|
|
| Author |
Message |
retinula@hotmail.com
medicine forum beginner
Joined: 14 Nov 2005
Posts: 44
|
 Posted: Wed May 10, 2006 1:42 pm Post subject:
Myopia a side-effect of an Intelligence Gene?
|
|
|
Hello all,
here is an interesting and highly speculative article that I was
alerted to by dr. judy. I believe someone posting here a month or two
ago gave reference to this theory but a link was never posted.
perhaps, after reading this, many of the people who are so frustrated
about their myopia might consider it in a different light.
retinula
============
W. Mak, M.W.M. Kwan, T.S. Cheng, K.H. Chan, R.T.F. Cheung and S.L. Ho
Department of Medicine, Queen Mary Hospital, University of Hong Kong,
4/F, Professorial Block, 102 Pokfulam Road, Hong Kong, PR China
Medical Hypotheses 2006 vol. 66(6) Pages 1209-1215
Myopia as a latent phenotype of a pleiotropic gene positively selected
for facilitating neurocognitive development, and the effects of
environmental factors in its expression
Myopia has become an almost pandemic problem in many populations.
There are compelling evidence to suggest that myopia is a hereditary
condition. However, myopia would constitute a definite selection
disadvantage during most stages of human evolution, which is
incompatible with its moderate to high prevalence in most modern
populations. The rapid upsurge of myopia over just a few decades also
implies that its inheritance does not follow any of the usual
patterns, and environmental factors may have an important role in
precipitating its occurrence in those who are genetically predisposed.
Previous studies showed that myopes were, on average, more intelligent
than non-myopes, and this association had been attributed to a
biological link between eye growth and brain development. We propose a
pleiotropic genetic model to explain the atypical epidemiologic and
inheritance pattern of myopia and its relationship with neurocognitive
development. This pleiotropic gene was positively selected for its
facilitation of human intelligence. The myopic component is a latent
phenotype; myopia will not be expressed unless some novel external
factors are encountered (i.e. a "quirk" phenomenon). Therefore, the
myopic component was selectively neutral in our ancestral environment.
The net gain in Darwinian fitness enables the pleiotropic gene to
attain a high frequency in the human population, as reflected by our
current prevalence of myopia.
Shortened Link:
http://tinyurl.com/kusft |
|
| Back to top |
|
 |
tkopan1@yahoo.com
medicine forum beginner
Joined: 05 Apr 2006
Posts: 13
|
| Posted: Wed May 10, 2006 4:35 pm Post subject:
Re: Myopia a side-effect of an Intelligence Gene?
|
|
|
WHile I do not dispute the work of these learned researchers, I have a
hard time with the "genetic predisposition" aspect of this. While
certain types of high refractice error of all types has been shown to
be hereditary, vision, being a learned response, changes with the
amount of stress the visual system can handle.
Without trying to be racist or bigoted, we see a alot of high myopia in
the asian populations. These people, as a whole, have different view
of education and instill in their children the need to strive for
excellence. The Indian culture (from India) is much the same way in
the educated segment of their population.
Once you use up your ability to absorb visual stress (i.e. reading and
CRT use) after doing this task for hours at a time, your ciliary muscle
'cramps up' causing a blur at far which initially clears, but later can
become permanent by causing elongation of the eyeball which is, by
definition, myopia. This is why so many functionally/developmentally
trained optometrists apply reading lenses to young people. In some
cases, the child's eye is not ready to absorb these kinds of stresses
at such an early age. In Russia, I understand that learning to read is
delayed from 1-3 years. For this reason and they see less
nearsightedness accordingly.
This is what I was taught and how I have apporached this problem for
over 30 years with my patients. When you are right 9/10 of the time,
it is hard to chuck it all and start thinking exclusively genetics.
