Dear Prevention-minded scientific friends,

    When I suggested that we use a "plus" to keep your vision
clear through the school years -- it was because of the scientific
facts.

    And also because of Jake Raphaelson's statement about "The
Printer's Son".

    Prevention is not easy at all.  And most prefer neglect -- to
aggressive plus use.

    But here are the refractive STATES of the natural eye, from
one month old -- to adolescent primates living in the "wild".

    Children will now have the opportunity to "prevent" with
the plus -- same as Steve Leung helping his own children.

    There is nothing "easy" about any of this -- but
it beats getting stair-case myopia from an over-prescribed
minus.

    Otie

+++++++++++

    What are the refractive STATES of all fundamental eyes one
month after birth?

    The term "refractive ERROR" has a deadly effect in
understanding the dynamic behavior of the natural eye.

    I strongly suggest a "transition" to using the un-biased term
refractive-State, to avoid any confusion about respecting the eye
as a dynamic system.

    Below is the characterization of the refractive STATES
(absolutely normal) at the age of one month.

    Data taken from:

_____________________________________

Title: "Spectacle lenses alter eye growth and the refractive
status of Young monkeys"

Li-Fang Hung, (1) M.L.J. Crawford (2) & Earl L. Smith (1)

(1) Correspondence should be addressed to Earl L. Smith.

(2) University of Houston, College of Optometry, Houston, TX
77204

(1) University of Texas, Graduate School of Biomedical
Sciences, Sensory Science Center, Houston Texas 77030

    Abstract:    The influence of visual experience on ocular
development in higher primates is not well understood.    To
investigate the possible role of defocus in regulating ocular
growth, spectacle lenses were used to optically simulate
refractive anomalies in young monkeys (for example, myopia or
nearsightedness).  Both positive and negative lenses produced
compensating ocular growth that reduced the lens-induced
refractive errors and, at least for low lens powers (3 diopters)
minimized any refractive-error differences between the two eyes.
These results indicate that the developing primate visual system
can detect the presence of refractive anomalies and alter each
eye's growth to eliminate these refractive errors.  Moreover,
these results support the hypothesis that spectacle lenses can
alter the eye development in young children.

______________________________

    My Commentary:

    I will summarize these results -- in terms of measured
refractive STATE of the natural eye versus a substantial change in
visual-environment.

    11 monkeys were used in this experiment.

    The issue is the dynamic behavior of the natural eye -- and
how to establish it by direct measurements.

    The monkeys were:

    Lens power on right eye.  Left eye is zero diopters

    Name - Lens - Eye -- State at one month

    HT2 0 D (Right) Control 4.5 D

    0 D (Left) 4.5 D

    K1 +6 D (Right) 5 D

    0 D (Left) 5 D

    ME +6 D (Right) 4 D

    0 D (Left) 4 D

    NT +3 D (Right) 5.5 D

    0 D (Left) 5.5 D

    HA +3 D (Right) 4 D

    0 D (Left) 4 D

    HT3 +3 D (Right) 2.5 D

    0 D (Left) 3 D

    NO -3 D (Right) 4 D

    0 D (Left) 4 D

    DE -3 D (Right) 8 D

    0 D (Left) 6 D

    HT1 -3 D (Right) 3.5 D

    0 D (Left) 3.5 D

    DI -6 D (Right) 2 D

    0 D (Left) 2 D

    QU -6 D (Right) 5 D

    0 D (Left) 5 D

    (The monkeys were maintained with these lenses for 72 to 113
days.  The result was that the refractive STATE "followed" the
applied lens.  i.e., the eye is dynamic with respect to the
applied lens.  This "following" process is normal and essential.
OSB)

    The method of measurement of refractive STATE:

    The refractive status was done by retinoscopy.

    To make these measurements, cycloplegia was induced by the
topical application of tropicamide (1%, 2 drops) and the were
anaesthetized.

    Measurements were obtained at the onset of the lens-rearing
procedures and typically every 2 weeks thereafter.

___________________________________________

    The average of these values was:

    mean = 4.3

    The standard deviation (Sigma)

    SD = 1.3

    There was nothing "wrong" with these eyes.

    The 2-Sigma numbers are +6.9 diopters and + 1.7 diopters.

    This means that 96 percent of the refractive STATES of
primates (human and rhesus) will fall between these numbers.

    The 3-Sigma (99.7 percent) of the normal refractive STATES
will lie between +0.4 diopters to + 8.2 diopters.

    For all practical purposes, there are no "myopic" primates at
age 1 month.

    +++++++++++++++++++++++++++++

    Why are these "recognition" important?

    Because when primates (and humans) are raised "in the wild",
their refractive STATES have the following values:

    Mean +0.7 diopters

    Sigma = 0.7 diopters

    Or, given the 2-Sigma spread, 96 percent of primates in the
wild would have refractive STATES from -0.7 to +2.1 diopters.  It
must be understood that it is possible to have 20/20 vision and
measure a -0.7 diopter refractive STATE.

    Higher positive refractive STATES have 20/20 vision at this
age to post adolescent.

    Thus only the negative "tail" would be "nearsighted", and
that would be 2 percent.

    Otis