Is axial change driven by ciliary muscle tone?

Emmetropisation via axial elongation or shortening driven by ciliary
muscle tone seems to make sense to me.

In such a model a particular longevity of contraction of the ciliary
would trigger some enzyme to create axial elongation to reduce this
tension.

Unconscious factors that created anxiety generating tonic (undesired)
accommodation in myopes would also tend to continue this process even
if the myope was not an habitual reader.

In such a model myopic dark focus/tonic accommodation even in sleep
might have more influence on a persons axial change than might be
evident from their daily habits.

This appears to be a testable hypothesis. From what i understand
there is quite a body of evidence that would support such a theory.
Perhaps i am mistaken.

What are the arguments against this theory?

 

Dear Andrew,

Great theory.

You are probably correct.

Best,

Otis

 

Birds of a feather flock together.

You are both wrong. Two birds with one stone.

DrG

 

Dear Andrew,

Your ar right again.

Here is a proven case where a woman cleared her distant
vision from -4 diopters.

http://www.optometrists.org/Boston/articles.html

These ODs will tell you that here "genetics" pre-programed
her vision to "clear" and had nothing to do with
her personal effort.

Vision clearing confirmed by a highly qualified optometrist.

The "second-opinion" lives.

I bet her chidren receive the full benifit of this second opinion.

Best,

Otis
Engineer

 

Dear Mike,

What is your point. Do you state that Andrew is
"wrong" and this woman did not
clear her vision as she stated?

Or would you say she had "pseudo" myopia
(not eye-length) and was able to "clear" for
that reason.

Of would you say she is a fraud, and pushing
an "unproven" preventive method?

If so, should she be called before a "Board" to
explain he "unproven" method?

If there is to be "change", then the mechanism
of the "second-opinion" should be encouraged -- not
supressed -- as you imply.

Please explain.

Best,

Otis

 

Statement by Antonio,

[She cleared to -1/2 diopter -- which would be about 20/40. She
could probably pass the standard DMV-Snellen test.]



Remembrances of a Myopia Past

When I was a child, I understood as a child. I did not know that
when people are under stress they "zero in" at near, stop looking far,
and stop processing peripheral light.4 I figured out, though, that it
was much easier to read and cast my eyes down than to deal with the
hallways full of teenagers in my large junior high.

I noticed in eighth grade, when I sat in the middle of the
auditorium that the people on the stage were blurry. I remembered that
the year before they had been clear from the back of the auditorium
where the seventh graders sat. I could still see the chalkboard but I
failed the school screening. My first glasses were -1.25 DS, OU and
with them I was given the power to see the veins on the leaves of the
trees at astounding distances. Was this the good vision I had lost?
After that I sat in the exam chair every year and demanded telescopic
sight. I did not have words for the extra stress those glasses put on
my accommodative system. I just took them off to read.

I did not know how to react to that panicky feeling brought on by
the loss of clear sight. The inevitability of visual deterioration was
the worst of it, with no way to stop the inexorable process of eyeballs
growing longer and longer, I thought. I strained harder to see in the
same way one might focus in dim light on tiny print at near. Soon I
needed the glasses for the chalkboard as well as the auditorium. There
was no one to tap my occipital bone and tell me to "see farther back in
the head," to "relax and look softly," and to "hang on to the
periphery."

I felt I was an oddity, a genetic mistake, totally unlike all of
my friends. Most people in those days had clear sight.5 Now we don't,
but our contact lens technologies and fashion frames have lulled us
into thinking myopia, rampantly increasing as it is, is not such a
loss. At age 12 in the fifties, though, it was socially and
aesthetically catastrophic to become a myope. I was known as the
"blonde bombshell" in junior high, but blondes were no longer
bombshells in girls' glasses with little rhinestones at the corners.
Later, when frames were small black cat eyes, good looks were still
elusive. With a prior self-image of beauty, I was suddenly caged in
ugliness. I wore them only in class. The rest of the time I moved in a
fog of vanity and became somewhat introverted. I stopped looking far. I
felt my personality change behind my very eyes. My mother wondered what
had happened to her "outgoing" daughter.

I was athletic and had won a letter the year before I became
nearsighted. It was much harder to catch a ball with my glasses on.
Things were smaller and closer than they were without my glasses, and I
was in a different place. Behind my frames, I was no longer in the
world, but looking into it, instead. There was fear of breaking glasses
then, too. They didn't have prescriptions in plastic then and the only
contacts available to athletes were large, painful scleral lenses. Our
babysitter wore them and my emmetropic mother looked at her coming up
the walk, goggle-eyed, and said, "Poor Susan."