--Dr. Tom
retinula@hotmail.com wrote:
| Quote: | Hello all,
here is an interesting and highly speculative article that I was
alerted to by dr. judy. I believe someone posting here a month or two
ago gave reference to this theory but a link was never posted.
perhaps, after reading this, many of the people who are so frustrated
about their myopia might consider it in a different light.
retinula
============
W. Mak, M.W.M. Kwan, T.S. Cheng, K.H. Chan, R.T.F. Cheung and S.L. Ho
Department of Medicine, Queen Mary Hospital, University of Hong Kong,
4/F, Professorial Block, 102 Pokfulam Road, Hong Kong, PR China
Medical Hypotheses 2006 vol. 66(6) Pages 1209-1215
Myopia as a latent phenotype of a pleiotropic gene positively selected
for facilitating neurocognitive development, and the effects of
environmental factors in its expression
Myopia has become an almost pandemic problem in many populations.
There are compelling evidence to suggest that myopia is a hereditary
condition. However, myopia would constitute a definite selection
disadvantage during most stages of human evolution, which is
incompatible with its moderate to high prevalence in most modern
populations. The rapid upsurge of myopia over just a few decades also
implies that its inheritance does not follow any of the usual
patterns, and environmental factors may have an important role in
precipitating its occurrence in those who are genetically predisposed.
Previous studies showed that myopes were, on average, more intelligent
than non-myopes, and this association had been attributed to a
biological link between eye growth and brain development. We propose a
pleiotropic genetic model to explain the atypical epidemiologic and
inheritance pattern of myopia and its relationship with neurocognitive
development. This pleiotropic gene was positively selected for its
facilitation of human intelligence. The myopic component is a latent
phenotype; myopia will not be expressed unless some novel external
factors are encountered (i.e. a "quirk" phenomenon). Therefore, the
myopic component was selectively neutral in our ancestral environment.
The net gain in Darwinian fitness enables the pleiotropic gene to
attain a high frequency in the human population, as reflected by our
current prevalence of myopia.
Shortened Link:
http://tinyurl.com/kusft |
|
|
| Back to top |
|
|
Mike Tyner
medicine forum Guru
Joined: 24 Mar 2005
Posts: 1299
|
| Posted: Thu May 11, 2006 12:34 am Post subject:
Re: Myopia a side-effect of an Intelligence Gene?
|
|
|
<tkopan1@yahoo.com> wrote
| Quote: | vision, being a learned response, changes with the
amount of stress the visual system can handle.
|
Visual perception simply doesn't vary enough to make your assumption
possible.
Visual perception eg logMAR, color, and stereo acuity are easily measured
and they only vary with the obvious interference of drugs, cataracts,
refractive error and muscle or receptor fatigue. Those are "stressors" but I
gather that isn't the "stress" you mean. I'm not sure what "stress" is, and
neither are you. Insofar as vision is the pure neurological function of
assimilating sensory input, it's pretty constant after age 8 or so. So is
hearing.
But axial length is not neurological vision.
| Quote: | Without trying to be racist or bigoted,
we see a alot of high myopia in
the asian populations. These people, as a
whole, have different view
of education and instill in their children
the need to strive for
excellence. The Indian culture (from India)
is much the same way in
the educated segment of their population.
|
Then it must hold true for a diaspora of Jews, because they're nearsighted,
too.
| Quote: | Once you use up your ability to absorb
visual stress (i.e. reading and
CRT use) after doing this task for hours
at a time, your ciliary muscle
'cramps up' causing a blur at far which
initially clears, but later can
become permanent by causing elongation
of the eyeball which is, by
definition, myopia.
|
It's a heavily ingrained idea. It just don't work that way.
| Quote: | This is why so many functionally/developmentally
trained optometrists apply reading lenses to young people.
|
But for the last twenty years, doctors of all flavors have been taught that
these techniques were not worthwhile for myopia control, and that those who
recommend special glasses for myopia control are bilking the public. You
have an uphill climb trying to reverse such conventions.
| Quote: | In some cases, the child's eye is not ready to
absorb these kinds of stresses
at such an early age.
|
I don't know what "stresses" you mean. If "stress" is accommodation, then
there are lots of people who carry around a huge load of habitual
accommodation and they aren't more prone to nearsightedness. If "stress" is
something else then please be more specific.
| Quote: | In Russia, I understand that learning to read is
delayed from 1-3 years. For this reason and they see less
nearsightedness accordingly.
|
We agree that myopia is associated with more time spent reading. Myopia is
an adaptive response to near work. But easing accommodation with special
lenses does not significantly alter that correlation.
| Quote: | This is what I was taught and how I have apporached this problem for
over 30 years with my patients. When you are right 9/10 of the time,
it is hard to chuck it all and start thinking exclusively genetics.
|
Makes one wonder why the effect doesn't show up in controlled studies.
