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Comment by johndoe491 | Hacker News Reader

I learned to cross my eyes way back in the mid nineties during the "3d poster" craze (and man those posters were amazing, zo SO much better than the crap images found on the web). I remember they sold them in the tube in London, in gorgeous color and the depth was fantastic.

But anyway... do we know that convergence actually helps vision? How so? What is backing this up?

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We know that poor convergence affects near vision. Presbyopia also affects near vision. Are convergence and presbyopia related? Should you ask the person trying to sell you a pair of expensive progressive lenses?

http://www.convergenceinsufficiency.org/

https://en.wikipedia.org/wiki/Amblyopia

http://www.strabismus.org/

The exercises are easy to try and have almost immediate (temporary) positive effect. They work for some people. There isn't an economic incentive to fund studies to determine why they don't work in others, since this could hurt various revenue streams. Standard big pharma vs. wellness dilemma. However, video game software subscriptions for vision therapy may change incentives.

http://www.strabismusworld.com/

https://www.seevividly.com/

And also, I'd like to point your attention to Aniseikonia, an EXTREMELY underdiagnosed issue:

http://www.opticaldiagnostics.com/info/aniseikonia.html

Neither clinical neuro-ophthalmology, nor orthoptists, nor optometricians, nor opticians, commonly have the equipment to test this, let alone know about it. (I had to literally have a lens kit dusted off in my case. One that nobody besides one entire person in the city knew about besides me.)

And the fact that one must consider the current distance and measuring equipment used for vision tests insufficient:

http://www.tedmontgomery.com/the_eye/acuity.html

To quote:

"Traditionally, optical infinity has been accepted to be 20 feet or, approximately, 6 meters. However, at this distance, there is an accommodative demand on the eye of about 1/6 D (one-sixth of a diopter). This amount of accommodative demand can be significant for some people. For very discriminating observers (such as myself), an accommodative fluctuation during an eye examination of more than 1/8 D can result in a variable endpoint in measuring a person’s refractive error (resulting in an imprecise lens prescription), and 1/6 D is even greater than 1/8 D.

As a result, it is recommended that the viewing distance (d) in an examination room should be great enough to create no more than a 1/8 D accommodative demand on any patient’s eyes. I maintain, then, that optical infinity, for purposes of examining the refractive error of the human eye, is at least 8 meters or 26¼ feet, rather than merely 6 meters or 20 feet."

This combines with the fact that that the human eye experiences "accommodative microfluctuations" which have a range of about 0,5 diopters (aka ±0,25 diopter), and it does so even at true optical infinity.

This then makes any assessment done without cycloplegia problematic, but assessment under cycloplegia also has its issues:

There exists a dissertation from a German Technical University (Well, "Fachhochschule", look the term up if you have an obsession with detail like I do) that beyond the shadow of a doubt proves that Schack-Hartmann sensor based Wavefront aberrometers can and will do better than humans when measuring the ideal prescription for a human eye. However, this dissertation, even as good as it was (they had a huge sample size and accounted for damn near everything), has several limitations and also points several problems out, and in addition to these, I'll add a few ones I've observed myself and that one can find in the literature (this is from memory and reading a lot of the literature, but keep in mind I can't find the original paper [in German] anymore, and some of this comes from other papers):

1. The default setting of most wavefront aberrometers defaults to 3 eye measurement cycles per eye measurement. However, the study found quite clearly that at this setting, a wavefront aberrometers will very often do worse than an experienced human optometrist or orthoptist, even if they do account for the distance problem I described above, which nearly all of them don't. A 5 measurement cycles however elevate the wavefront

2. Most wavefront aberrometers lack the capability to do a proper measurement of a fully dilated pupil as they expect a maximum pupil dilation of about 5mm, which is ridiculously tiny

3. Wavefront aberrometers cannot compensate for deeply (or at all) cramped cilliary muscles, an extremely common issue

4a. To get a dilated pupil, one must apply a mydriasic (i.e. pupil dilating) agent such as cyclopentolate.

4b. To get a relaxed cilliary muscle, one must apply a cycloplegic (i.e. cilliary mucscle paralyzing) agent such as cyclopentolate.

5. Most wavefront aberrometer measurements occur in the office of an optician, who legally may not dispense cycloplegic & mydriasic eye drops (such as cyclopentolate).

