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Making My Own Glasses

eidel.io

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Re: Making My Own Glasses

#51

Post by criddell »

alfonsodev wrote: post #6
chrisseaton wrote: post #3

Earlier quoted context omitted.

> isn't it an objective way to measure it No it's subjective - I think that's the main point of the article.

I know, I though it might a very expensive but precise way to measure that with time or new tech could become afrodable.

I don't see why the entire process couldn't be automated. A machine could ask me "which is better A or B or are they the same?"

There are other parts of the exam that are more related to eye health, but I don't see why they vision prescription process and the eye exam have to be combined. How many people that don't wear glasses ever get their eyes examined?

Re: Making My Own Glasses

#52

Post by FPGAhacker »

coldtea wrote: post #31

> I have a few seconds to decide whether I see some letters better and this decision will decide which lenses I’ll have in my glasses for the next few years? Absurd! On the contrary, it seems totally logical. If the difference is so small that you can't assuredly decide between two options, either will do. > How can a trustworthy decision be made in this not-real-life scenario of staring at letters on a wall? I want…

> On the contrary, it seems totally logical. If the difference is so small that you can't assuredly decide between two options, either will do.

A slightly different way to interpret this would be to say that that particular axis of variation is at its limit, given the state of the other axes.

There are several axes, and they aren't perfectly orthogonal. Zeroing in on one can alter the best correction achievable on the other. Not all opticians will go back and iterate other axes, but I think it's a good idea. Lock X, find Y, recheck X given Y, etc.

Re: Making My Own Glasses

#54

Post by FPGAhacker »

alfonsodev wrote: post #2

> Optician: “Now with this lens, do you see better or worse?” > O: “Honestly, I have no clue. Maybe. Maybe not? The letters look similar but different.” [edit] Reprahsing to make it clearer: will it be possible in the future to measure objectively?

As others have said, yes, with limited accuracy. A big issue is the focus of your eyes is never static.

Imagine creating a lens system for a camera where you can't control for one element. That element is dynamic with a reasonable autofocus that suffers from time varying accuracy and range of performance.

We need dynamic correction. Glasses with auto/adjustable focus.

Re: Making My Own Glasses

#55

Post by vanattab »

amingilani wrote: post #43

This is amazing, however, I have the opposite problem: how do I measure for contact lenses? I've never been able to get a good fit for my contacts although my glasses have always worked well enough. The weird thing is that when I go to get contact lenses, the retailer orders them according to my glasses prescription, but subtracts seemingly arbitrary values from it to arrive at the contact lenses' values. I live in P…

Do you have a stigmatism? Contacts offten don't work well with people of stigmatism.

Re: Making My Own Glasses

#56

Post by cptskippy »

djhworld wrote: post #27
emptybits wrote: post #5

Fascinating hacker story in an unexpected domain. Thank you! A side note about "getting your numbers"... The author remarks, "she’s not happy to share the measurements with me as she fears I’ll run off and get my glasses made online". This will obviously vary by jurisdiction but what the author describes may be illegal in some places. e.g. where I live, there is a law since 2010 requiring opticians and optometrists "…

Not sure about legality but here in the UK you will find opticians will give you your prescription, but often exclude the pupil distance measurement (I think) which a lot of the online stores require. I think you can ask for it, but they will only give it begrudgingly.

In the US, the person who takes your pupil distance (PD) usually isn't the person who writes your prescription. One is a doctor and the other a technician.

When you go to an optician, the doctor takes you in the back and determines your prescription. Then you go out front to the showroom and pick out your frames. There is usually a technician out there who will take the PD measurement and combine it with the prescription, and frame and lens selection to make your order. The technician is also the person who fits you with the new glasses when they arrive.

Re: Making My Own Glasses

#57

Post by scoot »

Misleading title. He tested his own eyesight and ordered glasses online. He didn't make his own glasses.

Still an interesting read, just not what I expected from the title and lead.

Re: Making My Own Glasses

#58

Post by cptskippy »

LoSboccacc wrote: post #28
wonderwonder wrote: post #22

Earlier quoted context omitted.

This did strike me as strange. Imagine going to a doctor getting a blood test and being told your numbers are good or bad but the doctor refusing to give you the actual result. They are your results, you paid for them and are part of an overall need to understand your health.

> you paid for them most places that sell glasses do those for free tho. I agree they should be given out and they do in europe, or at least in the two states I lived, but being paid for is not the angle to come at it from

"Free" exams aren't free, the cost is included in the frames purchase. You can pay for an eye exam and walk out with a prescription, you just have to explain your intent.

Re: Making My Own Glasses

#59

Post by olieidel »

chooseaname wrote: post #10

> As a doctor I know some things about the human eye so I understand how to use those lenses. However, I have no clue about the magic ritual of the optician (“Do you see better with this lens?” - selects random lens and holds it in front of my eye). >Luckily, I didn’t have to. There's a specific reason why they do this and ask you to make a decision in an instant. It's called accommodation. Your eyes will quickly try…

Yes, I am a doctor. As far as I remember, I studied medicine and graduated.

As other comments point out, medicine is a very specialized field nowadays and I didn't specialize in any field (I got into coding healthcare software instead) - in Germany you study all disciplines at University (min. 6 years) and then specialize during something comparable to US residency in a hospital.

I understand the process of accommodation. This poses the risk of e.g. over-correcting short-sightedness if you're not aware of it because, with each lens of increasing strength, you accommodate and think "geez, everything just got sharper.. again!". I was aware of this and, as you can find in my article, actually ended up using very similar values for dioptries (the spheres) as the opticians. So either all of us totally forgot about accommodation or all of us were aware of it :)

My values mainly differed regarding to astigmatism, and accommodation doesn't play a significant role there.

I am also aware of the bone behind my ears, thanks for reminding me :)

While you do learn a lot of stuff in med school, learning how to bend those things of glasses which go behind your ears is not part of that. I suppose that's not a skill which can be taught well, anyway - it's more like craftsmanship, getting it right by having done it lots of times.

Re: Making My Own Glasses

#60

Post by jefftk »

> Do you remember the process in which an optician makes you wear a new pair of glasses and stares at you with this optician-look, takes the pair of glasses away from you again, goes to the back office and starts bending parts of it in a seemingly random manner, comes back, hands you the pair of glasses which now suddenly fit perfectly? Yeah, I attempted to do that with my new pair of glasses and noticed that I suck at it. I would bend it to look similar like the glasses from the optician only to realize that the back of my ears were hurting after a few hours of wear. Then I would bend them differently only to have them repeatedly slip forward on my nose warranting me to push them up every few minutes. After two weeks of bending, it still fits less well than the other pair. So I guess there are some subtleties of making glasses which are not easily replaceable through an online store.

I've done this with several pairs, and the main thing is you need to heat them to get the plastic into a temperature where it will hold a new bend. I've used a hair dryer for this, though you need to be careful not to over-heat them or the plastic will blister.

You can also go into a glasses shop and ask if they can adjust them, though when I tried this they wouldn't take my money and just did it for free, which I felt bad about.

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