The Correct Answers

Quote:

Sure, Mike, here are the t-tests you requested.

I assume you mean student's "t" for small samples,
and "z" for large sample Gaussian distributions.

Dr. Francis Young spent a lot if time collecting
these facts concerning the dynamic behavior
of the fundamental eye.

But you never understand that at all.
Ya get my drift, partner?

Otis

++++++++

[The reference studies for the primates and Eskimos are at
the end of this page. **]

FIRST-YEAR HONG KONG UNIVERSITY STUDENTS 87.5 % MYOPIC

o Goh and Lam (Goh, W.S. and Lam, C.S., "Changes in refractive
trends and optical components of Hong Kong Chinese aged 19-39
years," Ophthal. Physiol. Opt., 14:378-382, 1994) found that
in 2000 first-year students at the University of Hong Kong,
the prevalence of myopia was 87.5%.

******************

MYOPIA PREVALENCE IS ALWAYS HIGHER THAN 92 PERCENT
FOR TAIWAN MEDICAL STUDENTS

o Lin et al (Lin, L.K., Shih, Y.F., Lee, Y.C., Hung, P.T., and
Hou, P.K., " Changes in ocular refraction and its components
among medical students - a 5-year longitudinal study", Optom.
Vis. Sci., 73:495-498, 1996) found that in a study of 345
National Taiwan University medical students, the myopia
prevalence increased from 92.8% to 95.8% over the five year
period.

******************

OPTOMETRY STUDENTS 72 PERCENT MYOPIC

o Lam and Yap (Lam, C.S. and Yap, M. "Ocular dimensions and
refraction in Chinese Orientals", Proc. Int. Soc. Eye Res.,
6:121, 1990) found that in a group of optometry students at
The Hong Kong Polytechnic University, the prevalence of myopia
was 75% in females and 69% in males.

******************

70 PERCENT MYOPIC AT AGES 16 TO 17 YEARS OLD

o Regarding the prevalence of myopia in Asian countries, Lam and
Goh (Lam, C.S. and Goh, W.S., "The incidence of refractive
errors among schoolchildren in Hong Kong in relationship with
the optical components", Clin. Exp. Optom., 74:97-103, 1991)
found that in 383 school children from ages 6 to 17 years, the
prevalence of myopia increased from 30% at ages 6-7 years, to
70% at ages 16-17 years.

******************

December 6, 2000

By Liu Shao-hua
Staff reporter
Taipei Times

Subject: Myopia Increases Among Children

One of every five children in the first grade in Taiwan's
elementary schools is myopic (nearsighted). The proportion of
myopics in this group has increased from 12.1 percent in 1995 to
20.4 percent this year, according to the results of a survey
released by the Department of Health yesterday.

The results also show that 60.7 percent of sixth graders in
elementary schools, 80.7 percent of third graders in junior high
schools, and 84.2 percent of third graders in senior high schools
suffer from myopia. In addition, the number of seriously myopic
children is also on the rise. The proportion of seriously myopic
children among sixth graders in elementary schools has increased
from 2 percent five years ago to 2.4 percent this year.

Serious myopia is defined as exceeding 600 degrees (6
diopters). Anything over 25 degrees (0.25 diopters) is myopia.
Normal eyesight is zero degrees.

"We appeal for reductions to children's work load in schools
and the amelioration of visual environments in daily life," said
Chen Tzay-jinn, director-general of the health promotion bureau,
under the health department.

The survey was conducted by the department, in cooperation
with National Taiwan University and its hospital, and involved a
sample of 12,000 students from four million students between the
ages of 7 and 18 nationwide. Myopia has been on the increase in
Taiwan ever since the first myopia survey in 1983. The department
manages the survey every four or five years.

The growth of nearsightedness among young children is thought
to result from learning to read very young and using computers
very young, Chen pointed out.

Last year, the department and the Ministry of Education
delivered official documents to kindergartens nationwide demanding
that children not be taught to read or use computers too early.
"But many teachers and parents protested against this appeal,"
said the department officials. "They questioned exactly what they
were permitted to teach if reading was not allowed."

"We do hope that parents and teachers can heighten their
awareness of myopia and understand that early learning does not
guarantee students' performance in the future, but it does bear a
strong correlation to defects in vision," Chen said. The
department also appealed for children under the age of 10 not to
be taught how to use computers.

Senior high school students suffer the highest rates of
nearsightedness, at over 84 percent. "It reached a plateau five
years ago and has not changed this year. But their myopia has
become more serious," Chen said. According to the survey, 20
percent of third graders in senior high schools are seriously
nearsighted.