6. This is a good thing, because cyclopentolate is an muscarinic antagonist. Normally relatively harmless, when given to people with various atypical neurological features such as for example some of (but not all of) those exhibited by some of (but not all of those) those diagnosed with schizophrenia, it can lead to acute psychosis.

7. The above seems doubly unfortunate because schizophrenia seems to have an - extremely little researched - link to the previously mentioned Aniseikonia: http://www.schizo-binoc.de/ [Personally, I think some of the hypotheses on the neurological mechanisms of this link as offered by Hildegard Korn seem whack, but if you look at purely her quite empirical - albeit possibly anecdotal - data, you'll see that the pattern she describes along with the formal errors in commonly used diagnostical procedures she outlines quite flawlessly do add up to something and could probably get easily explained, in terms of neurological mechanisms behind the observed biophysics, by a more respectable theory on the neurological mechanisms behind it.)

And then there's the whole patent lockdown between all the big glasses manufacturers, but I cba to continue typing this out.

I truly despise the optical and ophthalmological industry. They still haven't heard Sue Barry's message although she's shouting it with all the force she can muster.

One note is that opticianry and optometry are not separated in Germany. While this may lead to conflict of interest, it can also lead to a better eye exam. We can now manufacture lenses to 0.01D but still perform exams in 0.25D increments. Everyone should have their eyes examined by two independent doctors, preferably in diverse cities, just to see the range of subjectivity involved in each prescription.

Why can't SeeVividly vision therapy be made available directly to consumers? Is the reason technical or business, to avoid conflict with eye doctors?

The computer industry may be on a collision course with the optical industry, due to augmented reality and smart glasses. We all know what happened when pocket computers collided with mobile telecom/carriers. The illusions provided by AR depend upon the brain's visual cortex and neuro-plasticity. Smart glasses may use 3D printing / nanoscale manufacturing to create transparent "lenses"/"displays" which embed cameras and microphones.

Thank you for the Sue Barry pointer: http://www.stereosue.com/

>While this may lead to conflict of interest, it can also lead to a better eye exam.

I have very good familiarity with the situation in Germany. It's barely any better there due to the same limitations I've already outlined. Granted, you find more opticians with 1/8 diopter trial frame lenses there, but it's still a rarity and opticians lack orthoptic training, something NOT supplementable by normal optometric training (which already goes beyond optician training), even if the IVBS would like you to think otherwise.

>Why can't SeeVividly vision therapy be made available directly to consumers? Is the reason technical or business, to avoid conflict with eye doctors?

Liability.

I've recently developed intermittent vertical diplopia (double vision) - it will happen out of the blue and last for a few minutes (closing eyes and relaxing seems to clear it up). I've been trying to wear my reading glasses more often and also when on the computer and it seems to have largely cleared up, but it still happens now and then. Do you think it's safe to consider it problem solved or should I be looking into it more? Went for an eye exam and she said everything was fine.

Causes of diplopia range from the innocuous to the serious, I would investigate a bit further and rule out the easy stuff (diabetes/thyroid) and stay alert for other possibly related symptoms.

There are lots of possible causes of double vision, including neurological. If it's still happening you really should see a doctor (a good GP.)

Do you have bouts of doubled vision with only one eye open? If so, that is likely astigmatism which can be temporary.

No, closing either eye clears it up thankfully.

Actually, lack of stereo synchronization can be more serious than astigmatism which is usually an optically correctable condition.

Sorry for the late response. I overlooked this. Go see a doctor. Never fuck around with double vision. Especially not with vertical one. And make sure to AVOID horizontal prisms. They never work as a solution except in cases of actual muscle /paralysis/, i.e. via the nerve, and not just muscle "weakness". The muscle weakness theory of strabismus and diplopia seems akin to a load of hogwash, as it fails to pass even the simplest human bioenergetics(and I mean the scientific field that deals with caloric distribution & thermoregulation, not the - unfortunately more well known - hurdur pseudoscience term.) litmus tests:

If given a sufficient nutrient supply and an issue stemming from muscle strength, then exercise alone must suffice to grow the muscle. If the issue stems from muscle length, then exercises alone must have the capability to lead to elongative growth. However, this requires an incentive to LOOK IN THE RIGHT WAY instead of supressing the image. As a theory, it fundamentally confuses cause with effect. Yes of course the muscles become unbalanced - as a CONSEQUENCE of the neurologically originated suppressive (amblyopiatic[sic]) action of averting the gaze of one eye to ensure the brain doesn't have to keep on encountering statistical near misses that waste neurological resources.

