Accomotrac lessens myopia
Doug172
device, when used properly in a doctor's office, can enable a person with
myopia to lessen the severity of the myopia using biofeedback techniques.
Depending on the person's prescription, the technique can take weeks or
months to achieve results.
Has anyone had any experience with this, either good or bad? Does anyone
know of any doctors in North Carolina using this apparatus?
Thank you!!
Alex Eulenberg
I don't have any personal experience, but I can give you some references.
The man who invented this device is Joseph N. Trachtman, OD, PhD. You
can write for more information at...
Institute for Advanced Vision Technology
26 Schermerhorn St.
Brooklyn Heights, NY 11201
Here are some articles on the product, written by its developers:
* Randle, RJ. 1988. Responses of myopes to volitional control
training of accommodation. Ophthalmic Physiol Opt 8, 333-40.
* Roscoe, Stanley N. & Donald H. Couchman. 1987. Improving visual
performance through volitional focus control. Human Factors 29, 311-325.
* Trachtman, J.N. 1987. Biofeedback of accommodation to reduce
myopia - A review. Am J Optom Physiol Opt. 64(8), 639-643.
* Trachtman, J., Giambalvo, V., and Feldman, V. 1981. Biofeedback of
accommodation to reduce functional myopia. Biofeedback-Self-Regul.
6(4), 547-62.
Although any people have reportedly extended their "far point" of vision
after using the device, several controlled experiments published in
optometry journals show that the control group improves no better than
the experimental group. The latest is...
* Koslowe, K.C.; Spierer, A.; Rosner, M.; Belkin, M. 1991. Evaluation
of Accommotrac Biofeedback Training for Myopia Control. Optometry
and Vision Science. 68, 338-43.
Trachtman et al's response was printed in the March issue of the next
year (Optom Vis Sci 69, pp. 252-254).
An optometrist I once met says that it costs something like $75 a
session to use the device. Terribly overpriced in my opinion,
considering there are so many absolutely free ways you can monitor your
accommodation!
--Alex
Paul Harris
>
>I have heard about a device called an Accomotrac. As I understand it,
this
>device, when used properly in a doctor's office, can enable a person
with
>myopia to lessen the severity of the myopia using biofeedback
techniques.
>Depending on the person's prescription, the technique can take weeks
or
>months to achieve results.
>
>Has anyone had any experience with this, either good or bad? Does
anyone
>know of any doctors in North Carolina using this apparatus?
The device itself is interesting. I have had one for nearly 15 years.
My understanding is that there are only about 200-250 of these in the
world. Mine is number 15.
I feel that the claims made by the manufacturer and inventor were
overstated. The instrument by itself will do nothing to a person. VT
is something that the person must do for themselves. The Accommotrac
is an instrument to provide biofeedback to the person using the
instrument to "know" or to "get a sense of" how they are focused.
40 times a second an infrared system based on a Badal optometer
measures accommodation and converts the measurement to a sound. The
sounds then changes dynamically with accommodation. By working the
sound higher and higher the person is learning to harness negative
accommodation again and can, at first, for short and then for longer
and longer periods of time dynamically focus at distance and clear
things up. At first the refraction does not change only negative
accommodation. OVer time (6-8 months) the refraction does begin to
change.
Problems with the machine include the fact that it is best used in a
dark room with the person staying perfectly steady. Even the slightest
movement causes the system to go out of alignment changing the readings
in a way that has nothing to do with the level of accommodation the
patient is using. It also only measures one eye. Some of us have
wondered if it really is measuring accommodation or is just a very
expensive pupillometer registering instead the total amount of light
reflected back to the instrument rather than accommodation??? Anyway,
the pupil changes generally parallel the lens changes but I would like
the thing to be cleaner than it is.
IMHO, used alone for VT for myopia control (as was recommended by the
inventor) will not provide lasting changes. We use it as an additional
tool as part of a much more complete myopia control program. Different
people react to different activities and using only one means that some
won't get the effects necessary and those that do may not get as much
change as is possible with a more broad approach.
Lastly, there is an alternative instrument from England called the
Laserspec which uses a laser speckle pattern machine which gives direct
visual feedback as to where one is focused in space. It is less
expensive and has none of the limitations of the Accommotrac.
As to your last point, I know of OD's doing VT in North Carolina but I
do not know who has the device. If you want a list of those with the
Accommotrac you can contact Dr. Joe Trachtman in Brooklyn NY.
Paul Harris, O.D., F.C.O.V.D., F.A.C.B.O.
Director, Baltimore Academy for Behavioral Optometry
Erol Basturk
Paul Harris <ba...@ix.netcom.com> wrote:
>In <4fakiq$g...@newsbf02.news.aol.com> dou...@aol.com (Doug172) writes:
[...]
