--- In Myopiafree2@yahoogroups.com, "Otis S. Brown" <otisbrown@...>
wrote:
>
>
> Dear Judy,
>
> Good -- then you agree with the Bates-Helmholtz
> concept of whole-eye change of refractive
> power-length. As controled by micro-blur
> sensed at the surface of the retina.

There is no Bates-Helmholtz concept. Bates denied the action of the
lens and ascribed all accommodation to axial length changed caused
by extra ocular muscles and his model is inconsistent with the known
large effect of the lens/small effect of axial length. Helmholtz's
model of ciliary body action on the lens is consistent with the very
small axial length contribution as that axial length change can be
easily attributed to contraction of the ciliary muscle as well.

For most purposes, we can "round off" accommodation effect to the
lens as the axial length change is so small. For example, a +6
accommodative change would be due to 5.97D of lens change and 0.03D
of axial length change -- I think we can agree that 5.97 can be
rounded up to 6 and 0.03 can be rounded down to zero. Similarly, a
3D accommodative change is 2.985 lens and 0.015 axial change.

>
> That is the first step of agreeing that
> a population of natural eyes are dynamic
> in terms of MEASURED refractive STATE.

Why do you say "first step"? It is well established that eyes
change total refractive power moment to moment with accommodation.
Refractive error can also change over time.

Judy