Looking through this Ophthalmology Secrets in Color e-book I found is highly informative.  Secret number 5 states that "The goal of refractive correction is to place the circle of least confusion into the retina."  I ask myself what the circle of least confusion is.  After reading the technical explanation, which is: "The circle of least confusion is the circular cross-section of Sturm’s conoid, dioptrically midway between the two focal lines."  Okay, so what's Sturm's conoid? Come to find out that it is simply a name for the midpoint of the vertical and horizontal focal planes in an astigmatic system.  So when light passes through an astigmatic lens, which is essentially distorted in shape so that the vertical and horizontal focal distances are different, it theoretically behaves similar to the way described by Sturm's conoid.  Instead of a clear image being produced, the source of light  is perceived through many distorted images where one is closer to clarity than the others.  The source closest to clarity is where the circle of least confusion resides.  The diagram according to Avery Deh Prangen, M.D. is not the best visual for understanding the various problems that arise from astigmatism.

Since my prescription was for astigmatism, I found it useful to know what it really is.  Simply put, it is a kind of wrinkle in the lens of the eyeball according to Greg Marsh, a natural vision coach and chemical engineer college graduate.  The extraocular muscles of the eyeballs become so asymmetrically constricted that the cornea distorts as well producing astigmatism.  Dr. Bates was very curious about voluntary errors of refraction and was able to turn hyperopes into myopes.  In other words, people who were farsighted could voluntarily become nearsighted through the instruction of Dr. Bates.  He found that many of his patient's errors of refraction would change throughout the day - sometimes their vision was good or decent and sometimes poor or practically dysfunctional.  He spent much of his time during his practice studying the effect that the mind has on the eye.

While understanding the mechanics of astigmatism can be interesting and helpful, much of the information is superfluous when it comes to the Bates Method.  It's almost like trying to make music from a purely theoretical standpoint.  It may sound organized and well-thought out but the emotional effect it has on people is likely to be weak.  The Bates Method must be experienced and practiced. No amount of complex thought is going to give you any more power over your eyesight.  If anything, complex thoughts are likely to produce strain, which tends to cause errors of refraction.  Another reason why I feel as if testimonial research is more practical for this particular project.  I cannot become an ophthalmology expert on such short notice.  Testimonial research will present a more human approach to improving eyesight.  It will consist of people's explanations of how they thought about the Bates Method and what emotions, which is important, they experienced as well.  Try to convince me that you're emotionally content when you cannot see well... I doubt you will.  Emotions as we all know can and often very easily cause strain.  The good news is that they can undo it as well.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1315872/?page=1