>the person is learning to harness negative
>accommodation again and can, at first, for short and then for longer
>and longer periods of time dynamically focus at distance and clear
>things up. At first the refraction does not change only negative
>accommodation. OVer time (6-8 months) the refraction does begin to
>change.
I am surprised you mention negative accomodation. I have read
the papers of Ebenholtz on accomodation hysteresis and negative accomodation,
but I thought this was still a relatively new and controversed notion.
It seems that in your statement, you are implying that
myopia onset and progression is a direct result of the loss
of negative accomodation.
The negative accomodation theory is quite attractive to explain the acuity
adaptation process in the early stage of development of the child.
However, I find it doesn't seem to fit very well with the existing theories on
the mechanism of accomodation, which are all somewhat unidirectional
(Helmoltz, Schachar,...). Of course, one could argue that the
maximum relaxation of the ciliary muscle (relaxation of the ciliary muscle
seems always associated with distance accomodation) corresponds to the
maximum level of negative accomodation from the dark focus position.
In which case, the dark focus is really a default level of nervous energy
in the ciliary muscle.
[...]
>IMHO, used alone for VT for myopia control (as was recommended by the
>inventor) will not provide lasting changes. We use it as an additional
>tool as part of a much more complete myopia control program. Different
>people react to different activities and using only one means that some
>won't get the effects necessary and those that do may not get as much
>change as is possible with a more broad approach.
I tried the accomotrac for a few months, and I must agree with
that statement. Changes were not lasting because (to my opinion) not
part of a comprehensive program. Maybe also because biofeedback doesn't
address the real cause of this loss of negative accomodation (which
is an interesting issue by itself).
[...]
>Lastly, there is an alternative instrument from England called the
>Laserspec which uses a laser speckle pattern machine which gives direct
>visual feedback as to where one is focused in space. It is less
>expensive and has none of the limitations of the Accommotrac.
>
This is interesting. I wasn't aware of this new device. Has it being
out for long ? I wonder how it compares to the Accomotrac in terms of
the accurary of the results. I always had a feeling that the Accomotrac's
limited accurary was importantly impairing the gain of "feel" of accomodation
by the patient.
cheers
Erol Basturk
Paul Harris
(Erol Basturk) writes:
>
>In article <4fd25b$d...@reader2.ix.netcom.com>,
>Paul Harris <ba...@ix.netcom.com> wrote:
>>In <4fakiq$g...@newsbf02.news.aol.com> dou...@aol.com (Doug172)
writes:
>
>[...]
>
>>the person is learning to harness negative
>>accommodation again and can, at first, for short and then for longer
>>and longer periods of time dynamically focus at distance and clear
>>things up. At first the refraction does not change only negative
>>accommodation. OVer time (6-8 months) the refraction does begin to
>>change.
>
>I am surprised you mention negative accomodation.
I am sure I have mentioned it in the past. To me this is a rather old
concept. The dark focus about which we have positive and negative
accommodation has been around in my thinking for at least 15-18 years.
> I have read
>the papers of Ebenholtz on accomodation hysteresis and negative
>accomodation,
>but I thought this was still a relatively new and controversed notion.
I don't know Ebenholtz but I would love some references.....
>It seems that in your statement, you are implying that
>myopia onset and progression is a direct result of the loss
>of negative accomodation.
>
I'm not sure "direct" or "indirect". One of the things we see is a
loss of both positive and negative accommodation about the central dark
focus point. Both sides drop in just prior to a reorganization of the
system which then shifts the dark focus and then reestablishes new
levels of positive and negative accommodation about either side of the
new dark focus. As a part of the progression the levels usually do not
come back to their original levels and over time there is a general
collapse. The progressive myope can't clear the normal amounts of
minus lenses at near!
The neurology supports this. All nerves fire all the time. The rest
position - dark focus - then is simply the steady state of the firing
in the accommodative mechanism about which it oscilates + and -. This
is how all the neurology works. There is no difference here. I see no
opposition to Helmholtz or Schachar here at all. They are talking
about the physiology which the person uses to accommodate with.
>The negative accomodation theory is quite attractive to explain the
acuity
>adaptation process in the early stage of development of the child.
>However, I find it doesn't seem to fit very well with the existing
theories on
>the mechanism of accomodation, which are all somewhat unidirectional
>(Helmoltz, Schachar,...). Of course, one could argue that the
>maximum relaxation of the ciliary muscle (relaxation of the ciliary
muscle
>seems always associated with distance accomodation) corresponds to the
>maximum level of negative accomodation from the dark focus position.
