Eye strain

“ Other eyes which do not focus clearly on objects near at hand are said to be farsighted. Still another eye defect is astigmatism, which causes images of lines in a certain direction to be indistinct, while images of lines transverse to the former are distinct. Many nervous troubles, especially headaches, may be due to eye strain. We should have our eyes examined from time to time, especially if we are subject to headaches. ”

“ Sometimes wild hairs and skin disease affect the eyes. Eye strain should be removed by wearing well-fitting glasses and then these other conditions will disappear. If constant headache is experienced or the eyes itch or become tired easily, there is possibly eye strain. ”

“ If this little muscle is worked too hard, as when we try to read in a bad light, it becomes tired and we get what is called "eye-strain"; and if the strain be kept up too long, it will give us headache and may even make us sick at the stomach. The commonest cases of eye-strain are in eyes that are too flat (hyperopic) where this little muscle has to "bulge" the lens enough to make good the defect and bring the rays to a focus. ”

“ By a curious paradox, however, it often happens that the headache due to eye-strain is caused not by the grosser defects, such as interfere with vision so seriously as absolutely to demand the wearing of glasses to see decently, but from slighter and more irregular degrees and kinds of misshapenness in the eye, most of which fall under the well-known heading of astigmatism. ”

“ Mental strain may produce many different kinds of eyestrain. According to the statement of most authorities there is only one kind of eyestrain, an indefinite thing resulting from so-called overuse of the eyes, or an effort to overcome a wrong shape of the eyeball. It can be demonstrated, however, that there is not only a different strain for each different error of refraction, but a different strain for most abnormal conditions of the eye. ”

“ This strain, when it is habitual, leads to all sorts of abnormal conditions and is, in fact, at the bottom of most eye troubles, both functional and organic. The discomfort and pain may be absent, however, in the chronic condition, and it is an encouraging symptom when the patient begins to experience them.
When the eye possesses central fixation it not only possesses perfect sight, but it is perfectly at rest and can be used indefinitely without fatigue. It is open and quiet; no nervous movements are observable; and when it regards a point at the distance the visual axes are parallel. ”

“ Weakness of these muscles or insufficiency, especially of those required to direct the eyes inward for near work, may lead to symptoms of eye-strain. When reading, for example, the muscles which pull the eye inward soon grow tired and relax, allowing the opposing muscles to pull the eye outward so that the eyes are no longer directed toward a common point, and two images may be perceived or, more frequently, they become fused together producing a general blurring on the page. ”

“ But the vast majority of persons who wear glasses, both for the distance and for the near, can see quite as well without them. They do not wear them in order to be able to see, but in order to have the strain removed from their eyes, and to be relieved from the many disagreeable symptoms, both direct and reflex, that result from eye strain. ”

“ A complete cure of her condition was brought about within a week, and now, after the expiration of six months, there has been no return of her symptoms.
For the benefit of physician readers I should like to add that in treating eye strain, conjunctivitis, sties, granulated lids, and eye conditions generally, pressures made with a blunt probe, (see E Fig. 11) on the muco-cutaneous margins (where the skin joins the mucous membrane in the nostrils) affects the second division of the ophthalmic nerve, and assists materially in bringing about a favorable influence in eye troubles. ”

“ Through the tax made upon the nervous system by the eyes, there may be left an insufficient amount of nervous energy for the proper running of the vital processes. As a result there is a decline of the health. Ample proof that eye strain interferes with the vital processes and causes ill health, is found in the improvements that result when, by means of glasses, this is relieved. ”

“ The cause of this loss of function in the center of sight is mental strain; and as all abnormal conditions of the eyes, organic as well as functional, are accompanied by mental strain, all such conditions must necessarily be accompanied by loss of central fixation. When the mind is under a strain the eye usually goes more or less blind. The center of sight goes blind first, partially or completely, according to the degree of the strain, and if the strain is great enough the whole or the greater part of the retina may be involved. ”

“ VOLUNTARY PRODUCTION OF EYE TENSION A SAFEGUARD AGAINST GLAUCOMA It is a good thing to know how to increase the tension of the eyeball voluntarily, as this enables one to avoid not only the strain that produces glaucoma, but other kinds of strain also. ”

