We see very largely with the mind, and only partly with the eyes. The phenomena of vision depend upon the mind’s interpretation of the impression upon the retina. What we see is not that impression, but our own interpretation of it. Our impressions of size, color, form and location can be demonstrated to depend upon the interpretation by the mind of the retinal picture. The moon looks smaller at the zenith than it does at the horizon, though the optical angle is the same and the impression on the retina may be the same, because at the horizon the mind unconsciously compares the picture with the pictures of surrounding objects, while at the zenith there is nothing to compare it with. The figure of a man on a high building, or on the topmast of a vessel, looks small to the landsman; but to the sailor it appears to be of ordinary size, because he is accustomed to seeing the human figure in such positions.
Persons with normal vision use their memory, or imagination, as an aid to sight; and when the sight is imperfect it can be demonstrated, not only that the eye itself is at fault, but that the memory and imagination are impaired, so that the mind adds imperfections to the imperfect retinal image. No two persons with normal sight will get the same visual impressions from the same object; for their interpretations of the retinal picture will differ as much as their individualities differ, and when the sight is imperfect the interpretation is far more variable. It reflects, in fact, the loss of mental control which is responsible for the error of refraction. When the eye is out of focus, in short, the mind is also out of focus.
According to the accepted view most of the abnormalities of vision produced when there is an error of refraction in the eye are sufficiently accounted for by the existence of that error. Some are supposed to be due to diseases of the brain or retina. Multiple images are attributed to astigmatism, though only two can be legitimately accounted for in this way, while some patients state that they see half a dozen or more, and many persons with astigmatism do not see any. It can easily be demonstrated, however, that the inaccuracy of the focus accounts for only a small part of these results; and since they can all be corrected in a few seconds through the correction, by relaxation, of the error of refraction, it is evident that they cannot be due to any organic disease.
If we compare the picture on the glass screen of the camera when the camera is out of focus with the visual impressions of the mind when the eye is out of focus, there will be found to be a great difference between them. When the camera is out of focus it turns black into grey, and blurs the outlines of the picture; but it produces these results uniformly and constantly. On the screen of the camera an imperfect picture of a black letter would be equally imperfect in all parts, and the same adjustment of the focus would always produce the same picture. But when the eye is out of focus the imperfect picture which the patient imagines that he sees is always changing, whether the focus changes or not. There will be more grey on one part than on another, and both the shade and the position of the grey may vary within wide limits in a very short space of time. One part of the letter may appear grey and the rest black. Certain outlines may be seen better than others, the vertical lines, perhaps, appearing black and the diagonal grey, and vice versa. Again, the black may be changed into brown, yellow, green, or even red, transmutations impossible to the camera. Or there may be spots of color, or of black, on the grey, or on the white openings. There may also be spots of white, or of color, on the black.
When the camera is out of focus the picture which it produces of any object is always slightly larger than the image produced when the focus is correct; but when the eye is out of focus the picture which the mind sees may be either larger or smaller than it normally would be. To one patient the big C at ten feet appeared smaller than at either twenty feet or four inches. To some it appears larger than it actually is at twenty feet, and to others it seems smaller.
When the human eye is out of focus the form of the objects regarded by the patient frequently appears to be distorted, while their location may also appear to change. The image may be doubled, tripled, or still further multiplied, and while one object, or part of an object may be multiplied other objects or parts of objects in the field of vision may remain single. The location of these multiple images is sometimes constant and at others subject to continual change. Nothing like this could happen when the camera is out of focus.
If two cameras are out of focus to the same degree, they will take two imperfect pictures exactly alike. If two eyes are out of focus to the same degree, similar impressions will be made upon the retina of each; but the impressions made upon the mind may be totally unlike, whether the eyes belong to the same person or to different persons. If the normal eye looks at an object through glasses that change its refraction, the greyness and blurring produced are uniform and constant; but when the eye has an error of refraction equivalent to that produced by the glasses, these phenomena are nonuniform and variable.
It is fundamental that the patient should understand that these aberrations of vision – which are treated more fully in a later chapter – are illusions, and not due to a fault of the eyes. When he knows that a thing is an illusion he is less likely to see it again. When he becomes convinced that what he sees is imaginary it helps to bring the imagination under control; and since a perfect imagination is impossible without perfect relaxation, a perfect imagination not only corrects the false interpretation of the retinal image, but corrects the error of refraction.
