Subject:  Vodoo Optometric Statistics

Re: Response to William Stacy's request to report scientific
   fact accurately concerning the "down" rate for
   children wearing a single-minus lens.

Otis>> It is obvious that the situation is only preventable
      (potentially) -- given the -1/2 dioter per year for children
      wearing a single-minus, as shown in a number of
      published scientific studies.

Stacy> ok so according to this if the kid starts at -1.00 at age
      6:

Stacy> he'd be -2 at age 8

Stacy> -3 at age 10

Stacy> -4 at age 12

Stacy> -5 at age 14

Stacy> -6 at age 16

Stacy> I see that kind of progression in maybe 1% of my patients.
      And I'm talking MANY THOUSANDS OF PATIENTS.

Stacy> Come on, Otis.  YOUR NUMBERS ARE WRONG.    Sorry.    Do some
      real research, and stick to facts, preferably verifiable
      facts.

Stacy> w.  stacy, o.d.

    ________________________

Dear William,

Re: ...and stick to facts, preferably verifiable facts.  Stacy OD

Minus vision lenses:           - 1.23 D increase (2 years)

Progressive lenses with +1.50 add:  - 0.76 D increase (2 years)

Progressive lenses with +2.00 add:  - 0.66 D increase (2 years)

Source:  Leung JT, Brown B.  Progression of myopia in Hong Kong
Chinese schoolchildren is slowed by wearing progressive
lenses.  Optom Vis Sci 1999; 76:346, 354.  Published 10/07/00.

          ______________________

    The -0.6 / diopter-per-year is the AVERAGE of the population
of children wearing a single-minus lens.

    Apparently they did not teach an UNDERSTANDING of statistics
in your optometry school, or you were out-to-lunch during these
scientific statistics courses.    Or Stacy depends on the
public's ignorance of these statistics to make his case
that a minus lens is "perfectly safe".

    Stacy must be living in a statistical "black hole".  or a
profound statistical anomaly.

        _________________________

    Lisa -- Here is the convenient office-myth, or
office-anectdotes -- ODs tell their patients when they become
"concerned" when their children develop stair-case myopia.

    The work of Steve Leung OD, and his use of the plus lens
profoundly disputes Stacy's contention that only 1 percent of
young children show a "downard" change in refractive status when a
minus lens is applied to the eye.  See the statistics below for an
accurate assessment statement of scientific facts.

    Best,

    Otis

         ________________________________

      MYOPIA PREVALENCE IS ALWAYS HIGHER THAN 90 PERCENT
            FOR TAIWAN MEDICAL STUDENTS

Re: 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.

              ******************

1)  In Singapore, the vision of 421,116 males between the ages of
   15 and 25 was examined.  In 1974-84, 26.3% were myopic; in
   1987-91, 43.3% were myopic.  Both the prevalence and severity
   of myopia were higher as the level of education increased.
   The prevalence rate was 15.4% in males with no formal
   education and increased steadily through the education levels
   to reach 65.1% among the university graduates in 1987-91.  The
   authors state that their findings confirm indications from
   other sources that the association between the prevalence and
   severity of myopia and education attainment is real (M.T.
   Tay, K.G.  Au Eong, C.Y.  Ng and M.K.  Lim, "Myopia and
   Educational Attainment in 421,116 Young Singaporean Males,"
   Ann Acad Med Singapore, 1992, Nov;21(6):785-91).

2)  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.

3)  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.

4)  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%.

5)  Lin et al (Lin, L.-K, Chen, C.J., Hung, P.T., and Ko, L.S.,
   "National- wide survey of myopia among schoolchildren in
   Taiwan, Acta Ophthalmol.", 185:29-33, 1988) found that in a
   national survey of children in Taiwan, the prevalence of
   myopia was over 70%.

6)  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.

7)  A recent study in Hong Kong showed what other studies have
   shown - wearing less than a full correction will slow the
   progress of the myopia.  Children selected for the study were
   between the ages of 9 and 12.  All were nearsighted, with 1.00
   to 5.00 D of myopia.  The children were separated into three
   groups.  Each group was given a different type of eyeglasses
   to wear for the two-year period of the study.  The first group
   wore single vision lenses with a full correction; the second
   group wore progressive lenses with a +1.50 add; the third
   group wore progressive lenses with a +2.00 add.  All children
   were examined at 6-month intervals to check the progression of
   their myopia.  Sixty-eight children completed the study.  As
   expected, more undercorrection meant slower myopia
   progression.

Minus vision lenses:           - 1.23 D increase (2 years)
Progressive lenses with +1.50 add:  - 0.76 D increase (2 years)
Progressive lenses with +2.00 add:  - 0.66 D increase (2 years)

Source:  Leung JT, Brown B.  Progression of myopia in Hong Kong
Chinese schoolchildren is slowed by wearing progressive
lenses.  Optom Vis Sci 1999; 76:346, 354.  Published 10/07/00.