>In which case, the dark focus is really a default level of nervous
energy
>in the ciliary muscle.
>
Yup.
>[...]
>
>>IMHO, used alone for VT for myopia control (as was recommended by the
>>inventor) will not provide lasting changes. We use it as an
additional
>>tool as part of a much more complete myopia control program.
Different
>>people react to different activities and using only one means that
some
>>won't get the effects necessary and those that do may not get as much
>>change as is possible with a more broad approach.
>
>I tried the accomotrac for a few months, and I must agree with
>that statement. Changes were not lasting because (to my opinion) not
>part of a comprehensive program. Maybe also because biofeedback
doesn't
>address the real cause of this loss of negative accomodation (which
>is an interesting issue by itself).
>
Yup again.
>
>>Lastly, there is an alternative instrument from England called the
>>Laserspec which uses a laser speckle pattern machine which gives
direct
>>visual feedback as to where one is focused in space. It is less
>>expensive and has none of the limitations of the Accommotrac.
>>
>
>This is interesting. I wasn't aware of this new device. Has it being
>out for long ? I wonder how it compares to the Accomotrac in terms of
>the accurary of the results. I always had a feeling that the
Accomotrac's
>limited accurary was importantly impairing the gain of "feel" of
accomodation
>by the patient.
>
>
Also, not really new. Been around about 10-12 years maybe longer.
Unfortunately, the company, Scientifica Cook in the UK is now out of
business. We'll have to reverse engineer the thing and make our own
devices now. I'm told that there is only about $25-50 of parts in the
thing but it sold for over $3000.00!!!!
Erol Basturk
Paul Harris <ba...@ix.netcom.com> wrote:
>>
>>I am surprised you mention negative accomodation.
>
>I am sure I have mentioned it in the past. To me this is a rather old
>concept. The dark focus about which we have positive and negative
>accommodation has been around in my thinking for at least 15-18 years.
>
My surprise was really the linking of loss of negative accomodation to
myopia. I don't recall having read this topic debated on this newsgroup
before (maybe I missed it).
>> I have read
>>the papers of Ebenholtz on accomodation hysteresis and negative
>>accomodation,
>>but I thought this was still a relatively new and controversed notion.
>
>I don't know Ebenholtz but I would love some references.....
>
Here are some refs
Accommodative hysteresis
1. S. M. Ebenholtz, Accommodative hysteresis as a function of target-dark focus
separation, Vision Research 1992, 32(5):925-929
2. S. M. Ebenholtz, Accommodation hysteresis: Fundamental asymmetry in decay role
after near and far focusing, Investigative Ophthalmology & Visual Science 1991,
32:148-153
3. S. M. Ebenholtz, Long-term endurance of adaptive shifts in tonic accommodation,
Ophthalmic & Physiological Optics 1988, 8:427-431
4. S. M. Ebenholtz, Accommodative hysteresis: Relation to resting focus, American
Journal of Optometry & Physiological Optics 1985, 622:755-762
5. S. M. Ebenholtz, Accommodative Hysteresis: A Precursor for Induced Myopia ?,
Investigative Ophthalmology & Visual Science 1983, 24:513-515
>The progressive myope can't clear the normal amounts of
>minus lenses at near!
>
I am not sure to understand what this means (that the dark focus is
brought closer and closer by wearing negative lense ?)
>The neurology supports this. All nerves fire all the time. The rest
>position - dark focus - then is simply the steady state of the firing
>in the accommodative mechanism about which it oscilates + and -. This
>is how all the neurology works. There is no difference here. I see no
>opposition to Helmholtz or Schachar here at all. They are talking
>about the physiology which the person uses to accommodate with.
>
Interesting.
Then the ciliary muscle is really unlike regular muscles (say a biceps)
in the sense that it is constantly and unconsciously "tensed".
Probably because physiologically
there are not other muscle to counter-act the action of
the ciliary muscle on the lense (no biceps-triceps couple in the accomodative
apparatus).
>devices now. I'm told that there is only about $25-50 of parts in the
>thing but it sold for over $3000.00!!!!
Same (or worst) with the accomotrac I heard. Trachman really found
a way to make money (besides deliberately overcharging his patients
who are covered by an insurance policy,
as experienced by a friend of mine). Sad.
I am curious as to the relation between dark focus and the
psychological understanding of depth. Has it been investigated ?
From my experience, the higher the myopia (or maybe the rate of
myopia progression), the dimmer this
"sensation" of depth is, even with 20/20 correction.
If such a relation exists, it might explain the limited success of
the accomotrac and similar "one-eyed" biofeedback devices.
