Charles wrote:
It just seemed more than reasonable to me that
- quote -

If you look at the anatomy of the extraocular muscles, you'll find they
exert primarily a tangential pull on the eye, which causes it to turn,
not to elongate.


The anatomy of the eye would say whether this is even
- quote -

The anatomy speaks for itself. That is not to say that what you are
suggesting is "impossible", and I do believe that small forces over long
periods of time can and do influence the shape of the eye.

- quote -

In over 30 years of practice and monitoring thousands of eyes developing
over time, I've seen little change in most peoples' astigmatism. I've
seen large changes in myopia, but relatively little in astigmatism
(except for eyes that are injured or diseased, or those that have been
subjected to long term contact lens wear).

w.stacy, o.d.

"Charles" <nospam[at]nospam.com> wrote

- quote -

You're right about that.. the outside (pointing) muscles are hugely
different from the ring-shaped inside muscles that you use to focus. But
they are hardwired together so that you can't converge without
accommodating, and vice versa. You use the same effort to produce both
effects, in a predictable ratio.

-MT

William Stacy wrote:

- quote -

Help me to understand. The muscles you are considering here are the
ones that "point" the eyes, right? These are the ones under stress
while I'm converging them for the tranaglyph. If those muscles were
having trouble, how would that make my vision blurry? Isn't that
determined by different muscles, the ones that do the actual focusing?

--

William Stacy wrote:


- quote -

You're the expert. It just seemed more than reasonable to me that
perhaps straining to cross the eyes over the long term might actually
pull on the eyeball in one dimension causing elongation and
astigmatism. The anatomy of the eye would say whether this is even
possible, and which dimension the astig would be in if it were
possible. I'm a total lay person, so if you say the data and/or
anatomy doesn't support this, I believe you.

Is there data on the astigmatism impacts of extreme close work? I say
"extreme" because my theory was that if I'm starting with eyes that
want to tend more outward than normal, "normal" close work might affect
my visual system in the same way as repairing watches (or whatever)
would for the average person.

CatmanX wrote:

- quote -

Absolutely not. I just hoped that I would not be mocked when I feel
that my "theory" is at least conceivable. An explanation of why I'm
wrong (for example, is the anatomy of the eye such that straining to
cross the eyes could temporarily flex the eyes and change their shape,
or not?), or a statement that research has proved otherwise, would
suffice. Better yet, a plausible explanation (besides pure randomness)
of the symptoms I'm seeing, like my vision getting worse when I started
doing more close work, would be great.

- quote -

Okay. Interesting how previous replies would indicate that I'm a moron
for even considering that how the eyes are used could affect
astigmatism at all. Something about peoples' ears not changing shape
from listening too hard.

- quote -

Help me understand the difference. I think the diagnosis was made
based on my explanation of symptoms and the movement of each of my eyes
when covered. Possibly also based on my verbal indication of when it
became difficult for me to maintain convergence/divergence with prism
lenses (I'm assuming, she didn't tell me what was actually happening
all the time). How are the symptoms different between brain related
convergence problems and physiological issues (exophoria?).

- quote -

If the natural resting state of my eyes is slightly outward, is prism
appropriate? If not, when is it?

--

In article <Sckhf.597045$xm3.317069[at]attbi_s21> ,
"Charles" <nospam[at]nospam.com> wrote:

- quote -

I was just trying to make a point, that just because something *seems*
like it ought to work a certain way, that doesn't mean that it actually
works that way.

--
Dan Abel
dabel[at]sonic.net
Petaluma, California, USA

What do you expect from a usenet group? Everyone to listen to your
arguement and agree??

There is plenty of research showing astigmatism developing according to
the direction of eye movement, but it relates more to the lid pressure
than anything else, not eye muscles.

Secondly, the problem you have is convergence insufficiency, not
exophoria. In CI, you ability to converge is impaired. The vision
therapy you are doing is to train your system to be able to converge
with ease. Prism correction will not achieve anything as the underlying
issue is an inhibitory centre in your brain and this inhibitory pathway
must be overridden in order to get you working comfortably for close
work.

grant

Dan Abel wrote:

- quote -

Wow, I'm pretty disappointed in this group. Is it really inconceivable
to the point of absurdity that if you use your eyes in ways that strain
and pull them that they might change shape slightly? As I said, it may
not actually be true, but you need to either do better than this or
just keep quiet about it.

--

Charles wrote:

- quote -

He may be a prolific writer, but I think he is pretty far out of the
mainstream of thinking in the field, or at least he was when the article
was written 18 years ago.

- quote -

I don't disagree that extended computer use has precipitated an increase
in myopia. I've obvserved it over the years. I think you were referring
to short term stresses doing the same thing, which is what I challenged.

- quote -

There are loads of data on this. Everyone knows that myopia is largely
an effect of excessive close environment of the post-industrial age. The
devil is in our inability to prevent it.

- quote -

No argument there.


- quote -

Human skeletal muscle, when continuously stimulated, tends to retain a
semi contracted state for a period after such stimulation.

w.stacy, o.d.

In article <RC6hf.568917$x96.4862[at]attbi_s72> ,
"Charles" <nospam[at]nospam.com> wrote:



- quote -


I'm retired now. I recommend it highly, although the pay isn't great.


:-)


I try to walk three hours a day. I often do more. This is very good
for my health. Of course, I have to realize that all this walking is
going to shorten my legs. Isn't it?

Wait a minute! Doesn't exercise make things *bigger*? Shouldn't my
legs actually get longer because of my walking?

I am anxiously waiting all of your expert opinions about whether my legs
are going to get shorter or longer because of all my walking. After
all, should I stock up on longer or shorter pants?

:-)

--
Dan Abel
dabel[at]sonic.net
Petaluma, California, USA