My father was sorry that it was his "dominant" myopic genes that
had made us so blind. He gave me a book by oculist Dr. William Bates on
"better eyesight without glasses."6 At 13 or 14, I faithfully did the
exercises for three months, hoping to eliminate my then -2.50 DS with
cylinder myopic correction all at once. I surprised my ophthalmologist
that year because I did not get worse. He had predicted progression to
age 16.7 In fact, I never did get worse until a whiplash injury at 22
put me over the -3.00 DS mark,8 and during my second pregnancy an
appointment with an ophthalmologist unaware of hormones put me over the
-4.00 DS mark at age 29.

Perhaps I even got better after "doing Bates," but it was not part
of my doctor's model of vision to take minus away from a myope. I would
"grow into it all soon enough," I heard him tell my mother. If
perchance I was already full grown, these would give me "extra help"
when I learned to drive. Or so we thought.

I did not know that depth perception is affected by minus or that
when one has to over accommodate, convergence is pulled in more or
recalibrated. I just knew that space was so different in glasses that I
wasn't sure where things were any more. Once the driving instructor
used his brake when I was certain we could turn without hitting those
pedestrians.

I did not suspect that the higher the lens power, the more the
periphery is warped by the lens, because light is focused for the
benefit of foveal acuity at the expense of ambient vision. Nor did I
understand that the more the periphery is warped, the harder it is to
see the center clearly because you cannot judge how far it is without
accurate peripheral cues. All I knew was that I didn't feel safe
driving. I could not see anything out of the sides of my eyes and had
to whip my head back and forth and back forth and was in great danger
of losing sight of the middle of the road. The driving instructor told
me I had to keep my eyes straight ahead and not look to the side or I
would drive off in the direction I was looking. I tried to do that, but
it scared me so much I didn't take my test until I was 20.

I thought glasses gave me good vision, though, because I could see
the veins on the leaves of the faraway trees. I did not know that when
you're certain of what you see and where it is, that is good vision.
All I knew was that I didn't know what was there for sure without my
glasses, and with my glasses I wasn't sure where the what was. But I
was a child.

When I was 21, my husband delighted me on our honeymoon by saying
I was beautiful in glasses and, since I could not see him clearly
across the table without them, he would be honored if I would wear them
all the time. He was worrying about the risks of my hard (the old PMMA
type) contact lenses because they frequently slid off my corneas when
he was kissing me and had to be retrieved from somewhere awfully close
to my brain. I was glad to get rid of them because I couldn't read in
them any more easily than I could read in my glasses. By then there was
no longer any possibility of not wearing something-except for reading.

While I never read in glasses, I took notes in them. I sat through
high school and college and graduate school in them. No one ever
suggested a bifocal in class or plus spectacles over the contacts to
read. I told two contact lens specialists in two cities that I couldn't
read through my contact lenses. They both frowned and said "You should
be able to read through them," and that was that when I was a child.

When I was 31, I was cyclopleged because another ophthalmologist
thought my case-hardened coke bottle lenses were too strong. He gave me
a -3.87 DS and a -3.37 DS, which I wore until I learned to reduce my
myopia. I had to keep them by my bedside table, but I still took them
off to read.

 

Unconscious factors that created anxiety generating tonic (undesired)

trying to link your "anxiety" presumption into this huh?

tonic accommodation during sleep huh? why propose that?

I wonder what the effects of psychotherapy, or benzodiazepene anxiolytics,
would be?

Really? What evidence would that be.

Andrew, you are a legend in your own mind!

 

And she was an accommodative myope!

===================

 

Interesting.

I got into trouble with my definitions.

Evidently a ciliary with tonous in pseudomyopia does not have tonic
accommmodation.

Evidently tonic accommodation is exactly the same as dark focus of
accommodation.

Such confusing definitions dont help in my view.

Semantics aside this data is supportive of my theory.

My theory says the group with the most undesired myopic accommodation
will have the greatest degree of axial elongation, and those with the
most undesired hypermetropic relaxation of accommodation will have the
most axial shortening.

This study only measured dark focus accommodation but did not also
determine tension (evidently i cant say tonus) present during viewing a
visually compelling stimulus.

What i now need to know is how do the 3 groups differ in levels of
tonic accommodation that becomes apparent under cycloplegia that can be
separated from depth of field effects due to the enlarging pupil and
ideally this repeated for dark focus of accommodation when not
cyclopleged. Presumably a pinhole contact lens would be required for
all test conditions.