If our muscles had some kind of "critical period", then people who didn't hit the gym as children couldn't ever gain muscles in a gym as adults. A clearly absurd notion, thus, via reductio ad absurdum, QED.

I recently got a few pairs of glasses from the most common optical retailer with their best lenses (Ray Ban Rox Plus in sunglasses and BlueIQ in the regular ones). I have a light single vision prescription (about -1.5 sphere and -1 cyl in each eye) but still, I find these are not very good lenses -- I see plenty of chromatic aberration on the sides (I guess they're both made from polycarbonate where I'm more used to getting CR39 plastic) and they both appear to have other abberrations in the plastic that I can see when I pass different parts of the lens in front of my eye.

As a photographer, I'm really interested in having excellent optics in front of my eyes, but I don't know how to achieve it. I agree with the comments above -- it's sucky that you have to make full .25 incremental jumps, and that the axis for astigmatism is still determined by me having to say "1" looks better than "2" and "3" looks better than "4", all done with antiquated equipment manually operated when it should all be readable right off the retina.

Couple this with high pressure salesmanship and no transparency at all about the lenses and it is obvious why it's so hard for the consumer to get this right.

Yesterday I learned that Sam's Club offers Nikon, Zeiss and Seiko lenses. Some of my favorite glasses I got in Japan for $80 and they included standard Seikos with UV protection and great AR coating.

Try a digitally surfaced Zeiss single vision lens in Trivex. It can be made in 0.01D increments. Visit a local university for your eye exam, they're probably not trying to sell you lenses. Seiko has good products but were bought by Hoya and have been going through many internal changes.

https://www.personalizedvision.com/zeisssinglevisionhd

Sorry for the late reply. Chromatic aberrations primarily originate from glasses with a low Abbe number, which ROUGHLY (_but not strictly!_ RARE [and expensive] exceptions exist!) correlates with glasses with a high refractive index. Get glasses with a high Abbe number (which you'll likely find in glasses with a low refractive index) and the chromatic ab(b)errations will disappear. The price you have to pay: They'll end up heavier. But only slightly, thanks to modern organic glass polymers whose surface we, via surface treatment, can make harder than mineralic glass nowadays. A capability that has only appeared in the last few years.

As for the rest, the advice given in the other reply to your comment seems sound.

> There isn't an economic incentive to fund studies to determine why they don't work in others, since this could hurt various revenue streams.

I could be incredibly naive, but it sounds like a public health issue. Depending on how widespread it is, I can see any country organizing a study or pilot program. The country wouldn't have economic competition from big pharma and would see having a healthy and skilled population as an economic advantage.

The global numbers for myopia are rising in children, https://www.brienholdenvision.org/myopia-prevalence.html, "The hot spots of myopia right now are in East Asia where countries such as South Korea, Taiwan, Singapore, China and Japan have a prevalence of myopia of 80 to 90% but even the USA has reported a staggering prevalence of 42%, almost doubling in three decades."

A few behavioral optometrists have spoken up or published books on these topics, but they are a tiny minority, e.g. https://vision-therapy-pa.com

I can't find the link but I seem to remember a study found that exposure to sunlight (at least the level found on an overcast day) was required for ~4 hours per day to prevent myopia.

This link had been suspected previously but they found a mechanism of action. The eyeball itself would release regulatory chemicals at night after the daytime exposure that inhibited growth of the eyeball. Since myopia is most often caused by the eye being slightly too large this seems like a plausible explanation. It certainly makes more sense than the previous theory about spending too much time indoors - that somehow you would spend too much time focusing closely since distances indoors are limited.

The article you're referring to might be this one:

http://bjo.bmj.com/content/early/2017/06/12/bjophthalmol-201...

(Alas, it's not Open Access)

I also remember reading an earlier news article in Nature on this exact topic:

https://www.nature.com/news/the-myopia-boom-1.17120

That's fascinating. I didn't see this exact point in the Nature article linked below, but is it as simple as your body needing bigger eyes to see in the dark?

> I could be incredibly naive ... The country wouldn't have economic competition from big pharma

Yep.

The USA has to be the most egregious example of this, other countries aren't immune.

That's clearly not the case in all parts of the world. China and India often ignore patents and trade secrets to produce generic drugs for domestic use.

I often hear about how useful donating used prescription glasses are to people in need in other countries like Africa and China. I imagine this would be a similar program that would be aimed at prevention. I would think any influence of big pharma would affect prescription glasses distribution programs in the same way.

