.
You don't see the needle coming towards your eye. I journaled about it; the link is in the comment you responded to. The needle goes through the white of the eye and they shoot ultrasound through it to turn the lens to mush, suck the mush out and insert the prosthetic lens. It sounds bad, but it isn't. The best part is I wore thick glasses all my life, I was severly myopic. The CrytaLens cures myopia (nearsightedness), presbyopia (farsightedness), astigmatism, and cataracts. The eye I have the implant in is now better than 20/20 at all distances, but the surgeon said mine worked out better than most.
Now, a vitrectomy, that's a nightmare. I wouldn't wish one on anybody, but it sure beats the certainty of absolute blindness. BTW, one slashotter asked me to warn people before I link the vitrectomy journal, it really freaked him out. There's a link to the wikipedia article about victrectomy in that journal, and there's a picture in the wikipedia article that is NOT for the faint of heart. Pray you never have a detached retina!
Free Martian Whores!
People get that way because the lenses in their eyes stiffen with age and soon the muscles int he eyes can't adjust them properly. People who have had certain type of cataract surgery where they replace the lens inside of the eye usually regain most all of their focusing ability.
Tsukasa: All I really want, is to be left alone...
Yes, the lens stiffens with age. (There was a competing theory that it grows with age, and that focus problems arise because the focus mechanism doesn't have enough range of motion to adapt, but that apparently hasn't been borne out by further studies.
No, in general, lens replacement does NOT give you back focusing ability. There's one type of lens (Crystalens, referenced upthread) that restores accommodation for some recipients, but results vary widely, and regular replacement lenses don't accommodate at all.
I wonder how these will respond when temperatures may vary significantly. Will I need to adjust them going from an air-conditioned office out into a sweltering summer day? Similarly going from a heated house into a Minnesota winter? What about possible freezing? I take my glasses with me when I camp and some nights the temperatures are below freezing both inside and outside of my tent.
I guess I'll watch for this to hit the market, but am simply glad I don't need them yet.
I use irony whenever I can, but my shirts are still wrinkled...