Thanks
Erol Basturk
Alex Eulenberg
>I am surprised you mention negative accomodation.
Paul Harris <ba...@ix.netcom.com> wrote:
>I am sure I have mentioned it in the past. To me this is a rather old
>concept. The dark focus about which we have positive and negative
>accommodation has been around in my thinking for at least 15-18 years.
The phrase "negative accommodation" in the optometric literature goes
quite far back. Here are some snippets from article from the Optical
Journal and Review of March 12, 1914.
* * *
POSSIBILITIES OF NEGATIVE ACCOMMODATION
By Eugene E. Heard, Pittsburgh, Pa.
I believe the value of practising voluntary relaxation is not
appreciated at the present time. ...
The countless thousands who toil in the offices of our large cities from
morning until night, subject their eyes to a tax such as their forebears
never knew, and when we remember that the eyes are capable of only three
and a half hours of continuous application without strain, one can
easily see why these people should be taught one of their most priceless
means of relief from strain due to keeping their eyes too long in exact
focus.
Few, indeed, realize that after a little practise they have the power of
relaxing the ciliaries more completely and naturally than can be done by
cycloplegics, and accomplishing it more readily ....
I beg to argue that this so-called fact, the accommodation being relaxed
in the normal eye for infinity, is mere theory, as there can be no proof
when in any particular person the ciliaries are absolutely relaxed ...
Relaxation is not proven by the inability to read when under the
influence of a cycloplegic ... for these muscles are very likely to have
been paralyzed in exactly the same cramped position in which they were,
at the moment of application of the drug. In other words, I say that
paralyzation is not necessarily relaxation; they may be unable to
accommodate, but still be cramped. This is probably what happens when
drugs are used, for in no other way, as reasonable, can we optometrists
account for the constantly increasing number of cases coming to us,
having failed to get relief from oculists who had put them under these
various cycloplegics, the cramp not being revealed by their method, as
it was not relaxed, but locked up. ...
This voluntary relaxation which I advocate is easy to learn when
constantly practised for a few weeks. Each effort renders the next a
litle more effective. It can be quickly practised a few times at odd
moments while waiting for a street car, waiting in a restaurant and
between the acts at a theatre. ...
I can hear my critics say, "more plus--more plus," but I was on the
firing line for "plus" lenses when there were so few there that I felt
lonely, and after many years of wearing an excess plus and also after
having prescribed for many thousand cases, have found that all of the
cramp cannot be unlocked that way, and that the brain must be taught to
help out the accommodative as well as the extrinsic muscles, in their
effort to relax with the aid of proper lenses ...
The writer has had very encouraging results along this line, having
succeeded in getting nervous cases to accept much more plus than was at
all possible to tolerate by the usual methods, besides teaching them a
resource for immediate rest that they did not know they possessed.
* * *
Unfortunately, the author does not elaborate upon his method for
teaching voluntary relaxation of the accommodative muscles, but it is
obvious that it does not require any fancy electronic biofeedback
equipment, since it can be "practised at odd moments" throughout the day.
Well, where have we come since 1914? Why don't we hear more about
negative accommodation? Have the scientists finally proven that
cycloplegics really do relax the eyes completely after all?
Once again I think it is appropriate to quote J.G. Sivak, a prominent
myopia researcher from the University of Waterloo, who wrote the
following in the journal Optometry and Vision Science, Vol. 68, no. 10,
p. 828 (emphasis mine):
"The suggested link between accommodation and myopia is not new, nor did
it originate in the optometric literature. Both Donders and Helmholtz
believed that excessive accommodation could lead to myopia, and a
variety of mechanisms, including accommodative increases in intraocular
pressure and permanent accommodative lenticular change, have been
suggested. However, suggested mechanisms, of whatever type, must be
considered with some skepticism when THE OVERALL MECHANISM OF HUMAN
ACCOMMODATION ITSELF IS STILL NOT COMPLETELY UNDERSTOOD AND QUESTIONS
SUCH AS THE SIZE AND IMPORTANCE OF NEGATIVE ACCOMODATION ARE STILL
UNCLEAR."
--Alex
Paul Harris
(Erol Basturk) writes:
>
>In article <4fm13v$4...@cloner2.ix.netcom.com>,
>Paul Harris <ba...@ix.netcom.com> wrote:
>>>
>>>I am surprised you mention negative accomodation.
>>
>>I am sure I have mentioned it in the past. To me this is a rather
old
>>concept. The dark focus about which we have positive and negative
>>accommodation has been around in my thinking for at least 15-18
years.
>>
>
>myopia. I don't recall having read this topic debated on this
newsgroup
>before (maybe I missed it).
