Dear Scientific Friends,

Subject:  EXACT definitions of words IS ESSENTIAL FOR SCIENCE.

Calling the refractive STATES of the fundamental eye "organic errors",
or "errors" at all, truly is a mistake.

But the language of science is the language of mathematics.

It is therefore necessary to convert "English terms", into words with
PRECISE MATHEMATICAL MEANINGS.

That is the reson for preparing this Glossary -- so we can communicate
effectively about the proven dynamic behavior of the fundamental eye
-- as measured in terms of refractive STATES.

Academic freedom and freedom of ENTERING into a negative refractive
STATE.

Enjoy,

==============

Book Glossary
GLOSSARY FOR THE BOOK:

HOW TO AVOID NEARSIGHTEDNESS
Accommodation

   A blur controlled system that continuously monitors and
   changes the internal lens of the eye — too provide the
   sharpest focus possible.  The retina controls this
   lens-system.

Accommodation, Average Value

   The value of accommodation that is averaged over a 16 hour
   day.

Analog Computer

   Generally, a simulation of a physical or physiological system,
   by using electronic operational amplifiers.  The computer is
   an analogy of the physical system being tested.  This type of
   computer is used when direct mathematical analysis is too
   cumbersome or complicated to use.

Astigmatism

   There is a “normal range” for astigmatism.  It is between zero and
   two diopters.  The FAA requires that you have 20/20 and less than
   two diopters of astigmatism.  If you have 20/20
   there is no point to wearing glasses for astigmatism.

Black Box Testing

   A type of testing where it is necessary to establish a
   fundamental parameter of a previously untested system.  In
   general, you control one parameter, while monitoring the
   effect on the second parameter.

Scientific Confirmation

   Scientific testing in several different locations by different
   scientists where the same result is always obtained.  When the
   results are consistent (as are tests conducted to determine
   the fundamental behavior characteristic of the normal eye) the
   result is considered to be an established fact.

Control System

   A system, generally using power amplification, designed to
   keep one parameter (i.e.  the eye’s desired focal state)
   within tight limits with respect to another parameter (i.e.
   average value of accommodation).

Corrective Lens

   A term growing out of the Helmholtz-passive concept of the
   eye.  It means that if a normal eye has a focal state of + 1.0
   diopter then the “corrective” lens for the normal eye should
   be + 1.0 diopters. In a similar vein, if a normal eye has a
   focal state of -1.0 diopters, the “corrective” lens should be
   -1.0 diopters.

Cybernetics

   The study of control systems in electronic and physiological
   systems.  The analysis and comparison of feedback systems in
   man and machine.

Diopter

   A unit of optical power.  A focal length of one meter
   (approximately on yard, or 39.4 inches).  The reciprocal of
   distance.  A focal length of 1/2 meter represents a focal
   power of 2 diopters.

Emmetropia

   A focal state of exactly zero for the eye. (Under the
   Helmholtz-passive concept, the only “normal” focal state of
   the eye.)

Experiment

   The explicit steps you must take to determine a fact.  (In the
   case of the eye, the explicit steps you must take to determine
   the fundamental behavior characteristic of all normal eyes.)

Eye Acuity Testing

   The type of testing whereby you are required to read the
   standard Snellen eye chart at 20 feet.  (The letters are 3/8
   inch tall, and your successful reading of the chart indicates
   20/20 vision.)

Eye

   A dynamic system (similar to a camera) that controls light
   rays so that they will form an image on the retina.

Facts

   Explicit measurement results that can be repeated as many
   times as desired.  The entity to be tested, must be explicitly
   identified (i.e.  the normal eye) to get consistent results.
   (You cannot run a test on the defective eye and reach a
   conclusion about the normal eye’s behavior.)

Farsightedness (Hyperopia)

   A positive focal state of the natural eye.

Feedback Control

   A method of linking (desired) output to (controlling) input.

First Class Medical

   A Federal Aeronautics Administration (FAA) examination
   required of you to be fully qualified as a professional pilot.
   The chief visual requirement is the ability to read the 20/20
   line on the eye chart.  This represents a focal state of from
   0 to +1.5 diopters.  There is a visually less stringent
   (20/50) 3rd class medical certificate issued by the FAA.

Focal Length

   The point at which an image will form after light rays pass
   through a lens, provided the object is located at a
   considerable distance from the lens.

Focal Measurement

   The process of determining the focal length of a lens, or the
   focal status of the eye.

Focal Power

   The ability of a lens to focus light rays. The shorter the
   focal length, the greater the focal power.

Heuristic

   Serving to discover or to stimulate investigation. Assisting
   in the development of methods of demonstration which tend to
   lead a person to investigate further by himself.

