In most places, they're required to give you the prescription but they've always "forgotten" the IPD, IME. It's not really a problem because it doesn't change. Get it once and you're good. Zenni will also send a gauge (free) so that you can measure it yourself.
Same. Sunglasses, too. Insurance didn't Zeiss lenses or Tag Heuer frames, though (fixed $200ish of the ~$600).
That's just a matter of the brain "learning" it's new eyes. That's also the problem with having several pairs of glasses. It never gets to be natural.
On Tue, 20 May 2014 14:51:49 -0500 amdx wrote in Message id: :
If you have a wheel mouse, you can do the same thing by holding down the control button and using the wheel to zoom in and out. I use this feature all the time.
Since so many have problems with loss of vision as we age - I will present why this happens biochemically, and how to prevent it, even reverse it once its started. The villain (one villain) is glycation of proteins in the body via blood sugars. That's a major part of the glycation-oxidation-deterioration process of aging.
Here is a discussion:
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The glycation process puts a fuzzy coating of sugar on proteins. At the atomic scale, this would be like obliterating key features of the protein, like throwing a thick woolly blanket over a distinctive piece of furniture and softening its shape. (Besides this cloaking, we have cross-linking.) This cloaking has several consequences.
In brief, your body's SNR gets much lower. To function as a complex bag of molecules, your body depends on recognition of specific surfaces by hormones, messengers (like excess glucose in blood), enzyme systems (like the energy system in mitochondria), and the immune system antibody templates. All of these biological addresses depend on distinctive features exposed by the proteins (mostly hydrophobic), and cloaked by blood sugar reactions. (mostly hydrophilic) It is like injecting noise into a system dependent on address recognition.
As the SNR deteriorates, the critical body systems deteriorate. The immune system can't recognize rogue cancer cells, and you get cancer. The immune can't tell who you are anymore, and you get various forms of arthritis. The electron transport enzymes in the mitochondria can't hand-shake with each other to create ATP, so your energy goes way down, like the voltage in a house goes to
The situation has a way of becoming run-away, or exponential. Not controlled by a high SNR address bus anymore, the insulin system allows your blood sugar to rise more, causing runaway amplification of noise. Blinded immune police fire randomly at the body's cells. Rogue enzymes attack the structure of the body and dump free radicals (a noise partner of energy reactions) into the blood stream. Your retina/lens gets glycated, and your vision deteriorates. You are doing what any piece of biological tissue does without functioning protective systems: spoiling and dying.
The reference above recommends benfotiamine as a natural OTC supplement to stop the glycation blow-up described above. I myself am constantly learning this area of systemic medicine, and earning about the benfotiamine, a low cost supplement which stops glycation, is a welcome piece of knowing. It also shows signs of reversing glycation, as measured signs go down. Will using this B-vitamin derivative drop 20 years off your age in various ways? I'd guess yes, but the turnover time of proteins means it may take a year to happen, as SNR gradually comes back.
And of course, the usual disclaimer to see your doctor about any medical matters, but you are the one who is in charge of your health, not your doctor. Blood sugar control has a lot more than is presented here, but the benfotiamine is a good way to start. I myself learn a number of things about preventive medicine every day. I don't take benfotiamine, but I will now. I also wanted to apply the electronics narrative to systemic medicine - concepts like noise, SNR, entropy, signally systems, pattern recognition, feedback, addressing - all seem the best systems way to describe what is going on in aging and disease.
I asked and it's intentional and part of some kind of turf war. Measuring the IPD is suppose to be the job of the dispensing optician (the shop that sells you the glasses). I've gone to the glasses counter at Costco, and had them do the measuring for me. The numbers were off and I had to mangle the wire frame to compensate. Grrr...
My method is to tape a steel rule to my forehead and take digital photographs. I then draw parallel lines on the computer screen or print to extract the distance. It usually takes 3 photos to deal with the parallax. One with my eyes at infinity for distance. One at the working distance of my monitor. Another close up for the small stuff. Then, I save the prescriptions and IPD on the Zenni site: You can also see how the glasses will look.
Note that when ordering bifocals, Zenni only wants the IPD for distance viewing. They allegedly tweak the IPD slightly closer for the higher powered (close up) part of the lens. However, when ordering single vision lenses, such as reading glasses, you have to use the IPD at the reading distance.
