THE MYOPTER: RATIONALE
While searching for additional information about myopia that might help prevent my own slight myopia problem from getting worse, I learned, shortly after graduation from college, that some optometrists were prescribing plus lenses for myopes because they felt that myopia was caused by constant focusing up close.
Since I was about 1 D myopic, I obtained a pair of +2 D lenses. This was equivalent to a +3 D add and enabled me to read without having to accommodate. Every time I wanted to read something, I would put on these reading glasses and hold the book far enough away that it was blurred. At about the same time that I started on this reading glass program, I moved to Arizona for six months. I was living an outdoor life in the sunshine with no office work. I did some reading, but it was always done with the reading glasses. After six months of this kind of life, I found to my pleasure that there had actually been a real improvement in my vision. For example, I could read lighted road signs at night that had previously been blurred. I had hardly any trouble reading anything in the distance. I even had to change to +3 D reading glasses so I wouldn't have to hold the book so far away to get the blurred effect. Needless to say, this experience confirmed for me that the hereditary theory was wrong. What I did not realize at the time was that I only had part of the answer, as shown by a subsequent experience.
I then moved North and began the usual eight-to-five type of office job involving a lot of reading, design work, etc. I soon noticed that the earlier improvement in my vision was beginning to disappear. In fact, after a couple of years of this kind of work, my vision had become worse than ever, in spite of my consistent use of the reading glasses for all close work (I was now back to using the +2 D glasses). It seemed as if the method worked fine if I only did a small amount of reading, but did not work very well if I did a lot of reading. This did not make sense, and it was obvious that there was still a piece missing in the puzzle of myopia control. I got a clue to the puzzle when I learned about someone else who was also using the reading glass technique but was forced to stop.
In this person's case, using the reading glasses set up some kind of stress in the external muscles of the eyes that caused double vision or lack of fusion. After doing a little research on the subject, I learned the reason for this. Reading without accommodation, but with normal convergence, upsets the normal accommodation/convergence relationship so much that some people's eyes give up the attempt at fusion, causing the double vision. In other words, their eyes cannot "accept" this much add. This is especially evident in people whose eyes have a latent tendency to diverge -- a condition called exophoria. They may not be aware of this convergence insufficiency. However, when accommodation is no longer available to stimulate the convergence, double vision can occur. This condition would be present if strong reading glasses are used or if the person has developed several diopters of myopia and is not using a minus correction. (Those whose eyes have a latent tendency to converge have the opposite condition -- esophoria).
Could it be that something similar was happening to my own eyes? Could it be that the stress set up in my eyes, while not enough to cause loss of fusion, was enough to prevent complete relaxation of the eyes? I decided that to get this complete relaxation it would be necessary to put an optical system in front of the eyes that would fully simulate distance vision so that the eyes could read under natural conditions of full relaxation.
In order to eliminate all of these problems and create a completely natural and relaxed distance environment when reading, the instrument had to be designed to eliminate three things which are associated with near vision. These are 1) accommodation, 2) convergence, and 3) stereopsis.
Accommodation and convergence have already been explained in previous chapters. Stereopsis is something new and requires some explanation. Stereopsis is more commonly known as stereoscopic effect or three-dimensional effect. It can be illustrated by holding an object such as a pencil a short distance from your nose. By closing first one eye and then the other, you will notice that the right eye can see further around the right side of the object and the left eye can see further around the left side of the object. In other words, each eye sees a different view of the object. The image seen by one eye differs in both appearance and position from the image seen by the other eye. The brain blends these two different images into one image which appears to have a three-dimensional form. Distant objects, on the other hand, do not appear in three dimensions because they are far enough away that each eye sees the same image.
When we look at a distant object, the three factors of accommodation, convergence, and stereopsis are normally zero or minimal. As the viewed object approaches the eyes, these three factors increase more or less in proportion to each other.
These three factors cannot be eliminated with any form of eyeglasses. Eyeglasses can simulate distance vision only partially because they fail to eliminate all of the close work stress and, in addition, they inevitably create new stresses of their own. The greater the add that is prescribed for the reading glasses or bifocal (to eliminate as much accommodation as possible), the more stress is set up in the visual system.