THE Florentines were doubtless mistaken in supposing that their fellow citizen (see page V) was the inventor of the lenses now so commonly worn to correct errors of refraction. There has been much discussion as to the origin of these devices, but they are generally believed to have been known at a period much earlier than that of Salvino degli Armati.: The Romans at least must have known something of the art of supplementing the powers of the eye, for Pliny tells us that Nero used to watch the games in the Colosseum through a concave gem set in a ring for that purpose. If, however, his contemporaries believed that Salvino of the Armati was the first to produce these aids to vision, they might well pray for the pardon of his sins; for while it is true that eyeglasses have brought to some people improved vision and relief from pain and discomfort, they have been to others simply an added torture, they always do more or less harm, and at their best they never improve the vision to normal.
That glasses cannot improve the sight to normal can be very simply demonstrated by looking at any color through a strong convex or concave glass. It will be noted that the color is always less intense than when seen with the naked eye; and since the perception of form depends upon the perception of color, it follows that both color and form must be less distinctly seen with glasses than without them. Even plane glass lowers the vision both for color and form, as everyone knows who has ever looked out of a window. Women who wear glasses for minor defects of vision often observe that they are made more or less color-blind by them, and in a shop one may note that they remove them when they want to match samples. If the sight is seriously defective, the color may be seen better with glasses than without them.
That glasses must injure the eye is evident from the facts given in the preceding chapter. One cannot see through them unless one produces the degree of refractive error which they are designed to correct. But refractive errors, in the eye which is left to itself, are never constant. If one secures good vision by the aid of concave, or convex, or astigmatic lenses, therefore, it means that one is maintaining constantly a degree of refractive error which otherwise would not be maintained constantly. It is only to be expected that this should make the condition worse, and it is a matter of common experience that it does. After people once begin to wear glasses their strength, in most cases, has to be steadily increased in order to maintain the degree of visual acuity secured by the aid of the first pair. Persons with presbyopia who put on glasses because they cannot read fine print too often find that after they have worn them for a time they cannot, without their aid, read the larger print that was perfectly plain to them before. A person with myopia of 20/70 who puts on glasses giving him a vision of 20/20 may find that in a week’s time his unaided vision has declined to 20/200, and we have the testimony of Dr. Sidler-Huguenin, of Zurich (see note 1), that of the thousands of myopes treated by him the majority grew steadily worse, in spite of all the skill he could apply to the fitting of glasses for them. When people break their glasses and go without them for a week or two, they frequently observe that their sight has improved. As a matter of fact the sight always improves, to a greater or less degree, when glasses are discarded, although the fact may not always be noted.
That the human eye resents glasses is a fact which no one would attempt to deny. Every oculist knows that patients have to “get used” to them, and that sometimes they never succeed in doing so. Patients with high degrees of myopia and hypermetropia have great difficulty in accustoming themselves to the full correction, and often are never able to do so. The strong concave glasses required by myopes of high degree make all objects seem much smaller than they really are, while convex glasses enlarge them. – These are unpleasantnesses that cannot be overcome. Patients with high degrees of astigmatism suffer some very disagreeable sensations when they first put on glasses, for which reason they are warned by one of the “Conservation of Vision” leaflets published by the Council on Health and Public Instruction of the American Medical Association to “get used to them at home before venturing where a misstep might cause a serious accident (see note 2)”. Usually these difficulties are overcome, but often hey are not, and it sometimes happens that those who get on fairly well with their glasses in the daytime never succeeded in getting used to them at night.
All glasses contract the field of vision to a greater or less degree. Even with very weak glasses patients are unable to see distinctly unless they look through the center of the lenses, with the frames at right angles to the line of vision; and not only is their vision lowered if they fail to do this, but annoying nervous symptoms, such as dizziness and headache, are sometimes produced. Therefore they are unable to turn their eyes freely in different directions. It is true that glasses are now ground in such a way that it is theoretically possible to look through them at any angle, but practically they seldom accomplish the desired result.
The difficulty of keeping the glass clear is one of the minor discomforts of glasses, but nevertheless a most annoying one. On damp and rainy days the atmosphere clouds them. On hot days the perspiration from the body may have a similar effect. On cold days they are often clouded by the moisture of the breath. Every day they are so subject to contamination by dust and moisture and the touch of the fingers incident to unavoidable handling that it is seldom they afford an absolutely unobstructed view of the objects regarded.
Reflections of-strong light from eyeglasses are often very annoying, and in the street may be very dangerous.
Soldiers, sailors, athletes, workmen and children have great difficulty with glasses because of the activity of their lives, which not only leads to the breaking of the lenses, but often throws them out of focus, particularly in the case of eyeglasses worn for astigmatism.
The fact that glasses are very disfiguring may seem a matter unworthy of consideration in a medical publication; but mental discomfort does not improve either the general health or the vision, and while we have gone so far toward making a virtue of what we conceive to be necessity that some of us have actually come to consider glasses becoming, huge round lenses in ugly tortoiseshell frames being positively fashionable at the present time, there are still some unperverted minds to which the wearing of glasses is mental torture and the sight of them upon others far from agreeable. Most human beings are, unfortunately, ugly enough without- putting glasses upon them, and to disfigure any of the really beautiful faces that we have with such contrivances is surely as bad as putting an import tax upon art. As for putting glasses upon a child it is enough to make the angels weep.