Drivel: About a year ago, my body mechanic changed several medications and dosages. Over the year, my previously astigmatic vision seems to be slowly fixing itself. I've been driving around without glasses for about a week and no eyestrain. The dashboard still looks like a big blurr without glasses, but the distance vision seems to be just fine. I'll let it go for another month and then get a new eye exam. Weird(tm).
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Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Or maybe 60 cents to make. Zenni will sell you prescription glasses starting around $8.
I don't think I have ever sent Zenni a prescription. Their web site seems to have a mild suggestion that I could do so.
I just make up my own numbers and fill out the forms. I've done glasses for my wife, too, and never sent in her prescription. Zenni has zero incentive to police this stuff.
The whole eyeglass thing in the US is a monster ripoff. Places charge $300, or $500, for glasses, and I bet they have them made in China. It's like oscilloscopes-- may as well just order the Chinese ones and save a bundle.
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John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
In California, optometrists refuse to tell you your IPD.
I use a mirror, up close: stare straight into it with one eye and make a mark on the mirror dead-center on that eye's reflection. Repeat for other eye. Measure.
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John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
An even bigger ripoff* is the price of hearing aids! You can buy a very high end computer for the price of hearing aids and still have a bundle left over. Mikek
*and then there's Obamacare.
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Yes I agree. I think hearing aid costs are coming down though. Makers say they have to charge 7000$ to recover R&D costs, but R&D was paid for by the government originally anyway. I see H.A. as like transistor radios - when economies of scale and competition kick in, costs plummet. It's just beach sand, right? :) jb
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As I understand it, the IPD is not a formal part of the prescription under California state law. The optometrist is thus not obligated to measure it as part of the eye exam, and isn't obligated to disclose it even if they do measure it. If there's a "captive" eyeglasses shop associated with the optometrist's office, they aren't obligated to provide it (since it's not actually part of the prescription).
My own optometrist didn't do the measurement when I had my most recent eye exam, and it wasn't on the printed copy of the prescription she gave me. She said that the people doing the actual fitting-of- the-glasses (at their "captive" shop downstairs) would do the measurement and that I should ask them to note it on the prescription. They did, I did, and they did, and now I've got that information recorded for future use.
That's the distance at infinity, simple geometry can be used to calculate the IPD for closer distances, it's a bit closer (2-3mm?) for computer glasses.
If I try to adjust the focus on my distance glasses for computer use, by parking them near the end of my (not terribly long) schnozz, the IPD distance is wrong .. even more wrong because of the increased lens spacing.. (plus the defects start show up more) so .. headaches.
We passed that point a long time ago, but like many "medical" devices hearing aids are sold without the benefit of competitive pricing because of the marketing techniques.
There are even special DSP chips intended for hearing aids. Low cost (
Perhaps because there's no place on the form to write the information?
I also asked why she hands the patient and unreadable hand written prescription in non-reproducible blue ink, but types the numbers into the computah. Couldn't the computah produce something that's readable? No answer.
I just tried it. I made several independent measurements spaced about
30 mins apart. I had to be very close to the mirror, which is a problem for me as I can't really focus on the reflection. The measurements varied over a 3 mm range, some of which was the 1 mm diameter of the felt tip pen. In my opinion, this method is neither accurate nor repeatable. It might work for infinity (distance) viewing, but I couldn't figure out how to obtain the IPD for computer and reading glasses, which require that I stare at something at a distance of about 40 to 60 cm).
A -3 mm fudge factor might work for some people. For my eyes with astigmatism, having the lenses 1-2 mm off axis will cause problems. Here's my numbers from a series of measurements over the last 10 years. Looks like a -5 or -6 mm fudge factor. Driving 61.1 mm Computer 56.0 mm Reading 55.2 mm Closework 55.0 mm
Maybe just buy a pupilometer:
Good idea. I have a few pairs that I've destroyed that might be fun to play with. Mostly I want to see if a 1-2 mm IPD error really does have an effect.
Also, for only $900, one can get fluid filled adjustable glasses: with the added bonus of making the wearer look like a nerd|geek|retro. If that's not sufficiently "techno", go for the real thing: or the ultimate in vision enhancement: or join the Borg and get a free cool looking half-eyeglass accessory: Resistance may be futile, but persistence usually works.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
I'm down to about 7" for middle of focus range-- it's getting a bit close for soldering.
Best regards, Spehro Pefhany
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I bought one of the digital Chinese ones for something like $40. Not worth anything. Maybe the more expensive ones work better.
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Best regards, Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
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