Imagination is closely allied to memory, although distinct from it. Imagination depends upon the memory, because a thing can be imagined only as well as it can be remembered. You cannot imagine a sunset unless you have seen one; and if you attempt to imagine a blue sun, which you have never seen, you will become myopic, as indicated by simultaneous retinoscopy. Neither imagination nor memory can be perfect unless the mind is perfectly relaxed. Therefore when the imagination and memory are perfect, the sight is perfect. Imagination, memory and sight are, in fact, coincident. When one is perfect, all are perfect, and when one is imperfect, all are imperfect. If you imagine a letter perfectly, you will see the letter and other letters in its neighborhood will come out more distinctly, because it is impossible for you to relax and imagine you see a perfect letter and at the same time strain and actually see an imperfect one. If you imagine a perfect period on the bottom of a letter, you will see the letter perfectly, because you cannot take the mental picture of a perfect period and put it on an imperfect letter. It is possible, however, as pointed out in the preceding chapter, for sight to be unconscious. In some cases patients may imagine the period perfectly, as demonstrated by the retinoscope, without being conscious of seeing the letter; and it is often some time before they are able to be conscious of it without losing the period.
When one treats patients who are willing to believe that the letters can be imagined, and who are content to imagine without trying to see, or compare what they see with what they imagine, which always brings back the strain, very remarkable results are sometimes obtained by the aid of the imagination. Some patients at once become able to read all the letters on the bottom line of the test card after they become able to imagine that they see one letter perfectly black and distinct. The majority, however, are so distracted by what they see when their vision has been improved by their imagination that they lose the latter. It is one thing to be able to imagine perfect sight of a letter, and another to be able to see the letter and other letters without losing control of the imagination.
In myopia the following method is often successful:
First look at a letter at the point at which it is seen best. Then close the eyes and remember it. Repeat until the memory is almost as good as the sight at the nearpoint. With the test card at a distance of twenty feet, look at a blank surface a foot or more to one side of it, and again remember the letter. Do the same at six inches and at three inches. At the last point note the appearance of the letters on the card – that is, in the eccentric field. If the memory is still perfect, they will appear to be a dim black, not grey, and those nearest the point of fixation will appear blacker than those more distant. Gradually reduce the distance between the point of fixation and the letter until able to look straight at it and imagine that it is seen as well as it is remembered. Occasionally it is well during the practice to close and cover the eyes and remember the letter, or a period, perfectly black. The rest and mental control gained in this way are a help in gaining control when one looks at the test card.
Patients who succeed with this method are not conscious while imagining a perfect letter, of seeing, at the same time, an imperfect one, and are not distracted when their vision is improved by their imagination. Many patients can remember perfectly with their eyes closed, or when they are looking at a place where they cannot see the letter; but just as soon as they look at it they begin to strain and lose control of their memory. Therefore, as the imagination depends upon the memory, they cannot imagine that they see the letter. In such cases it has been my custom to proceed somewhat in the manner described in the preceding chapter. I begin by saying to the patient:
“Can you imagine a black period on the bottom of this letter, and at the same time, while imagining the period perfectly, are you able to imagine that you see the letter?”
Sometimes they are able to do this, but usually they are not. In that case they are asked to imagine part of the letter, usually the bottom. When they have become able to imagine this part straight, curved, or open, as the case may be, they become able to imagine the sides and top, while still holding the period on the bottom. But even after they have done this, they may still not be able to imagine the whole letter without losing the period. One may have to coax them along by bringing the card up a little closer, then moving it farther away; for when looking at a surface where there is anything to see, the imagination improves in proportion as one approaches the point where the sight is best, because at that point the eyes are most relaxed. When there is nothing particular to see, the distance makes no difference, because no effort is being made to see.
To encourage patients to imagine they see the letter it seems helpful to keep saying to them over and over again:
“Of course you do not see the letter. I am not asking you to see it. I am just asking you to imagine that you see it perfectly black and perfectly distinct.”
When patients become able to see a known letter by the aid of their imagination, they become able to apply the same method to an unknown letter; for just as soon as any part of a letter, such as an area equal to a period, can be imagined to be perfectly black, the whole letter is seen to be black, although the visual perception of this fact may not, at first, last long enough for the patient to become conscious of it.
In trying to distinguish unknown letters, the patient discovers that it is impossible to imagine perfectly unless one imagines the truth; for if a letter, or any part of a letter, is imagined to be other than it is, the mental picture is foggy and inconstant, just like a letter which is seen imperfectly.