>
I'm not sure it has been talked about here but it is central (IMHO) to
the understanding of the process whereby a person becomes myopic.
There is a phase in the cycle of change where the accommodative ranges
as measured by using binocular sphere powers at near (16 inches) with a
relatively small target (block of 20/20 letters for that distance) and
seeing how much plus and how much minus lenses the person can clear.
Without getting too specific we expect in a non-presbyope (younger than
45) for the person to be able to clear plus and minus 2.50 diopters in
this situation.
The progressive myope, not only has lost distance visual acuity, had
the refraction shift into minus (nearsightedness) but their ability to
clear minus at near in the set up noted above is usually very
depressed. This means that both positive and negative accommodation
are collapsed at this moment in time. This is when the person is most
vulnerable to getting more nearsighted and also when treatment
(relative plus for near and/or VT ) is most helpful.
>>The neurology supports this. All nerves fire all the time. The rest
>>position - dark focus - then is simply the steady state of the firing
>>in the accommodative mechanism about which it oscilates + and -.
This
>>is how all the neurology works. There is no difference here. I see
no
>>opposition to Helmholtz or Schachar here at all. They are talking
>>about the physiology which the person uses to accommodate with.
>>
>
>Interesting.
>Then the ciliary muscle is really unlike regular muscles (say a
biceps)
>in the sense that it is constantly and unconsciously "tensed".
>Probably because physiologically
>there are not other muscle to counter-act the action of
>the ciliary muscle on the lense (no biceps-triceps couple in the
accomodative
>apparatus).
Correct. Here the agonist-antagonist relationship is in the neurology
rather than with opposing muscles. Based on the insertion patterns of
cilliary muscles (very complex) it is possible that the same nerve is
really a nerve complex and that the two different muscle types would be
represented by different complexes within the single structure we call
the cilliary muscle. (The prior statement is wholly my own
conjecture.)
>
>>devices now. I'm told that there is only about $25-50 of parts in
the
>>thing but it sold for over $3000.00!!!!
>
>Same (or worst) with the accomotrac I heard. Trachman really found
>a way to make money (besides deliberately overcharging his patients
>who are covered by an insurance policy,
>as experienced by a friend of mine). Sad.
>
I fully agree it's sad!
>I am curious as to the relation between dark focus and the
>psychological understanding of depth.
In what manner are you using depth???? There have been lots of work
done on the Mandelbaum effect and its possible negative effect with
driving or flying a plane.
> Has it been investigated ?
>From my experience, the higher the myopia (or maybe the rate of
>myopia progression), the dimmer this
>"sensation" of depth is, even with 20/20 correction.
>If such a relation exists, it might explain the limited success of
>the accomotrac and similar "one-eyed" biofeedback devices.
>
There are certainly changes in spatial perception. They are very
different with CL's versus glasses in the myope as well.
Erol Basturk
Paul Harris <ba...@ix.netcom.com> wrote:
>In <4ftauq$j...@watnews2.watson.ibm.com> bas...@kivu.watson.ibm.com
>(Erol Basturk) writes:
>>
>>My surprise was really the linking of loss of negative accomodation to
>>myopia. I don't recall having read this topic debated on this
>newsgroup
>>before (maybe I missed it).
>
>I'm not sure it has been talked about here but it is central (IMHO) to
>the understanding of the process whereby a person becomes myopic.
>There is a phase in the cycle of change where the accommodative ranges
>as measured by using binocular sphere powers at near (16 inches) with a
>relatively small target (block of 20/20 letters for that distance) and
>seeing how much plus and how much minus lenses the person can clear.
>Without getting too specific we expect in a non-presbyope (younger than
>45) for the person to be able to clear plus and minus 2.50 diopters in
>this situation.
>
>The progressive myope, not only has lost distance visual acuity, had
>the refraction shift into minus (nearsightedness) but their ability to
>clear minus at near in the set up noted above is usually very
>depressed. This means that both positive and negative accommodation
>are collapsed at this moment in time. This is when the person is most
>vulnerable to getting more nearsighted and also when treatment
>(relative plus for near and/or VT ) is most helpful.
>
I went to person doing VT in my area about 2 years ago. She did all
kind of mesurements. She mesured how much I could clear at near as well as
convergence tests. I don't recall all the details, but it seems
to correspond to the tests you are describe.
I am a progressive myope, but to my surprise the optometrist
told me that there was not many parameters she could work with
and VT excercises wouldn't bring me much. How is this possible ?