-MT |
|
| Back to top |
|
|
p.clarkii@gmail.com
medicine forum Guru Wannabe
Joined: 11 Sep 2005
Posts: 247
|
| Posted: Thu May 11, 2006 11:41 am Post subject:
Re: Myopia a side-effect of an Intelligence Gene?
|
|
|
tkopan1@yahoo.com wrote:
| Quote: | WHile I do not dispute the work of these learned researchers, I have a
hard time with the "genetic predisposition" aspect of this. While
certain types of high refractice error of all types has been shown to
be hereditary, vision, being a learned response, changes with the
amount of stress the visual system can handle.
Without trying to be racist or bigoted, we see a alot of high myopia in
the asian populations. These people, as a whole, have different view
of education and instill in their children the need to strive for
excellence. The Indian culture (from India) is much the same way in
the educated segment of their population.
|
your own experience as you relate above for myopia in indian and asian
populations is actually consistent with the idea of genetic
predisposition that you say you have a hard time with.
| Quote: | Once you use up your ability to absorb visual stress (i.e. reading and
CRT use) after doing this task for hours at a time, your ciliary muscle
'cramps up' causing a blur at far which initially clears, but later can
become permanent by causing elongation of the eyeball which is, by
definition, myopia.
|
what evidence is there that accommodative spasm/excess leads to axial
elongation?
| Quote: | This is why so many functionally/developmentally
trained optometrists apply reading lenses to young people. In some
cases, the child's eye is not ready to absorb these kinds of stresses
at such an early age. In Russia, I understand that learning to read is
delayed from 1-3 years. For this reason and they see less
nearsightedness accordingly.
This is what I was taught and how I have apporached this problem for
over 30 years with my patients. When you are right 9/10 of the time,
it is hard to chuck it all and start thinking exclusively genetics.
--Dr. Tom
retinula@hotmail.com wrote:
Hello all,
here is an interesting and highly speculative article that I was
alerted to by dr. judy. I believe someone posting here a month or two
ago gave reference to this theory but a link was never posted.
perhaps, after reading this, many of the people who are so frustrated
about their myopia might consider it in a different light.
retinula
============
W. Mak, M.W.M. Kwan, T.S. Cheng, K.H. Chan, R.T.F. Cheung and S.L. Ho
Department of Medicine, Queen Mary Hospital, University of Hong Kong,
4/F, Professorial Block, 102 Pokfulam Road, Hong Kong, PR China
Medical Hypotheses 2006 vol. 66(6) Pages 1209-1215
Myopia as a latent phenotype of a pleiotropic gene positively selected
for facilitating neurocognitive development, and the effects of
environmental factors in its expression
Myopia has become an almost pandemic problem in many populations.
There are compelling evidence to suggest that myopia is a hereditary
condition. However, myopia would constitute a definite selection
disadvantage during most stages of human evolution, which is
incompatible with its moderate to high prevalence in most modern
populations. The rapid upsurge of myopia over just a few decades also
implies that its inheritance does not follow any of the usual
patterns, and environmental factors may have an important role in
precipitating its occurrence in those who are genetically predisposed.
Previous studies showed that myopes were, on average, more intelligent
than non-myopes, and this association had been attributed to a
biological link between eye growth and brain development. We propose a
pleiotropic genetic model to explain the atypical epidemiologic and
inheritance pattern of myopia and its relationship with neurocognitive
development. This pleiotropic gene was positively selected for its
facilitation of human intelligence. The myopic component is a latent
phenotype; myopia will not be expressed unless some novel external
factors are encountered (i.e. a "quirk" phenomenon). Therefore, the
myopic component was selectively neutral in our ancestral environment.
The net gain in Darwinian fitness enables the pleiotropic gene to
attain a high frequency in the human population, as reflected by our
current prevalence of myopia.