I would suspect that myopes have the most amount of tonic
accommodation. That might sound obvious but why should it be obvious?
Why should there be any relationship unless there is some underlying
connection between these observations?

So using that data (if what i suspect is the case) myopes who already
have large tonic accommodation when viewing a visually compelling
stimuli have only slightly more tonic accommodation at dark focus.

The question is, which of the 3 groups has the most tonic
accommodation?

If myopes are already focusing inwards due to anxiety then the small
difference between distance accommodation viewing a visually compelling
stimulus and dark focus accommodation makes sense.

Andrew

 

I said

will have the greatest degree of axial elongation, and those with the
most undesired hypermetropic relaxation of accommodation will have the
most axial shortening

I need an amendment. These would both create the same effect on the
ciliary.

Maybe its back to the drawing board for now.

:-(

Andrew

 

RM

Perhaps you need to share notes with Mike Tyner who believes that that
pseudomyopia is related to anxiety.

The fact is your esteemed learning institutions are clueless as to the
cause of myopia.

Perhaps you should consider that before you attack any ideas that run
contrary to your own set of beliefs
Andrew

 

If I understand Mike correctly, he disagrees with the hypothesis that
tonic accommodation is the stimulus to axial change. Please read the
header and refrain from getting off-topic.

With respect to the article about the woman who lost 4 diopters of
myopia is: so what? If most myopes responded to that type of therapy,
one could actually publish something other than an interesting case
study on the internet.

What I did notice is that as her myopia decreased, so did her
prescription.

DrG

 

Perhaps you need to share notes with Mike Tyner who believes that that

This is a possibility. Note the word PSEUDOmyopia.

With your big brain, you'll have it figured out in no time!

 

You have an hypothesis, not a theory.

To test this hypothesis:
1) Search for evidence that accommodation drives emmetropization. If you
search PubMed you will find dozens of studies with evidence that
accommodation is not involved in emmetropization

2) Search for evidence that prolonged accommodation is associated with axial
enlongation. You will find that there is a small effect for near work being
associated with myopia, however, you will also find that uncorrected
hyperopes, who experience accommodation all waking hours, do not have axial
enlongation.

3) Search for evidence that anxiety is associated with excess accommodation.

4) If you find evidence for 1, 2 and 3, then test on chickens: subject one
group of chickens to anxiety (pictures of foxes in the hen house?), leave
another group alone and see if the anxious group gets myopic.

Dr Judy

 

have you noticed that you have a tendency to piss-off everyone you talk
to. like the researchers from the singapore myopia group. do you
think its because you have a large ego and act like you know more about
everything than anyone else. you should work on that. i bet this has
been a lifelong problem for you. you need to get that under control so
you don't look like a horses ass at the news conference when they award
you the nobel prize.

 

Mike Tyner said

Could you list them please?
"dark focus" to the resting state in a featureless field. It's
approximately
the same as "tonic accommodation"

I understood dark focus to be the resting state in a featureless field,
such as blue sky or complete darkness. The study said "An
association between tonic accommodation, the resting accommodative
position of the eye in the absence of a visually compelling stimulus" .

I agree standard definitions are important. Do you mind giving it a go
to explain the difference please?
around huge loads of tonic accommodation.

Interesting. So the hyperopes have the most myopic tonic
accommodations and the myopes the least tonic accommodation? Thats how
i am now understanding this.

Thanks

Andrew

 

mike Tyner said

Thanks for confirming that.

One thing that really puzzles me is the effect that pseudomyopia has
during cycloplegia ie pseudomyopia reduces, versus the effect that the
enlarged pupil has ie more myopia is measured.

I have asked the following question before and it seems to have created
tension, but i am just wanting to understand this better thats all.

Have the competing effects of pseudomyopia and pupil size ever been
separated out and measured separately?

What i am getting at is,

1. how common are small amounts of pseudomyopia? As anybody ever
looked at a relationship between amounts of pseudomyopia and refractive
error?

Many many studies have been done on tonic accommodation, but I am
curious to know if anything similar has been done with pseudomyopia.

An i correct in believing that optically and measurably it is not
possible to separate out apparent changes in measured myopia created by
different pupil sizes, unless some calculation using before and after
pupil size is performed or when measuring myopia revealed by
cycloplegia a pin hole contact len is used?

Thanks

Andrew

 

Thanks Mike

That was a very clear answer. It had not occured to me that pupil
size effects were irrelevant when refracting and you explained that
well.

Cheers

Andrew