Author Topic: why does a plus lens prevent myopia ?  (Read 2765 times)

Offline rtdfgdfgdfgdfg

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why does a plus lens prevent myopia ?
« on: August 10, 2015, 12:21:43 PM »
if you do up close work 16 hours a day,

why does a plus lens prevent myopia ?

does the plus lens trick the eye muscle into thinking you are looking into the distance ?

Offline VisionRecovery

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Re: why does a plus lens prevent myopia ?
« Reply #1 on: August 10, 2015, 02:05:23 PM »
According to high school physics, convex (plus) lenses converge light to create enlarged virtual images (increased image distance) if the object is closer than the focal point.

Also, concave (minus) lenses diverge light to create diminished virtual images (decreased image distance) of objects at every distance.

However, without prism, using plus lenses might confuse your eyes because they are still converged.
« Last Edit: August 10, 2015, 02:07:43 PM by VisionRecovery »

Offline OtisBrown

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Re: why does a plus lens prevent myopia ?
« Reply #2 on: August 10, 2015, 03:36:40 PM »
Hi Rtd,

Otis>  I wonder what would happen to my natural eyes  ....

Rtd> .... if you do up close work 16 hours a day?

That is a good scientific question, if you re-organize it.  Ask it this way,
"What would happen if I forced the normal primate eye, into "long-term near", and kept them for 16 hours a day, reading at 13 inches, or -3 diopters"?

Let us say that have "emmetropia" at the start of this scientific test.  (emmetropia = exactly 0.0 diopters).

Now, what do you believe will happen?  There are only two results possible.

1) The refractive state of these normal eyes, will not change in a negative direction, i.e., new refractive state = -3/4 diopters after six months, or

2) The official medical theory and concept.  No, the refractive state of these eyes, kept in a -2 diopter environment, and after six
months the refractive state of the test and control groups would be identical.  (i.e., all refractive states are genetic,
so there is no possibility, that doing reading at -3 diopters would result in the natural eye taking on "negative state", or
becoming "nearsighted".  (Normal eye - with negative status.)

Which do you think would happen, objectively? #1 or #2?

You truly can not answer any other questions - until you choose the right answer here.


if you do up close work 16 hours a day,

why does a plus lens prevent myopia ?

does the plus lens trick the eye muscle into thinking you are looking into the distance ?
« Last Edit: August 10, 2015, 03:41:15 PM by OtisBrown »

Offline rtdfgdfgdfgdfg

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Re: why does a plus lens prevent myopia ?
« Reply #3 on: August 10, 2015, 05:30:31 PM »
your wording is slightly confusing

but I believe #1, it will change in a negative direction, if you forced someone to read at 13 inches , 16 hours a day

« Last Edit: August 10, 2015, 05:37:20 PM by rtdfgdfgdfgdfg »

Offline OtisBrown

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Re: why does a plus lens prevent myopia ?
« Reply #4 on: August 10, 2015, 07:51:06 PM »
Hi Rtd,

LOGICAL STEP ONE:

I also believe that #1 is the correct answer.  People in medicine, believe that #2 is the correct answer.  But
that is the difference between objective science, and "servicing" a great mass of humanity, with a minus lens.

It should be obvious, that if you do not want your "emmetropic" eye, to change its refractive STATE in a
negative direction, you should not spend 16 hours a day, reading at -3 diopters, or 13 inches.

LOGICAL STEP TWO:

OK, so you read at -3 diopters (13 inches), for six months.  Now your refractive STATE, is -2.0 diopters after six months of this.

So you go to an OD who, checks you Snellen (yes 20/100), and uses a "trial lens", and sees that a -2 diopter, now
gives you 20/20.

So you are prescribed a -2 diopters for your normal eyes (with self-induced negative status).  You are told that,
"no one knows why your  refractive state is at -2 diopters, but you NEED a strong minus lens."

Now you go back to reading 16 hours a day at 13 inches (-3 diopters).  But because you are wearing a -2 diopter lens,
while doing this reading, your actual "environment", is -3 D + (-2 D) = -5 diopters.

Now you do this for six months, and your eye again changes by -2 diopters, and because of this natural process,
you find your refraction is now -4 diopters.

You go back to the optometrist, who finds that it now take a -4 diopter lens to give you 20/20, so your "prescription",
is now -4 diopters.

The OD tells you that,  1) Long-term close work (at -3 diopters), does not create negative status, and 2) The combination
of the first -2 D, and full time wear, and close work at -5 diopters, is NOT THE REASON YOUR REFRACTIVE STATE IS OBJECTIVELY MEASURED AT -4 DIOPTERS.

You are told that it is "... all because of your 'bad heredity' ".

My question is this - do you believe him?
« Last Edit: August 11, 2015, 03:34:32 AM by OtisBrown »

Offline rtdfgdfgdfgdfg

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Re: why does a plus lens prevent myopia ?
« Reply #5 on: August 11, 2015, 10:49:29 AM »
no

I don't believe him

the person in that example should have used glasses, only as strong as he needs them for the close up work

the message is, don't get any stronger than you need.

so if I only needed -1 for close up work, but I use -5 all day to look at mountains,

using -5 "up close"  is what kills your eyes

for looking at mountains, it is acceptable, but not ideal ?


wearing -2 lenses, but reading at -3 length (13 inches), will destroy the eyes



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so to summarise , if I am -5, and I look into the distance at the moon, this in theory, is safe.

but doing "up close" work that would only need a -1 lens,    but wearing -5 glasses  , is totally dangerous.

Up close  :  either no glasses at all or the plus prevention , or only for how strong you need them for doing "up close"

every different situation in life, in theory, needs a different lens, or your eyes get worse, as everyone's do
« Last Edit: August 11, 2015, 09:31:33 PM by rtdfgdfgdfgdfg »