Shortened Link:
http://tinyurl.com/kusft |
|
|
| Back to top |
|
|
LarryDoc
medicine forum Guru Wannabe
Joined: 29 Apr 2005
Posts: 262
|
| Posted: Thu May 11, 2006 6:15 pm Post subject:
Re: Myopia a side-effect of an Intelligence Gene?
|
|
|
I think for those readers who have not already bought into this, there
are two key points to reflect on here:
In article <FEv8g.2700$u4.357@newsread1.news.pas.earthlink.net>,
"Mike Tyner" <mtyner@mindspring.com> wrote:
| Quote: | I don't know what "stresses" you mean. If "stress" is accommodation, then
there are lots of people who carry around a huge load of habitual
accommodation and they aren't more prone to nearsightedness. If "stress" is
something else then please be more specific.
|
The uncorrected or undercorrected hyperopes (farsighted) are that group
of constantly stressed (at least accomodation -wise) people.
| Quote: |
In Russia, I understand that learning to read is
delayed from 1-3 years. For this reason and they see less
nearsightedness accordingly.
We agree that myopia is associated with more time spent reading. Myopia is
an adaptive response to near work. But easing accommodation with special
lenses does not significantly alter that correlation.
|
The other key point. Tested clinically for decades. Wish it worked, but
hope and prayers don't affect change here.
| Quote: |
This is what I was taught and how I have apporached this problem for
over 30 years with my patients. When you are right 9/10 of the time,
it is hard to chuck it all and start thinking exclusively genetics.
Makes one wonder why the effect doesn't show up in controlled studies.
-MT
|
Ah, science.
LB, O.D. |
|
| Back to top |
|
|
Neil Brooks
medicine forum Guru
Joined: 24 Mar 2005
Posts: 1148
|
| Posted: Thu May 11, 2006 6:22 pm Post subject:
Re: Myopia a side-effect of an Intelligence Gene?
|
|
|
Mike Tyner wrote:
| Quote: | I don't know what "stresses" you mean. If "stress" is accommodation,
then
there are lots of people who carry around a huge load of habitual
accommodation and they aren't more prone to nearsightedness. If
"stress" is
something else then please be more specific.
|
LarryDoc wrote:
| Quote: | The uncorrected or undercorrected hyperopes (farsighted) are that group
of constantly stressed (at least accomodation -wise) people.
|
As usual, I like to cite myself as a wonderful anecdotal example:
Despite YEARS of disability due to chronic eye pain, eventually diagnosed
(by me) as severe ciliary spasm (call that "accommodative stress?"),
eventually diagnosed and "relieved" via MONTHS of nightly cycloplegic
use--when the spasm finally "broke," eliciting nearly three diopters of
formerly non-existent accommodative amplitudes--it turns out that my
underlying cycloplegic refraction HAD NOT CHANGED since I was an infant (I
gathered all the records).
Still the same high-hyperopic, moderate astigmatic Rx. IF ciliary
stress/accommodative tension/call it what you will will elongate the eye
.... how come it didn't elongate mine ... after YEARS of EXTREME stress? I
was waiting. I would have welcomed it.
But it didn't.
Outlier or not ... they have to be addressed, no? |
|
| Back to top |
|
|
retinula@hotmail.com
medicine forum beginner
Joined: 14 Nov 2005
Posts: 44
|
| Posted: Thu May 11, 2006 8:44 pm Post subject:
Re: Myopia a side-effect of an Intelligence Gene?
|
|
|
exactly. the only refractive change that happens to adult hyperopes is
that they manifest even more hyperopia over time. kinda shoots the
"accommodative stress induces myopia" theory in the foot. never
convinced otis though. |
|
| Back to top |
|
|
Google
|
|
| Back to top |
|
|
|
|
The time now is Thu Jan 08, 2009 2:38 am | All times are GMT
|
|
Mobile Phones | Personal Car Finance | Dirty Dozen Brass Band | Payday Loan | Kung fu for a healthy you
|
|
Copyright © 2004-2005 DeniX Solutions SRL
|
|
Other DeniX Solutions sites:
electronics forum,
Science forum
Unix/Linux blog
Unix/Linux documentation
Unix/Linux forums
|
Powered by phpBB © 2001, 2005 phpBB Group
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
Forum index
»
Medicine forums
»
vision