Reading glasses are for lens focusing, not for convergence. Prism glasses are for convergence issues, but are rarelt prescribed. No conspiracy theory needed.

No conspiracy theory was claimed. Here's one of the newer summaries of research on prisms for convergence issues, unfortunately in German, but the abstracts' in English:

https://link.springer.com/article/10.1007/s00347-014-3037-9

Which states quite clearly that horizontal prisms shouldn't get prescribed, only vertical prisms, and weaker ones than previously thought, which brings us right back to the fact that we need more competent developmental, behavioral functional optometry & orthopty.

Furthermore, you probably want to read this article by Rodenstock:

http://assets.markallengroup.com/article-images/image-librar...

It's unfortunately marketing material, however, it's also the only English resource I know that outlines the problems of:

* Listing's law in its original version only applying to distance vision * 'effective near astigmatism' * tilting of the intraocular lens

inside one document so you don't have to go crawling all over the literature to find them like I had to. Now think of how failing to properly correcting that influences accommodative strabismus via the accommodation-convergence reflex in anisometropic patients... Especially if the glasses ain't iseikonic and thus induce unwanted and unbalanced base in/base out prism.

Of course, Rodenstock has a patent on some of these corrections. While Hoya has a patent on freeform double surface lenses which makes everything way more complicated to optimize when you ain't Hoya, Zeiss has a patent on knocking out convergence using an infrared light source to measure pupil position, and on various multiphoton raytracing technologies for calculating corrections such as the one Rodenstock describes (leading to Rodenstock using a complicated workaround), and so on, dozens of patents locking everyone out of making an /optimal/ pair of glasses. Yes this makes all vendors about equally good, but only by making all of them, relatively speaking, mediocre. Each in their own special way.

And don't get me started up on contact lenses and how they relate to the difference between axial anisometropia, refractive anisometropia, and their hybrid. My point here, and in my other comments (https://news.ycombinator.com/item?id=16195742 & https://news.ycombinator.com/item?id=16195570):

There exists no conspiracy. There only exists cock-up, and lots of it. Hanlon's razor etc.

What are your thoughts on causes/treatment of astigmatism? Could lens distortion (away from optical center of a high minus lens) be a contributing factor over a long period of time? If so, could be an argument for using FF lenses. Apparently the Zeiss FF patent expired this month and Seiko's FF patent expired in 2016.

Rodenstock lenses are not widely available in the US. Looks like the Zeiss Individual SV will compensate for astigmatism caused by pantoscopic tilt, https://pdfs.semanticscholar.org/3e73/2da37ec9e17bd086b32095...

Some quotes from Chapter 1 of an open-access book on astigmatism: https://www.intechopen.com/books/astigmatism-optics-physiolo...

… visual tasks with significant downward gaze, such as reading, can alter corneal curvature owing to eyelid pressure ... Studies on the time course of astigmatism regression have revealed slower recovery after longer periods of reading ... continuous use of the medial rectus muscle, especially during near tasks, imposes a force on the cornea which increases its radius of curvature in the horizontal meridian resulting in a shift towards against-the-rule astigmatism...

… Larger pupil sizes—in low lighting conditions— increase the amount of higher order aberrations such as coma and may intensify the cylinder power in subjective/manifest refraction. Coma has been shown to be correlated with greater amounts of astigmatism …

… accommodative astigmatism is related to lens distortion due to inhomogeneous lens elasticity, variable constriction in ciliary muscles (which itself changes the lens power), and nonhomogeneous tension of the extraocular muscles during convergence (which causes corneal distortion…

… slight changes in cylinder power and axis (towards with the rule) occur during convergence alone … this change is seen in a small percentage of eyes … for those who experience such an alteration, separate spectacle prescriptions for near and far distance vision might be beneficial.

>What are your thoughts on causes/treatment of astigmatism? Could lens distortion (away from optical center of a high minus lens) be a contributing factor over a long period of time? If so, could be an argument for using FF lenses. Apparently the Zeiss FF patent expired this month and Seiko's FF patent expired in 2016.

Pfuuuh. Got a link? I honestly have to say I draw a blank in regards to what you mean by "FF lenses", as I'd assume you wouldn't mean full frame lenses in the photography sense?

>Rodenstock lenses are not widely available in the US.

I know. They recently made an attempt to relaunch in the US but I have no idea if it succeeded.

