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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
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.
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Amen. This seems like a good idea...but for the things I do that don't involve sitting in front of a computer or a book, it'd be a disaster. Both driving, and to an even greater extent flying, involve repeated, regular, rapid changes in focus distance from close to far, and especially while flying, my hands have better things to do than stay up at the bridge of my nose adjusting how well I see.
I've worn bifocals since I was 16 years old. (Focus flexibility problems don't always start in middle age.) These new glasses will not replace them, for me.
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Reading glasses: $2 at Northern Tool. Regular prescription glasses: $40 from internet (china). Total cost: $42.
VS.
Trufocals: $895.
Next topic!
This would be really cool for controlling tint in glasses though. Those transition lenses that do this automatically don't really work well. I would love a pair of glasses that allowed me to manually adjust the tint.
Notice how you now require several glasses for several ranges; one pair for close, one for far, and some progressive. You have to switch manually between those glasses. The invention now reduces the switch action to adjusting a slide.
No it doesn't. I'd still have to have progressives and a pair of magic-slider glasses. So instead of three pairs, I'd have two. Unless of course I can have glasses with 3 settings (progressive, fixed/near and fixed/far), in which case I'd gladly buy them.
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
The progressive lens I tried out at the optician's only gave clear focus over a five or ten degree horizontal field of view through most of its close-focus range. Anything left or right of center was astigmatically blurred. No way could I live with that, particularly in this day of "wider is better" displays.
I might consider a progressive lens that gave clear focus across the entire width of my FOV, but from what I've seen, that isn't happening.
That problem has been solved for decades, if not longer. Two polarized lenses, one of which can be rotated relative to the other, produce the effect you are looking for.
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...
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.
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There are real situations requiring instantaneous switching among or maybe even simultaneous use of multiple focus distances. A good example is playing an instrument in a band or orchestra. It's important to be able to see both the conductor (at a distance) and the music (arms length), more or less at the same time. If glasses are focused only at arms length, attempting to see the conductor is pretty uncomfortable. This may be useful for some, but not for me.