>
>Correct. Here the agonist-antagonist relationship is in the neurology
>rather than with opposing muscles. Based on the insertion patterns of
>cilliary muscles (very complex) it is possible that the same nerve is
>really a nerve complex and that the two different muscle types would be
>represented by different complexes within the single structure we call
>the cilliary muscle. (The prior statement is wholly my own
>conjecture.)
>
From what I recall, the ciliary muscle is composed of 3 types of
fibers: radial, longitudinal and circular, but somehow they are all connected
to the same nerve. I found Schachar's theory quite interesting, but
haven't found other theories on the mechanism of accomodation which
take into account these different muscles as opposed to a generic
"ciliary muscle".
>
>>I am curious as to the relation between dark focus and the
>>psychological understanding of depth.
>
>In what manner are you using depth???? There have been lots of work
>done on the Mandelbaum effect and its possible negative effect with
>driving or flying a plane.
>
Are you referring to the accomodation at dark focus when there are
not contrast to accomodate on (like a blue sky for example) ?
I wonder for example what is the effect of undercorrecting. Does the
resulting decrease in contrast tell the visual brain to give up
negative accomodation and stay at the dark focus ?
Also, I always wondered why a myope (I) can consciously control
positive accomodation but negative accomodation is totally out of reach.
Is it as well true for the hyperope that he/she can control
consciously negative accomodation but can't control positive accomodation ?
Thanks
Erol Basturk
Paul Harris
Snip.....
>
>I went to person doing VT in my area about 2 years ago. She did all
>kind of mesurements. She mesured how much I could clear at near as
well as
>convergence tests. I don't recall all the details, but it seems
>to correspond to the tests you are describe.
>
>I am a progressive myope, but to my surprise the optometrist
>told me that there was not many parameters she could work with
>and VT excercises wouldn't bring me much. How is this possible ?
>
Beats me. Why don't you E-mail me her name and that might help me
explain..... I'm sure you are familiar that in any field there are
those that stay current and those that don't......
>>
>>Correct. Here the agonist-antagonist relationship is in the
neurology
>>rather than with opposing muscles. Based on the insertion patterns
of
>>cilliary muscles (very complex) it is possible that the same nerve is
>>really a nerve complex and that the two different muscle types would
be
>>represented by different complexes within the single structure we
call
>>the cilliary muscle. (The prior statement is wholly my own
>>conjecture.)
>>
>From what I recall, the ciliary muscle is composed of 3 types of
>fibers: radial, longitudinal and circular, but somehow they are all
connected
>to the same nerve. I found Schachar's theory quite interesting, but
>haven't found other theories on the mechanism of accomodation which
>take into account these different muscles as opposed to a generic
>"ciliary muscle".
me neither.... as I said I included a good bit of my own conjecture in
the above.
>>
>>>I am curious as to the relation between dark focus and the
>>>psychological understanding of depth.
>>
>>In what manner are you using depth???? There have been lots of work
>>done on the Mandelbaum effect and its possible negative effect with
>>driving or flying a plane.
>>
>Are you referring to the accomodation at dark focus when there are
>not contrast to accomodate on (like a blue sky for example) ?
>
No. getting locked in at the dark focus distance in the pressence of a
stimuli at that distance. Ex. rain drops on a wind shield....
>I wonder for example what is the effect of undercorrecting. Does the
>resulting decrease in contrast tell the visual brain to give up
>negative accomodation and stay at the dark focus ?
>
No.
>
>Also, I always wondered why a myope (I) can consciously control
>positive accomodation but negative accomodation is totally out of
reach.
Active relaxation in any system is difficult. You can tense just about
any muscle in your body very easily. Can you, to the same degree,
relax the same muscle????? I don't think so..... with lot's of yoga
maybe...
>
>Is it as well true for the hyperope that he/she can control
>consciously negative accomodation but can't control positive
accomodation ?
>
>
NO.
Raymond A. Chamberlin
>
>............several controlled experiments published in
>optometry journals show that the control group improves no better than
>the experimental group.
Sure glad that happened. Would be kinda sticky tryin' ta figger
out why a control group'd do better'n the jokers with the
machine.
Ray
Erol Basturk
Paul Harris <ba...@ix.netcom.com> wrote:
>
>>I wonder for example what is the effect of undercorrecting. Does the
>>resulting decrease in contrast tell the visual brain to give up
>>negative accomodation and stay at the dark focus ?
>>
>No.
If negative accomodation is still active and stays unconcious, I wonder why
a blurred distant object doesn't over time result in an increased
negative accomodation. Seems like the brain should have the ability
to adjust.
>Active relaxation in any system is difficult. You can tense just about
>any muscle in your body very easily. Can you, to the same degree,
>relax the same muscle????? I don't think so..... with lot's of yoga
>maybe...
