Visual fixation

“ Accurate reports are usually obtained more quickly by means of convex glasses or eserine. In any case insufficient accommodation is, according to this, one of the difficulties, but not the only one, which has to be overcome before the squinting eye can be put into fixation. We can understand that the innervation necessary for distinct vision can be set aside even without loss of visual acuteness, just as we see the movement of convergence disappear without the interni losing their capacity for contraction. ”

“ She soon became able to look at one part of the smallest letters on the card and see the rest worse, and then she became able to read the letters at twenty feet.
On the principle that a burnt child dreads the fire, some patients are benefited by consciously making their sight worse. When they learn, by actual demonstration of the facts, just how their visual defects are produced, they unconsciously avoid the unconscious strain which causes them. When the degree of eccentric fixation is not too extreme to be increased, therefore, it is a benefit to patients to teach them how to increase it. ”

“ Why should a man strain his accommodation when no advantage is thereby gained?
In most cases the squinting eye has also an available power of vision and is on that account used for fixing objects which lie in the direction of its visual axis; it can also be made to fix objects in front, this occurs as soon as the other eye is covered; it remains as the fixing eye till the next blinking of the lids, or movement to another object for fixation, or till both eyes are closed for a short time, when it returns to its former deviation. ”

“ It is still more frequently the case that visual acuteness is stated to be less than it is in reality. The result of always using the better eye for fixation is, that fixation is not learnt with the weaker one. Even where there is no squint we see very frequently that in one-sided hypermetropia the accommodation is only used in that proportion which has become habitual to the emmetropic eye and does not therefore suffice to produce clear retinal images, while good visual acuteness is obtained by means of the correcting convex glasses. ”

“ In a condition of rest the axes of vision of the eyes tend to become parallel; and from this point onward the intensity of the effort accompanying the process of fixation increases until, when the object has passed the near-point of vision, binocular adjustment is no longer possible. In the general distribution of objects in the visual field the nearer, for the human being, is characteristically the lower, the more distant the higher, as one looks in succession from the things at his feet to the horizon and vice versa. ”

“ Slight vertical differences in fixation would cause the central part of the path taken by the moving light to become more fatigued than the edges and so to respond more slowly to the stimulation and reverse the curvature. It may be that some brain process which has to do with the apperception of the form and movement of visual objects becomes fatigued or does not always function properly, and so the curvature of the image may sometimes appear reversed. ”

“ The eye with normal vision, therefore, sees one part of everything it looks at best, and everything else worse, in proportion as it is removed from the point of maximum vision; and it is an invariable symptom of all abnormal conditions of the eyes, both functional and organic, that this central fixation is lost. ”

“ After he has demonstrated these facts he is told that persons with imperfect sight always attempt to hold their points of fixation too long, even when the lowering of vision is caused by an injury, or by a foreign body in the eye. ”

“ With others, all efforts are in vain, it is impossible to render them conscious of the double images, notwithstanding that the presence of the binocular disturbance of vision proves that the habit of binocular fixation exists. ”

“ He explains this by the supposition that the retinal impression is strengthened by the same retinal areas being rapidly and repeatedly subjected to the action of the rays of light from the same object, while a longer period of fixation would cause retinal fatigue and blur; showing the same principle by reminding us that our perceptive powers for a test object, upon first being brought into view at the periphery of the field of vision, are much stronger when the object is shaken than when it is brought quietly toward the fixation-point. ”

“ Shifting and Swinging.—The eye with normal vision never regards a point for more than a fraction of a second, but shifts rapidly from one part of its field to another, thus producing a slight apparent movement, or swing, of all objects regarded. The eye with imperfect sight always tries to hold its points of fixation, just as it tries to see with maximum vision a larger area at once than nature intended it to see. ”

“ Such practices as reading alternately in a bright and a dim light, or going from a dark room to a well-lighted one, and vice versa, are to be recommended. Even such rapid and violent fluctuations of light as those involved in the production of the moving picture are, in the long run, beneficial to all eyes. I always advise patients under treatment for the cure of defective vision to go to the movies frequently and practice central fixation. ”

“ A traumatic cataract is one which follows an injury (trauma) to the lens, the opacity being due largely to the formation of connective tissue in the pupil, and, in advance of the event, I should have pronounced the cure of such a condition impossible, although I had previously demonstrated that when patients practice central fixation connective tissue is absorbed in the optic nerve, retina and cornea. In the retina and optic nerve the circulation can be seen to improve as the connective tissue disappears, and I can only assume that this is the cause of its disappearance. ”

“ In the absence of any nerve lesions, central or other, interfering with their associated movements, the eyes continue throughout life to respond equally to the stimuli which cause these movements, even when, owing to a visual defect of the one eye, binocular vision has become impossible. ”

“ You ask how men have arrived at the knowledge of these things, seeing the mechanism in question is almost entirely removed from any direct investigation. First, then, the umbellar expansion of the optic nerve, the retina, enables us to make experiments; this retina being in such close contact with the eye, the optical part of the visual organ, that it is accessible to every sort of mechanical irritation. ”

“ Since central fixation is impossible without mental control, central fixation of the eye means central fixation of the mind. It means, therefore, health in all parts of the body, for all the operations of the physical mechanism depend upon the mind. Not only the sight, but all the other senses--touch, taste, hearing and smell--are benefited by central fixation. All the vital processes--digestion, assimilation, elimination, etc.--are improved by it. The symptoms of functional and organic diseases are relieved. The efficiency of the mind is enormously increased. ”

