Author Topic: changes in eye size?  (Read 4916 times)

Offline OtisBrown

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Re: changes in eye size?
« Reply #15 on: February 06, 2014, 04:05:14 AM »

Hi Sam,

There was a drastic mistake, or assumption made a long time ago.  What is always measured it a relative refractive state.  I it is almost impossible to accurately measure a "length".  So let us talk about actual measurements - not about "conjecture about length".  Here again is what the minus lens does to all natural eyes.

http://www.ocf.berkeley.edu/~wildsoet/images/neg_lens_induce_myopia.swf

What is measured, is a refractive STATE, that changes objectively, when a minus 3 is applied.  What is INFERRED, is that the "length changed". Maybe it did - and maybe it did not. But why does that matter?  I doubt that you will find any pure-science that will dispute this image of the actual normal eye.  But I would emphasize that this is "speeded up", and that the change of the natural eye is VERY SLOW.

If you accept this picture from science, then, if worn when your refractive state is -3/4 diopters, you can get a change of +1 diopter, that will slowly get you back to naked-eye 20/20. That is what Todd did.


so if a children with a refractive state of  say +2.5D is given a +2.5D plus lenses, he gets more and more farsighted and his eyes get....shorter and shorter?

i have never though of this before, so it does seem very likely that the eye shape does change. and so axial myopia, deemed as "incurable", "impossible to reverse" may actually be reversible although very very slowly.

If a child is +2.5D and he wears a +2.5D plus lens and does close work all day. Does his positive refractive become even more positive at the same rate compared to that of a myopic child wearing a minus lens (becoming more negative)?

Offline Myoctim

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Re: changes in eye size?
« Reply #16 on: February 06, 2014, 11:59:51 AM »
so if a children with a refractive state of  say +2.5D is given a +2.5D plus lenses, he gets more and more farsighted and his eyes get....shorter and shorter?

There seems to be a genetic factor because a person although when being emmetropic in central vision also could be myopic or hyperopic in peripheral vision.

According to a study on pilot students when doing nearwork for education those with peripheral hyperopia had been much more prone to a myopic shift compared to those with emmetropic or myopic peripheral refraction.

As mentioned here some time ago by Tom Lu it even should be possible for folks with peripheral myopia getting hyperopic by reading.
Maybe To Lu can explain more about that?


Offline OtisBrown

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Re: changes in eye size?
« Reply #17 on: February 06, 2014, 12:53:40 PM »
Hi Myoctim,

You indeed have expert knowledge.  Could you post the reference to this paper?

Thanks,



so if a children with a refractive state of  say +2.5D is given a +2.5D plus lenses, he gets more and more farsighted and his eyes get....shorter and shorter?

There seems to be a genetic factor because a person although when being emmetropic in central vision also could be myopic or hyperopic in peripheral vision.

According to a study on pilot students when doing nearwork for education those with peripheral hyperopia had been much more prone to a myopic shift compared to those with emmetropic or myopic peripheral refraction.

As mentioned here some time ago by Tom Lu it even should be possible for folks with peripheral myopia getting hyperopic by reading.
Maybe To Lu can explain more about that?

Offline Alex_Myopic

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Re: changes in eye size?
« Reply #18 on: February 06, 2014, 01:35:25 PM »
But even perfect peripheral vision it is only about 20/70!

Offline Myoctim

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Re: changes in eye size?
« Reply #19 on: February 08, 2014, 02:32:02 PM »
Hi Myoctim,
Could you post the reference to this paper?
Thanks,


Hi Otis,

here is a link about the Hoogerheide study, Peripheral refraction and  the development of refractive errors

http://onlinelibrary.wiley.com/doi/10.1111/j.1475-1313.2010.00746.x/full


Offline CapitalPrince

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Re: changes in eye size?
« Reply #20 on: March 11, 2014, 07:12:23 AM »
My eyes took 3 years of total abuse from high school reading at 20cm for 10+ hours a day. One day i realized i could do this "weird" thing with my eyelids and my eyes "felt" longer, Also I began to feel my eyes don't really converge, like they are looking at the space inbetween the image rather than on it. Also i begin to experience these weird things as i blinked. I saw my vision going down slowly over the years, but never really cared until it affected my life.
so yes eye elongation/axial myopia is real

Offline OtisBrown

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Re: changes in eye size?
« Reply #21 on: March 11, 2014, 07:43:14 AM »
Hi Myoctim,

Thanks for the paper - I sent it to Todd for his review.

Best,

Hi Myoctim,
Could you post the reference to this paper?
Thanks,


Hi Otis,

here is a link about the Hoogerheide study, Peripheral refraction and  the development of refractive errors

http://onlinelibrary.wiley.com/doi/10.1111/j.1475-1313.2010.00746.x/full

Offline CapitalPrince

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Re: changes in eye size?
« Reply #22 on: March 11, 2014, 08:56:16 AM »
frauenfeld also talked about peripheral vision here.
http://frauenfeldclinic.com/depression-anxiety-might-want-avoid-frames/

conclusion: peripheral vision is important to take into consideration for any refractive errors.