PosChang.txt

Subject: Proving that "protective" positive state can be
developed in the natural eye.


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Excerpt from:

The Eye in its Relation to Health

By Chalmer Prentice, M.D.

Chicago, A.C. McClurg & Company, 1895

Transcription (c) A. Wik, 2004


Case 2. Partly manifest; D. A., age forty; Dr. Stanley of
Brantford, Ont., says this case has been under his
observation for upwards of four years;

[Comment: The reasons why Prentice took the following plus-lens
steps are not important. What is important is the proof
that an eye with a positive lens on it changes its
refractive state in a positive direction as proven by
the following sequence. From primate studies,
refractive states from zero to +2.0 diopters are
completely normal. "Hyperopia" is a positive refractive
state of the natural eye -- within reason. OSB]

No hyperopia was found by dropping a two grain solution of
atropine into the eyes twice a day for one week; then increasing
to four grains to the ounce, it was used for three days, and on
examining the eyes again I still found no indication of
hypermetropia.

[Comment: Historically, a refractive state of exactly zero is
called "emmetropia". Prentice is using a cycloplegic to
make this measurement -- which is considered standard
around the world. OSB]

Vision without the glasses was twenty-twentieths or normal.
I prescribved a +1 D glass for outdoor use, which gave
twenty-fiftieths of vision at twenty feet. For house, reading,
writing and all close purposes, I prescribed a +4 D, which was +1
D more than an absolute suspension of accommodation at thirteen
inches.

[Comment: A +4 diopter lens will move the "near" environment out
to "infinity" or beyond -- thus simulating living in the
"wild". OSB]

This rendered the patient artificially myopic. At the
expiration of three months, through the +1 D glasses at twenty
feet, vision was twenty-twentieths. On removing the glasses,
vision was also normal, but on returning them to the eyes again,
the vision through the glasses was now reduced to
twenty-thirtieths, but in half an hour it was again
twenty-twentiehts or normal.

I now increased the power of both pairs of glasses +0.75 of a
dioptre, which again gave twenty-fiftieths of vision at a
distance, and the glasses for near use about the same amount of
artificial myopia that the first pair of reading glasses gave.

At the expiration of six months more, vision under the +1.75
D, at twenty feet, was normal.

[Comment: Normal means 20/20 in this context. OSB]

On removing these glasses, it now required some five minutes
for normal vision to take place, indicating that the reduction of
ciliary innervation was become somewhat fixed.

[Comment: The eye has a positive refractive state of +1.75
diopters, which is "high-normal". Primates and persons
can and do have 20/20 with the positive status. OSB]

The glasses were continued, as well as the above modus
operandi, for a period of one year, since which time the patient
has been wearing +2.75 for all general purposes. With these
glasses vision is twenty-twentieths at all distances...

[Comment: Prentice has created a positive refractive state of
+2.75 diopters, bascially PROVING that the human-primate
eye performs exactly the way the the adolescent primate
eye behaves. OSB]

...but for the purpose of resting the accommodation, a +5 D
is frequently resorted to for long and continued close work.


[Comment: It is not clear exactly WHY Prentice made this woman's
refractive state "positive" but his actions do prove the
point. Remember, a positive refractive state of +1.0
diopter is considered VERY VALUABLE for midshipmen
entering a four year college. OSB]