>Looks like the Zeiss Individual SV will compensate for astigmatism caused by pantoscopic tilt, https://pdfs.semanticscholar.org/3e73/2da37ec9e17bd086b32095....

Yepp, but that's not the main problem. The main problem comes from the cyclotorsion the eyes exhibit during convergence as part of the donward gaze. This fundamentally changes the astigmatism axis.

I didn't go into this in my earlier post (Which I'll link here, since it's in a different sub-thread: https://news.ycombinator.com/item?id=16195742), but actually, to expand on this, I consider cyclotorsion a HUGE problem in the successful measurement of astigmatism.

I've tested this empirically quite a few times, and the traditional cover test fails to fully interrupt the fusional circuit in the brain, the cyclotorsion component remains active until the other eye is closed consciously.

(In fact, I speculate that even then it remains partially active, and in some cases only a temporary concious supression of the [inside-of-your-eyelids] image leads to a full disengagement of the circuit. But this is highly speculative, take this part with a large grain of salt.)

I consider this a problem because:

1. Cycloplegia in fact fails to prevent cyclotorsional adjustment.

2. Incorrect astigmatism correction can lead to amblyopic suppression, which can lead to (micro)strabismus, which leads to diplopia. Now, horizontal prisms aside, which we shouldN't prescribe, ever, except in EXTREMELY rare cases of total muscle paralysis or similar, this can then lead to an incorrect measurement of vertical deviation of the angle of gaze, which leads to an incorrect prism prescription, which... well, you get the point. Bonus if the astigmatism correction ends up so off, you end up affecting distance vision and cause accommodation. Double bonus if the patient already suffered from accommodative cramps [which btw. WON'T GET ANY BETTER if we keep the testing distance at 6 meters, which as, previously state, definitely DOESN'T equal optical infinity.]. Triple bonus if they didn't get cycloplegia to compensate for it at first. Quadruple bonus if the pupil dilation from the cycloplegia fucks up the astigmatism measurement [which is the point where wavefront measurements shine, because they can backinfere about the behavior of the narrower pupil even from the measurement of the widened pupil! But even wavefront measurement can't compensate for cyclotorsion! But of course that gets fucked up by wavefront mesurements that fail to consider the full pupil diameter!]

>Some quotes from Chapter 1 of an open-access book on astigmatism: https://www.intechopen.com/books/astigmatism-optics-physiolo....

>continuous use of the medial rectus muscle, especially during near tasks, imposes a force on the cornea which increases its radius of curvature in the horizontal meridian resulting in a shift towards against-the-rule astigmatism...

Interesting. Didn't know that one yet.

> Larger pupil sizes—in low lighting conditions— increase the amount of higher order aberrations such as coma and may intensify the cylinder power in subjective/manifest refraction. Coma has been shown to be correlated with greater amounts of astigmatism

Yepp, see my point about wavefront measurements.

>accommodative astigmatism is related to lens distortion due to inhomogeneous lens elasticity, variable constriction in ciliary muscles (which itself changes the lens power), and nonhomogeneous tension of the extraocular muscles during convergence (which causes corneal distortion…

True, but this ignores the cyclotorsional element.

>slight changes in cylinder power and axis (towards with the rule) occur during convergence alone … this change is seen in a small percentage of eyes

Small percentage my ass, that's a case of underdiagnosis due to insufficiently precise measuring equipment.

>for those who experience such an alteration, separate spectacle prescriptions for near and far distance vision might be beneficial.

or we can just, I don't know, PROGRESSIVELY ALTER THE ASTIGMATISM CORRECTION AS PART OF GLASSES? Using the same technology we already use for progressives? I know, I know, that'd seem TOO LOGICAL.

Sorry, I harbor the most bitter feelings on this topic.

> Should you ask the person trying to sell you a pair of expensive progressive lenses?

probably not, but should you ask the person trying to sell you an app with mediocre reviews of efficacy (the placebo effect should cause ratings to be higher than a "true" rating).

There is existing research on vision therapy and behavioral optometry, e.g. here's a 2002 review paper that covers preceding decades, http://www.familyvisioncare.org/2016/research/02_THE_SCIENTI...

If new business models (including software) for vision therapy emerge, the revenue can fund marketing of existing studies or even new studies. The presence of this (marketing?) article in the NY Times at least raises awareness of the concept, so that people can consult the research or ask a professional about non-lens options.

Any recommendations for 3d magazines? I want to buy on amazon if you have a link.

Search for "stereogram".

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