Many people thought operations could cure myopia. "But the
superficial improvement of vision does not better the health of
the eye. More importantly, it might reduce people's awareness of
other problems associated with nearsightedness, apart from visual
ones," said Lin Lung-kuang, ophthalmology professor at National
Taiwan University. "Myopia cannot be cured. We have to prevent
children from becoming nearsighted. Don't let them use their
vision too early," Lin urged.

Because of the public's lack of awareness of myopia, the
department estimated its prevalence would continue to grow.
"Singapore resembles Taiwan in many respects and the extent of its
myopia problem might serve as a warning for us," Chen said.

__________________________________________________________

** Below are the 5 sources of the statistics for the
behavior of the natural primate and Eskimo eye.

1. "Visual Refractive Errors of Wild and Laboratory Monkeys", Francis
A. Young, Pullman, Washington, E.E.N.T. Digest, Volume
27, Pages 55-71, August 1965

Wild Primate eyes:

N = 598 Eyes

Mean = 0.63 Diopters

Standard Deviation = 0.72 diopters

What this means:

68 percent have refractive states from -.1 diopters to +1.35
diopters

96 percent will have refractive states from -0.8 diopters to
+2.07 diopters.

"...Animals less than 12 years old with refractive errors
between +2.0 and -0.5 diopters, normal retina and no obvious
visual difficulties are likely to have 20/20 acuity at near and
far at better-than the 5 % level of confidence.

Of some 26 rhesus monkeys within with in this range of
refractive errors ALL had 20/15 or 20/20 visual acuity. Animals
with refractive errors greater-than +2.0 diopters may have 20/20
acuity at far but not at near.

Animals with refractive errors which are more minus than -0.5
diopters will not have 20/20 acuity at far but may have it at
near."

"...Thus individuals with 20/20 acuity may have refractive
errors ranging from 0 to +3 diopters."

Francis A. Young

*****************************************

2. "Ocular Biometry of Eskimo Families", Francis A. Young, George
A. Leary, Primate Research Center, Washington State
University, Pullman, Washington, Diagnostica Ultrasonica
in Ophthalmologia, Paris, Centre National d'Ophthalmologie
des Quinze-vingts, 1973

What is the range of refractive STATES of the natural human
eye -- that have not been profoundly "affected" by 12 to 16 years
in school?

Data taken from:

"The Transmission of Refractive Errors within Eskimo
Families", 1969

Francis Young
George Leary
William Baldwin
Donald West

and

Roy Box
Eugene Harris
Curtis Johnson

Refractive STATES from age 36 to 65:

N = 143 Eskimos

Mean = +1.8 Diopters average

Sigma = 1.27 Diopters

What this data tells us about the 20/20 eye -- using a normal
distribution:

68 percent are positive:

+0.68 diopters to +3.15 diopters

Or no myopia in that percentage.

96 percent between these values:

-0.6 diopters to +4.4 diopters

It is possible to have 20/20 and a retinoscope measurement of
-0.6 diopters.

The published measured values were from

-1.95 diopters to +5.89 Diopters.

There was one Eskimo with a refractive state greater than
-1.0 diopters.

Or, 1/143 = 0.6 percent were significantly myopic.

This result compares with the "educated" Eskimos (younger)
that show average myopia of -2.07 diopters, and 87 percent were
classed as myopic, with approximately 70 percent more myopic that
-1 diopters.

Additional Remarks:

These are the indications that the refractive STATE of the
natural eye simply follows its average visual environment -- as a
fundamental process.

While we have certainly "changed" in our "habits" over the
last 200 years, to suggest that our eyes do not change with change
in average visual environment is simply a failure of concept.

I certainly agree with the "intellectual" difficulties of
plus-prevention at the threshold.

But, I believe that we must understand this issue as an
"engineering trade-off".

By this I mean that a person who has a broad perspective on
these issues can wisely accept the need for systematic use of the
plus, and keep his visual acuity as always the required DMV test.

Or, in other words, progress is only possible with change.
Those people who will attempt to stop change, will also prevent
progress.

I would rather begin the use of the preventive-plus at a
refractive STATE of zero, or slightly negative, and keep my
distant vision in the positive range as per these Eskimo eyes --
than to develop stair case myopia from that long-term "near"
environment -- compounded by an excessively strong minus lens.

Most people never "see" these statistics.
...

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