these two are idiots. just let them continue this laughable dialogue
and see how far it goes. this is about as good as Otis and his myopia
expert buddy discussing the strengths and weaknesses of the Shotwell
study. "-96 diopter myopia". "tissues torn apart". "pruspose". give
me a break.

Thats true some people become blind from retina detachments before they
reach insane levels of myopia but supposedly this guy reached -104
diopters and while legally and nearly blind, he could still "see" a
little with two pairs of lenses cemented to each other! As long as the
patient has some vision left, myopia is measured and glasses fitted.

Myopia in the -20 to -30 range sometimes leaves the retina intact
enough to provide the patient with acceptable vision with myodisc
glasses, usually better than 20/200 corrected.

"otisbrown[at]pa.net" <otisbrown[at]pa.net> wrote:

- quote -

Prus-pose. Noun. An explanation for early-onset alzheimers
characterised by delusions of grandeur, antisocial behaviors, and
narcissistic personality disorder.
--
Live simply so that others may simply live

Dear Ace,

Very difficult to say. In my opinion, the tissues would
be torn apart by they time you got this much change.

My "pruspose" is to prevent -- before this process
even starts.

But then I am "out numbered" on that point.

Best,

Otis

understood but does this make it possible to have myopia in the triple
digits? How far can myopia progress? -120? -150? -200? -1000?

Dear Ace,

Here are the basic equations of physiological
optics. If you assume that the eye
is a "box camera" (Gullistrand model)
the calculations are quite simple.

(From Chapter 3 my book)

+++++++++++++

BASIC OPTICAL PHYSICS

In order to understand the design and behavior of the normal eye it is
necessary to understand its basic optical properties.

When a light ray enters water it is refracted (bent). The equation that
describes this bending is shown below. Water has an Index-of-Refraction
of 1.33. The normal eye has 1.38 as an over-all Index-of-Refraction.
(Figure 1)

SNELL'S LAW OF REFRACTION

Figure 1.

When light travels through a curved surface, the light rays converge on
a single point. Since an image is made up of a large number of points
of light, an image will form where the light rays converge. (Figure 2)

THE APPROXIMATE REFRACTIVE CHARACTERISTIC OF THE EYE

Figure 2 (from Gullstrand's schematic eye, Reference 1).

The distance between the surface of the lens and the point of image
formation is called the focal length.

Focal Power = (Refractive Index) / (Focal Length)

By using this equation it is possible to analyze the basic optical
properties of the eye. The approximate dimensions of the eye have been
established. The radius of the cornea is 0.66 centimeters, the index of
refraction is 1.38, and the length of the eye is 2.4 centimeters. By
using these numbers we can calculate the focal power of the normal eye.
(For reasons of clarity, I have not included the effect of the internal
lens. A more detailed analysis can be found in Reference 1.)

Focal Power = 1.38 / .024 Meters

Focal Power = 57 Diopters

+++++++++++

You can continue with these
calculations. DrG and the
other ODs can confirm you
the formula and your math for you.

Best,

Otis

Originally Posted by Lewy
I remember attending a seminar by Norvilles several years ago. One of
the questions asked at the time was "What is the highest minus lens you
have dispensed". Personally I have dispensed a -33.00 as a bonded
lenticular. In the audience the highest quoted was -42.00.............
Norvilles topped it by a large margin, they had had an order for
-96.00, YES you read it correctly, -96.00. To make the lenses thay had
to cement 2 lenses back to back and each had an aperture of approx
12mm. A year later they had another order for the same client for
-104.00, they physically couldn't make it.

Consensus of opinion was a guide dog or white stick would have been a
better bet.

Lewy



minus 96 diopters? holy is this even possible? I saw one website that
says they once made a -70 glasses and they said it was a world record
too! His eyes got worse by -8 in one year? Wow whats his corrected
vision? something like 20/2000? His uncorrected vision would be
LP(light perception)
How much myopia is physically possible? Wouldnt your eyeballs be more
than twice as long as normal, your corneas extremely steep, your lenses
like three times thicker?