Hyperopia

   A positive focal state of the normal eye.  (Sometimes called
   “Farsightedness”.  This is not a defect of the eye.”

Infinity

   For optical eye-testing purposes, a distance greater than 20
   feet.  Rays of light are considered to be parallel when the
   object is located at infinity.

Magnifying Glass

   A positive lens

Mathematical Model

   A conceptual scheme developed to represent physical reality.
   Mathematical models are essential to science, and are valued
   for their practical technical accuracy and the elegance and
   simplicity of their premise.

Model

   A mechanical or electronic analogy of physical reality or a
   physical system.

Myopia

   See nearsightedness

Nearsightedness

   A negative focal state of the normal eye.  (As defined and
   established in this book.)

Negative Lens

   A lens that optically moves all objects closer to the eye.
   Also called a diverging lens.  A lens with a negative (or
   virtual) focal length.

Noise

   Unwanted or undesired perturbations in a system.  Usually
   defined as having a broad bandwidth.

Operational Amplifier

   An amplifier specifically designed to perform some
   mathematical operation:  (e.g., integration, differentiation,
   multiplication, division, addition, and subtraction.)

Ophthalmologist

   A medical doctor specializing in diseases of the eye.  He is
   required to have four years of college, four years of medical
   school, two years as an intern, and board certification as an
   ophthalmologist.

Optometrist

   A professional who has completed five years of specialized
   college and is licensed to prescribe lenses for refractive
   errors of the eye.

Paradigm

   A conceptual scheme that has received broad acceptance by
   scientists.

Perturbation

   An unexpected and abrupt change to a system in a random
   direction with random magnitude.

Physiological Optics

   The application of optical analysis, using Snell’s law.  The
   analysis of image formation in the eye and the representation
   of the normal eye as a purely optical device.

Positioning Control System

   A system, usually employing power amplification, designed for
   the sole purpose of maintaining very accurate relative
   position.

Positive Lens

   A lens that optically moves all objects away from the eye. A
   magnifying lens.  A converging lens.

Presbyopia

   A situation resulting from the stiffness of the internal lens
   of the eye associated with old age.  Sometimes (inaccurately)
   called farsightedness.

Reading Glass

   A magnifying glass, or positive lens.

Retina

   The light sensitive surface on the back of the eye.

Science

   The systematic assessment of facts.  The theoretical and
   experimental effort required to determine factual truth.

Servo System

   A system, either mechanical or physiological, that “slaves”
   the output to the input.  (The normal eye continually adjusts
   both its corneal power and relative length to maintain
   accurate focus.  The focal state of the normal eye is “slaved”
   to its average visual environment.)

Statistical Testing

   A mathematical method of organizing experimental data to
   rapidly come to a reasonable conclusion about experimental
   (factual) reality.

Testing

   A systematic approach to confirming a physical fact concerning
   some defined entity.  (The normal eye is a defined entity.)

Theory

   A concept developed over the years for explaining an
   underlying physical reality.

Thought Experiment

   A type of experiment that is designed to expose an old theory
   to existing knowledge in a way that isolates the root of the
   problem with a clarity that is unattainable in the laboratory.

Tonic Accommodation

   A normal (and usually negative) neurological focal state for
   the eye.  It occurs any time the retina is unable to perceive
   blur (which the accommodation system needs to focus properly)
   in its field of vision.  This is also referred to as
   blank-field, or dark-focus accommodation.

Transfer Function

   A mathematical function that relates the transformation of the
   output response to the input signal.  In the case of the
   eye, “input” is the accommodation signal, and the “output”
   is the measured focal status of the eye.

Verification Process

   A method of repeated testing to determine factual
   (experimental) truth.

Visual Acuity

   In the normal human eye, visual acuity is given as 1 minute of
   angle, or the ability to read 3/8 inch letters clearly at 20
   feet.  Also referred to as 20/20 vision.  At night, the
   resolving power (i.e.  separation of stars) is about 3 to 5
   minutes of arc.  Some system refer 6 meters as the measurement
   distance.  Thus 20/20 is 6/6.  A newer system uses this
   fraction as the standard, thus 6/6 is 1.0, and 6/12 (20/40) is
   0.5.

   The U. S. Army discovered (ca. 1914) that the 1 minute of
   angle was an excessive requirement.  A great many soldiers could
   pass the 20/40 line — but not the 20/20 line.

   The Army did not wish to have a great mass of soldiers wearing
glasses so they
   set the standard at 20/40 — and would not prescribe minus lenses
   if the soldier could read better-than that line.  This level
   of vision has become standard throughout the world as the
   DMV-Snellen standard.  You must always pass this line if you
   wish to avold wearing minus-lens glasses.