Up to a generation ago glasses were used only as an aid to defective sight, but they are now prescribed for large numbers of persons who can see as well or better without them. As explained in Chapter I, the hypermetropic eye is believed to be capable of correcting its own difficulties to some extent by altering the curvature of the lens, through the activity of the ciliary muscle. The eye with simple myopia is not credited with this capacity, because an increase in the convexity of the lens, which is supposed to be all that is accomplished by accommodative effort, would only increase the difficulty; but myopia is usually accompanied by astigmatism, and this, it is believed, can be overcome, in part, by alterations in the curvature of the lens. Thus we are led by the theory to the conclusion that an eye in which any error of refraction exists is practically never free, while open, from abnormal accommodative efforts. In other words, it is assumed that the supposed muscle of accommodation has to bear, not only the normal burden of changing the focus of the eye for vision at different distances, but the additional burden of compensating for refractive errors. Such adjustments, if they actually took place, would naturally impose a severe strain upon the nervous system, and it is to relieve this strain – which is believed to be the cause of a host of functional nervous troubles – quite as much as to improve the sight, that glasses are prescribed.
It has been demonstrated, however, that the lens is not a factor, either in the production of accommodation, or in the correction of errors of refraction. Therefore under no circumstances can there be a strain of the ciliary muscle to be relieved. It has also been demonstrated that when the vision is normal no error of refraction is present, and the extrinsic muscles of the eyeball are at rest. Therefore there can be no strain of the extrinsic muscles to be relieved in these cases. When a strain of these muscles does exist, glasses may correct its effects upon the refraction, but the strain itself they cannot relieve. On the contrary, as has been shown, they must make it worse. Nevertheless persons with normal vision who wear glasses for the relief of a supposed muscular strain are often benefited by them. This is a striking illustration of the effect of mental suggestion, and plane glass, if it could inspire the same faith, would produce the same result. In fact, many patients have told me that they had been relieved of various discomforts by glasses which I found to be simply plane glass. One of these patients was an optician who had fitted the glasses himself and was under no illusions whatever about them; yet he assured me that when he didn’t wear them he got headaches.
Some patients are so responsive to mental suggestion that you can relieve their discomfort, or improve their sight, with almost any glasses you like to put on them. I have seen people with hypermetropia wearing myopic glasses with a great deal of comfort, and people with no astigmatism getting much satisfaction from glasses designed for the correction of this defect.
Landolt mentions the case of a patient who had for years worn prisms for insufficiency of the internal recti, and who found them absolutely indispensable for work, although the apices were toward the nose. The prescription, which the patient was able to produce, called for prisms adjusted in the usual manner, with the apices toward the temples; but the optician had made a mistake which, owing to the patient’s satisfaction with the result, had never been discovered. Landolt explained the case by “the slight effect of weak prisms and the great power of imagination (see note 3)”; and doubtless the benefit derived from the glasses was real, resulting from the patient’s great faith in the specialist – described as “one of the most competent of ophthalmologists” – who prescribed them.
Some patients will even imagine that they see better with glasses that markedly lower the vision. A number of years ago a patient for whom I had prescribed glasses consulted an ophthalmologist whose reputation was much greater than my own, and who gave him another pair of glasses and spoke slightingly of the ones that I had prescribed. The patient returned to me and told me how much better he could see with the second pair of glasses than he did with the first. I tested his vision with the new glasses, and found that while mine had given him a vision of 20/20 those of my colleague enabled him to see only 20/40. The simple fact was that he had been hypnotized by a great reputation into thinking he could see better when he actually saw worse; and it was hard to convince him that he was wrong, although he had to admit that when he looked at the test card he could see only half as much with the new glasses as with the old ones.
When glasses do not relieve headaches and other nervous symptoms it is assumed to be because they were not properly fitted, and some practitioners and their patients exhibit an astounding degree of patience and perseverance in their joint attempts to arrive at the proper prescription. A patient who suffered from severe pains at the base of his brain was fitted sixty times by one specialist alone, and had besides visited many other eye and nerve specialists in this country and in Europe. He was relieved of the pain in five minutes by the methods presented in this book, while his vision, at the same time, became temporarily normal.
It is fortunate that many people for whom glasses have been prescribed refuse to wear them, thus escaping not only much discomfort but much injury to their eyes. Others, having less independence of mind, or a larger share of the martyr’s spirit, or having been more badly frightened by the oculists, submit to an amount of unnecessary torture which is scarcely conceivable. One such patient wore glasses for twenty-five years, although they did not prevent her from suffering continual misery and lowered her vision to such an extent that she had to look over the tops when she wanted to see anything at a distance. Her oculist assured her that she might expect the most serious consequences if she did not wear the glasses, and was very severe about her practice of looking over instead of through them.
As refractive abnormalities are continually changing, not only from day to day and from hour to hour, but from minute to minute, even under the influence of atropine, the accurate fitting of glasses is, of course; impossible. In some cases these fluctuations are so extreme, or the patient so unresponsive to mental suggestion, that no relief whatever is obtained from correcting lenses, which necessarily become under such circumstances an added discomfort. At their best it cannot be maintained that glasses are anything more than a very unsatisfactory substitute for normal vision.