Real Eyecare
What is The Cause of Myopia?
New Theory:  (Theory B)
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The Cause of Myopia
Myopia is caused by prolonged close work.
Our eyes are designed for distant viewing.  They are at rest (i.e. completely relax) when looking at distant objects.  (Figure 1)
When a distant object is moved closer, light rays from that object will come to a focus behind the retina, resulting in a blurred image, if the eye loses its focusing ability, which happens to older people who have presbyopia.  (Figure 2)
For people without presbyopia, when viewing a close object, the ciliary muscle contracts automatically and instantly causing the lens to become thicker in order to bring the light rays to a focus on the retina.  (Figure 3)
When we do prolonged close work, the ciliary muscle which is under a constant state of stress develops a spasm.  When this happens, the lens fails to return to its original thin shape even when accomodation is relaxed (viewing a distant object).  The light from a distant object is brought to a focus in front of the retina resulting in a very slightly blurred image.  (Figure 4).   
The eye can no longer see 6 meter (20 feet) or more clearly.  The eye can only see clearly up to 2 meter (6.6 feet) as shown in Figure 5.  Anything beyond is very slightly blurred.
We continue to do prolonged close work.  (Figure 3)
Ciliary muscle spasm get worse which makes the lens thicker.  A distant object become blurrier (Figure 6) than before.
The eye can now only see clearly up to 1 meter (3.3 feet) as shown in Figure 7.  Anything beyond is much blurrier than before.
The larger versions of a 1D myopic eye are shown below.
We continue to do prolonged close work.  (Figure 3 Large)
After ciliary spasm has developed, the continuous contraction of the ciliary muscle which makes the lens thicker causes an increase in the pressure in the vitreous chamber.  This pressure in the eye (intraocular pressure) causes an increase in size of the vitreous chamber (i.e. the eye elongates) resulting in a more myopic eye.  (Figure 8 Large).   
After the eye elongates, it does not need to work as hard.  The eye can now do the close work with a lot less stress.  (Figure 9 Large)
However, the eye can no longer see clearly in the distance.  (Figure 10 Large)  It can only see clearly up to 0.5 meter (20 inches).
If we do not do prolonged close work at a closer distant such as reading with the nose on the book, this is pretty much how bad our myopia is going to progress.
Without the use of the prescription glasses (minus lens), myopia seldom progresses beyond -3.00D.  It will normally stay below -2.00D which most people can live with.  This is indeed what happens to indigenous or primitive people and people in underdeveloped countries who also do some sort of close work such as knitting, tool making, etc. who, fortunately, have no access to the prescription glasses.  This is also what happens to the people who refuse to wear the prescription glasses or who do not wear the prescription glasses all the time such as for prolonged close work in developed countries today.
Proof1
High Myopia does not normally occur without the use of the prescription glasses(minus lens).
Proof2
For most people in developed countries, when we cannot see clearly in the distance, we simply go to the eye doctor's to get a pair of  prescription glasses so that we can see clearly in the distance.
The prescription glasses "seem" to solve the problem.  The minus lens which bends the light away from the center does the trick by bringing the light from a distant object to a focus on the retina resulting in a clear image.  (Figure 11 Large)
The Real Problem Begins......
We wear the prescription glasses all the time as told by the eye doctor.  The eye doctor also tells us that the glasses have no side effect whatsoever.
We continue to do prolonged close work, wearing the prescription glasses this time.
Remember, close work without glasses does not require much effort from the myopic eye as shown in Figure 9 Large.
However, close work with the prescription glasses requires a lot of effort from the eye.  If the eye loses its power of accommodation which occurs with aging, the light from a close object which is bent away from the center will end up behind the retina resulting in a blurred image as shown in Figure 12 Large.  This is indeed what happens to older people.  This is the reason why older myopic people have to remove their glasses to read.  (see Figure 9 Large)  Power of accommodation decreases from 20 Diopter of a six-year-old child to about 2 Diopter of a fifty-year-old adult.
Therefore, when doing close work with the prescription glasses, the eye has to work harder to focus the light from a close object on the retina. (Figure 13 Large)  This is an easy task for young adult and children whose eyes are full of power.  (20D for a 6-year-old child)
After a while, the pressure in the eye causes the eye to elongate resulting in a more myopic eye. (Figure 14 Large)
After the eye elongates, it does not need to work as hard.  The eye can now do the close work with a lot less stress.  (Figure 15 Large)
However, the eye can no longer see clearly in the distance wearing the same pair of prescription glasses.  (Figure 16 Large)
We go to the eye doctor's for the second time.  The eye doctor gives us a pair of stronger prescription glasses so that we can see clearly in the distance again.  (Figure 17 Large)
The Problem Continues......
We wear the prescription glasses all the time as told by the eye doctor.  The eye doctor tells us again that the glasses have no side effect whatsoever.
We continue to do prolonged close work, wearing the new pair of prescription glasses this time.
Remember, close work with the older pair of prescription glasses does not require much effort from the myopic eye.  (Figure 15 Large)
However, close work with the new pair of prescription glasses requires a lot of effort from the eye.  If the eye loses its power of accommodation which occurs with aging, the light from a close object which is bent away from the center will end up behind the retina resulting in a blurred image as shown in Figure 18 Large.
Therefore, when doing close work with the new pair of prescription glasses, the eye has to work harder to focus the light from a close object on the retina. (Figure 19 Large)
After a while, the pressure in the eye causes the eye to elongate resulting in a more myopic eye. (Figure 20 Large)
After the eye elongates, it does not need to work as hard.  The eye can now do the close work with a lot less stress.  (Figure 21 Large)
However, the eye can no longer see clearly in the distance wearing the same pair of prescription glasses.  (Figure 22 Large)
We go to the eye doctor's for the third time.  The eye doctor gives us a pair of stronger prescription glasses so that we can see clearly in the distance again.  (Figure 23 Large)
We wear the prescription glasses all the time as told by the eye doctor.  The eye doctor tells us again that the glasses have no side effect whatsoever.
Nearsighted People's Worst Nightmare.
One day while jogging in the park, suddenly, the retina detaches from the back wall of the eye. (Figure 24 Large)
Our vision is lost forever.
Thanks to The Eye Doctors.
Thanks to the eye doctors who continuously prescribe us with stronger and stronger pair of prescription glasses and tell us to wear it all the time.
Thanks to the eye doctors who, up to this minute, still deny the side effects of wearing the prescription glasses all the time.
Thanks to the eye doctors who, up to this minute, still deny prolonged close work as the major cause of myopia.
Thanks to the eye doctors who refuses to help us with myopia control.
Thanks to the eye doctors who make our eyeball elongate which results in
Retinal Detachment.
The Problem Ends.