“ The highest degrees of eccentric fixation occur in the high degrees of myopia, and in these cases, since the sight is best at the near-point, the patient is benefited by practicing seeing worse at this point. ”

“ It reaches its maximum of effect immediately after the introduction of the contrasting field, and then, if the fixation is continued, it begins to weaken rapidly and soon disappears; thus undergoing changes similar to those observed when any field whatever is fixated steadily and the retina becomes fatigued by unchanging stimuli. If one continues still further to fixate the same point, the color and brightness of one field tend to spread themselves over and mingle with the color and brightness of the neighboring fields, thus substituting 'simultaneous induction' for simultaneous contrast. ”

“ In no case have I been able to bring about retraction of the eye-stalk by visual stimulation, but a very light touch-stimulus on the eye itself or on the eye-stalk or a stronger stimulus on some portion of the head will cause the eye to be drawn in. It is true that after repeated stimulation the eye is retracted no longer, and with a heavy bristle one can make a perceptible indentation in the corneal surface without the eye being withdrawn. ”

“ In most cases of eccentric fixation, on the contrary, the eye quickly tires, and its appearance, with that of the face, is expressive of effort or strain. The ophthalmoscope1 reveals that the eyeball moves at irregular intervals, from side to side, vertically or in other directions. ”

“ AS noted in the chapter on What Glasses Do to Us, the sight always improves when glasses are discarded, though this improvement may be so slight as not to be noticed. In a few unusual cases the patients, when freed from the handicap of a condition which compels them to keep their eyes continually under a strain, find out, in some way, how to avoid strain, and thus regain a greater or less degree of their normal visual power. ”

“ As the disc revolves, each hole in turn crosses the line EL. Thus the luminous hole H is successively covered and uncovered to the eye E; and if the eye moves, a succession of points on the retina is stimulated by the successive uncovering of the luminous spot. No fixation-points are provided for the eye, since such points, if bright enough to be of use in the otherwise dark room, might themselves produce confusing streaks, and also since an exact determination of the arc of eye-movement would be superfluous. ”

“ The editor is practically alone in advocating central fixation. A small number of physicians, including a few eye specialists, who have been cured or seen members of their families cured of eye troubles, without glasses, operations, or medication, have been convinced that the old theories about the eye and the treatment of defects of vision are wrong ”

“ If we were to divide the optic nerve where it passes into the foramen, taking care to leave the apparatus of the eye uninjured, the visual organ would be deprived of its function, and the person or animal would be completely blind of that eye; so that a communication with the brain is necessary for the purpose or act of perception. ”

“ The commonest visual defects are, first, inflammation of the cornea, or imperfections of the lens—the cornea is often so scarred as to make vision imperfect; second, myopia, or progressive shortsightedness, a condition in which the axis of the eye gradually grows longer. This lengthening is accompanied by stretching of the eyeball, and such children always run the risk of the inner and most important part of the wall of the eye, the retina or nerve layer, being torn away, and blindness resulting. ”

“ It can be taken as a fact, which the theory of the action of the eye implies, that for each external impression, that is, for each image produced upon the retina, the ends of the visual nerves, concerned in the conveyance of the impression to the mind, must be under a peculiar stress or in a vibratory state. ”

“ The blind spot does not indicate diseased eyes, but it simply marks the point where the optic nerve enters the eyeball, which point is not provided with the necessary visual end organs of the sight, known as rods and cones. ”

“ Although the blurred and indefinite retinal picture may be compensated, and perhaps more than compensated, by the readiness with which the eyes move, it is, of course, possible that greater precision and delicacy of visual impression over the whole surface of the retina might be consistent with a still greater increase of our powers of perception. There are instances in which the absence of finish, as it may be termed, in all but one little spot in the picture, proves a real inconvenience and a sensible deprivation. ”

“ Careful observation of clinical cases has, for example, shown that a lesion in the visual center of the brain, that is, the part of the brain to which the fibers of the optic nerve run, induces the disappearance of both sight and visual imagery. ”

“ Eccentric fixation, even in its lesser degrees, is so unnatural that great discomfort, or even pain, can be produced in a few seconds by trying to see every part of an area three or four inches in extent at twenty feet, or even less, or an area of an inch or less at the near-point, equally well at one time, while at the same time the retinoscope will demonstrate that an error of refraction has been produced. ”

“ The explanation presupposes that sensations of eye-movements have nothing to do with the projection of retinal impressions into the visual field, that is, with the perception of the mutual relations as to direction and distance, of objects which are viewed simultaneously.... Undoubtedly, however, sensations of eye-movements, and of head-and body-movements as well, afford us a scale for measuring the displacements which our entire visual field and every point in it undergo within the surrounding totality of space, which we conceive of as fixed. ”

“ If, on the other hand, the eyes are turned to the side, that is, if the ideal fixation-line forms an acute angle with the line connecting the eyeballs, the two fixated light-points, which lie in a plane perpendicular to the fixation-line, cannot be seen by the two eyes under the same angle. Any object on my right side is somewhat nearer to my right eye than to my left, and therefore must throw a larger image on my right retina. The two light-points of a plane vertical to the fixation-line give thus with the eyes turned to the right two unequal pairs of retinal stimuli ”