I'm not sure what you mean here by "same degree". How can we
objectively compare a state of contraction and a state of relaxation ?
There seems to be a marked physiological difference between the
ciliary muscle and a regular muscle.
It seems the ciliary can relax as much as tense around the dark focus
value. I am not sure the same relationship exists for
regular muscles.
Maybe the capacity to relax in the ciliary can be hindered just like
for regular muscles when the person is under heavy stress (conscious or
unconscious). For example, some ppl under heavy stress can develop
muscles contraction and need to practice sophrology or similar
techniques to relax.
Related to this, I'd be very interested in reading what you think of
the hysteresis of accomodation as a precursor to myopia (Ebenholtz).
>>Is it as well true for the hyperope that he/she can control
>>consciously negative accomodation but can't control positive
>accomodation ?
>NO.
>
Are the symptoms of hyperopia onset similar to those of myopia onset,
namely the drop in accomodative range that you mentioned earlier ?
Also, is there such a thing as a progressive hyperope?
Thanks
Erol Basturk
Paul Harris
In <4gabql$h...@watnews2.watson.ibm.com> bas...@kivu.watson.ibm.com
(Erol Basturk) writes:
>
>In article <4g2v9u$1...@reader2.ix.netcom.com>,
>Paul Harris <ba...@ix.netcom.com> wrote:
>>
>>>I wonder for example what is the effect of undercorrecting. Does the
>>>resulting decrease in contrast tell the visual brain to give up
>>>negative accomodation and stay at the dark focus ?
>>>
>>No.
>
>If negative accomodation is still active and stays unconcious, I
wonder why
>a blurred distant object doesn't over time result in an increased
>negative accomodation. Seems like the brain should have the ability
>to adjust.
>
I must be REAL tired because I am not following what you mean by your
last paragraph at all.... sorry. Can you explain it better????
Stress, sustained near visual stress, like from reading and VDT's etc.
cause a collapsing of both the positive and negative accommodation
during the progression of myopia.
>>Active relaxation in any system is difficult. You can tense just
about
>>any muscle in your body very easily. Can you, to the same degree,
>>relax the same muscle????? I don't think so..... with lot's of yoga
>>maybe...
>
>I'm not sure what you mean here by "same degree".
As far along the scale away from the "zero" point (dark focus point).
> How can we
>objectively compare a state of contraction and a state of relaxation ?
>There seems to be a marked physiological difference between the
>ciliary muscle and a regular muscle.
>It seems the ciliary can relax as much as tense around the dark focus
>value. I am not sure the same relationship exists for
>regular muscles.
Again, I am talking about the neurological control rather than the
actual muscle itself......
>Related to this, I'd be very interested in reading what you think of
>the hysteresis of accomodation as a precursor to myopia (Ebenholtz).
>
I have ordered the articles. It will take a few weeks to get them and
I will be out of the country for a month starting March 8 (In Europe
lecturing)
>>
>Are the symptoms of hyperopia onset similar to those of myopia onset,
>namely the drop in accomodative range that you mentioned earlier ?
>
Yes.
>Also, is there such a thing as a progressive hyperope?
Yes.
William Stacy
writes:
>
>Yes.
Well that's news to me. Every moderate to high hyperope (~ +2 D. and
up) I ever ran into was about as stable as the Rock of Gibraltar.
Progressive hyperopia???
Maybe it's just semantics, but I don't think so...
William Stacy, O.D.
O:BASE Ophthalmic Systems
w...@ix.netcom.com
http://www.cybergate.com/~lovelea/obase.htm
Paul Harris
writes:
>In <4ge0nm$r...@ixnews2.ix.netcom.com> ba...@ix.netcom.com(Paul Harris )
>writes:
>
>>In <4gabql$h...@watnews2.watson.ibm.com> bas...@kivu.watson.ibm.com
>>(Erol Basturk) writes:
>
>>>
>>>Also, is there such a thing as a progressive hyperope?
>
>>
>>Yes.
>
>Well that's news to me. Every moderate to high hyperope (~ +2 D. and
>up) I ever ran into was about as stable as the Rock of Gibraltar.
>
>Progressive hyperopia???
Yes... This is the development of adverse hyperopia. The cause most
often is as a secondary iatrogenic disease caused by the overzealous
prescribing of plus.
I know you and others will say if a good cycloplegic were done.... and
things like ....latent hyperopia.....
I was a subject in a longitudinal study for 5 years as a child. All
this plus, A-Scans, Purkinje images measures of radius of curvature of
front cornea, rear cornea, front lens, rear lens, anthropomophic
measures, IOP, wet and dry refractions, full 21 point analytical and
more were done every 6 months for 5 years. I have the data on myself.