The ways in which the imagination can be interfered with are very numerous. There is one way of imagining perfectly and an infinite number of ways of imagining imperfectly. The right way is easy. The mental picture of the thing imagined comes as quick as thought, and can be held more or less continuously. The wrong way is difficult. The picture comes slowly, and is both variable and discontinuous. This can be demonstrated to the patient by asking him first to imagine or remember a black letter as perfectly as possible with the eyes closed, and then to imagine the same letter imperfectly. The first he can usually do easily; but it will be found very difficult to imagine a black letter with clear outlines to be grey, with fuzzy edges and clouded openings, and impossible to form a mental picture of it that will remain constant for an appreciable length of time. The letter will vary in color, shape and location in the visual field, precisely as a letter does when it is seen imperfectly; and just as the strain of imperfect sight produces discomfort and pain, the effort to imagine imperfectly will sometimes produce pain. The more nearly perfect the mental picture of the letter, on the contrary, the more easily and quickly it comes and the more constant it is.
Some very dramatic cures have been effected by means of the-imagination. One patient, a physician, who had worn glasses for forty years and who could not without them see the big C at twenty feet, was cured in fifteen minutes simply by imagining that he saw the letters black. When asked to describe the big C with unaided vision he said it looked grey to him, and that the opening was obscured by a grey cloud to such an extent that he had to guess that it had an opening. He was told that the letter was black, perfectly black, and that the opening was perfectly white, with no grey cloud; and the card was brought close to him so that he could see that this was so. When he again regarded the letter at the distance, he remembered its blackness so vividly that he was able to imagine that he saw it just as black as he had seen it at the near-point, with the opening perfectly white; and therefore he saw the letter on the card perfectly black and distinct. In the same way he became able to read the seventy line; and so he went down the card, until in about five minutes he became able to read at twenty feet the line which the normal eye is supposed to read at ten feet. Next diamond type was given to him to read. The letters appeared grey to him, and he could not read them. His attention was called to the fact that the letters were really black, and immediately he imagined that he saw them black and became able to read them at ten inches.
The explanation of this remarkable occurrence is simply relaxation. All the nerves of the patient’s body were relaxed when he imagined that he saw the letters black, and when he became conscious of seeing the letters on the card, he still retained control of his imagination. Therefore he did not begin to strain again, and actually saw the letters as black as he imagined them.
The patient not only had no relapse, but continued to improve. About a year later I visited him in his office and asked him how he was getting on. He replied that his sight was perfect, both for distance and the near-point. He could see the motor cars on the other side of the Hudson River and the people in them, and he could read the names of boats on the river which other people could make out only with a telescope. At the same time he had no difficulty in reading the newspapers, and to prove the latter part of this statement, he picked up a newspaper and read a few sentences aloud. I was astonished, and asked him how he did it.
“I did what you told me to do,” he said.
“What did I tell you to do?” I asked.
“You told me to read the Snellen test card every day, which I have done, and to read fine print every day in a dim light, which I have also done.”
Another patient, who had a high degree of myopia complicated with atrophy of the optic nerve, and who had been discouraged by many physicians, was benefited so wonderfully and rapidly by the aid of his imagination that one day while in the office he lost control of himself completely, and raising a test card which he held in his hand, he threw it across the room.
“It is too good to be true,” he exclaimed; “I cannot believe it. The possibility of being cured and the fear of disappointment are more than I can stand.”
He was calmed down with some difficulty and encouraged to continue. Later he became able to read the small letters on the test card with normal vision. He was then given fine print to read. When he looked at the diamond type, he at once said that it was impossible for him to read it. However, he was told to follow the same procedure that had benefited his distance sight. That is, he was to imagine a period on one part of the small letters while holding the type at six inches. After testing his memory of the period a number of times, he became able to imagine he saw a period perfectly black on one of the small letters. Then he lost control of his nerves again, and on being asked, “What is the trouble ?” he said:
“I am beginning to read the fine print, and I am so overwhelmed that I lose my self-control.”
In another case, that of a woman with high myopia complicated with incipient cataract, the vision improved in a few days from 3/200 to 20/50. Instead of going gradually down the card, a jump was made from the fifty line to the ten line. The card was brought up close to her, and she was asked to look at the letter O at three inches, the distance at which she saw it best, to imagine that she saw a period on the bottom of it and that the bottom was the blackest part. When she was able to do this at the near-point, the distance was gradually increased until she became able to see the O at three feet. Then I placed the card at ten feet and she exclaimed:
“Oh, doctor, it is impossible! The letter is too small. It is too great a thing for me to do. Let me try a larger letter first.”
Nevertheless she became able in fifteen minutes to read the small O on the ten line at twenty feet.