At no point did I ever show hyperopia more than +1.00 to +1.25.
After the study at age 15 I started wearing single vision plus to play
chess and this was upped and upped. NOTE: I was measured with a 14 to
1 ACA ratio. 16 eso at near through whatever distance lens of the time
and 2 eso with +1.00 add over that. The standard theory was "push
plus". This was done and I ended up at one point wearing +2.25 OD/
+2.50 OS with a +1.50 add for 10 years. I measured well up in +3.00
range when my father (my optometrist then) was done with me.
There was no latent hyperopia over the +1.00. The additional amounts
were built up slowly over time in response to my optometric care.
Once I did VT 13 years ago I now wear just some plus for near and
nothing for distance. My subjective now is +1.25 OU which I choose not
to wear and do great. In fact I now see better than ever.
I hope this explains a bit a very big subject which I am fully aware of
there will be little agreement on from the conventional eyecare
establishment. Please give me some other alternative to understand the
above findings over time. I also have basic optometric data on me from
the age of 6 months.
William Stacy
Very interesting data. Very interesting study (Was it published?).
I can believe you went from +1 to +2.5 or so (the 3 was likely
over-zealous plus pushing), although I'd call it unusual, and certainly
not like anything I've observed in young hyperopes over the years.
It's still a far cry from the 8 or 10 D. or more of change in the
progressive (aka pathologic) myopes. I'd choose a different name, if
you must have a name for such an occurrence, for consistency.
Maybe "hyperopia creep"? "Far-sighted slip"?
I can't resist: "the incredible shrinking eye"??
Bill
William Stacy
Paul Harris
LOTS snipped......
>Very interesting data. Very interesting study (Was it published?).
>
Yes in several places. Chief investigator was Bill Ludlum. The study
was so large that it was reported in sections. Most appeared in the
academy journal and others in the Journal of the AOA. I don't have the
references handy but could look them up if you wish. My case was
lumped into the 500 or so subjects that were followed.
>I can believe you went from +1 to +2.5 or so (the 3 was likely
>over-zealous plus pushing), although I'd call it unusual, and
certainly
>not like anything I've observed in young hyperopes over the years.
>
>It's still a far cry from the 8 or 10 D. or more of change in the
>progressive (aka pathologic) myopes.
I agree here fully. The +8 and +10 generally occur following a
different mechanism. Most of which occurs very early, 18-36 months
usually.
> I'd choose a different name, if
>you must have a name for such an occurrence, for consistency.
>
>Maybe "hyperopia creep"? "Far-sighted slip"?
>
>I can't resist: "the incredible shrinking eye"??
>
We just use "adverse hyperopia". Hope that suffices.
William Stacy
writes:
>LOTS snipped......
>
>>Very interesting data. Very interesting study (Was it published?).
>>
>
>Yes in several places. Chief investigator was Bill Ludlum. The study
>was so large that it was reported in sections. Most appeared in the
>academy journal and others in the Journal of the AOA. I don't have
the
>references handy but could look them up if you wish. My case was
>lumped into the 500 or so subjects that were followed.
That would be great. I'm sure others on s.m.v. would like to see it
too. I do have a quick question about it. What instrumentation was used
to measure the Purkinje images, yielding what kind of accuracy on the
various radii?
>(...)
>We just use "adverse hyperopia". Hope that suffices.
Another obvious question is how many cases of adverse hyperopic changes
(increases) did the study find, and in what amounts?
Thanks
Raymond A. Chamberlin
>
...
>
>I'd choose a different name, if
>you must have a name for such an occurrence, for consistency.
>
>Maybe "hyperopia creep"? "Far-sighted slip"?
>
>I can't resist: "the incredible shrinking eye"??
>
>
Let's put the lenses in the drugstore and let the optommies play
with words.
Ray
William Stacy
<ra...@sirius.com> writes:
>
>Let's put the lenses in the drugstore and let the optommies play
>with words.
>
>Ray
Oh sure. I never met a pharmacist who knew a diopter from a seg
height, or anisocoria from xanthelasma.
Raymond A. Chamberlin
>In <4gjsku$h...@sun.sirius.com> "Raymond A. Chamberlin"
><ra...@sirius.com> writes:
>
>>
>>Let's put the lenses in the drugstore and let the optommies play
>>with words.
>>
>>Ray
>
>Oh sure. I never met a pharmacist who knew a diopter from a seg
>height, or anisocoria from xanthelasma.
>
>
I was always told the proper response to that sort of thing was:
"You do and you'll have to clean it up!" Of course, I know that
a diopter is a double-fuselaged ornithopter.
Ray