“ Numerous answers to this question have been proposed, but no one has yet succeeded in finding a satisfactory one.1 In the case of children it has been assumed by many authorities that, since the coats of the eye are softer in youth than in later years, they are unable to withstand a supposed intraocular tension produced by near work. When other errors of refraction, such as hypermetropia and astigmatism, believed to be congenital, were present, it has been supposed that the accommodative struggle for distinct vision produced irritation and strain which encouraged the production of short sight. ”

“ IT has been demonstrated in thousands of cases that all abnormal action of the external muscles of the ; eyeball is accompanied by a strain or effort to see, and that with the relief of this strain the action of the muscles becomes normal and all errors of refraction disappear. The eye may be blind, it may be suffering from atrophy of the optic nerve, from cataract, or disease of the retina; but so long as it does not try to see, the external muscles act normally and there is no error of refraction. ”

“ But human beings are often called to still greater trials—to total loss of sight—in other words, to perfect blindness. This calamity results from many causes; for example, the cornea may become so opaque as to be incapable of transmitting rays of light into the interior chamber of the eye; or the crystalline lens, also, may become opaque (cataract;) disease of the iris, attended by closure of the pupil, will produce blindness, as will also paralysis, or loss of energy, in the retina or optic nerve, (Amaurosis or Gutta serena.) ”

“ It is known as interstitial keratitis, and takes the form of a gradual, slow clouding of the clear, transparent convex surface of the eyeball, the cornea, through which the light passes to reach the lens. While the process is active, the child is made miserable by an extreme sensitiveness to light, the eye is reddened, and there is pain and a burning sensation. When the condition passes off, the child may scarcely be able to distinguish light from dark, to say nothing of reading, finding its way about, or doing fine work. ”

“ 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. ”

“ In a few hours violent inflammation supervened, and continued several weeks, in spite of the most vigorous and energetic treatment, its principal seat being the optic nerve, and subsequently the iris. The inflammation was at length overcome, but vision was not restored; and the irritability in both eyes was so great as to render it absolutely necessary not only to avoid all attempts to use them, but also to exclude them from the light. The sight of the right eye was entirely, and, as I feared, irrecoverably gone; its pupil contracted almost to the size of a pin's point, and immoveable. ”

“ When the eye is inflamed, great light becomes eminently painful, owing to the increased irritative motions of the retina, and the consequent increased sensation. Thus when the eye is dazzled with sudden light, the pain is not owing to the motion of the iris; for it is the contraction of the iris, which relieves the pain from sudden light; but to the too violent contractions of the moving fibres, which constitute the extremities of the optic nerve. ”

“ When inflammation has gone on in the eyelid, little knots like pin-heads form, producing a feeling as if sand were in the eye. Afterwards these knots grow large and swell the eyelid, and at times the matter in them grows hard, and seems to take up a lasting abode in that tissue. Strong and destructive liquids or powders are sometimes applied, that so affect the whole substance of the eye as to cause blindness. Nothing of this nature is required at all. First, the skin of the head must be dealt with. ”

“ When we use the eye too long, or in too bright a light, it becomes bloodshot. The increased action of its vessels and nerves gives rise to a sensation of fatigue and pain, requiring us to desist. If we relieve the eye, the irritation gradually subsides and the healthy state returns. But, if we continue to look intently, or resume our employment before the eye has regained its natural state by repose, the irritation at last becomes permanent, and disease, followed by weakness of vision, or even blindness, may ensue. ”

“ In September, when I first saw him, his left eye was very much diminished in size, and the cornea studded with white spots; the vision very imperfect, and constantly discharging water. The right eye was so opaque that neither iris nor pupil was to be seen, and he could only see the shadow of an object. ”

“ Symptoms.—More or less severe pain in the eye, forehead and temple, worse in the night and early morning especially. There is fear of the light and the eyes water very much. The sight is affected and there may be some fever. On examination the lids are found swollen and red, the eyeball shows congestion in the cornea and ciliary body, with some congestion of the conjunctiva. The cornea looks hazy. The anterior surface of the iris looks muddy and does not look so fine and delicate. The pupil is small and the light does not make it contract readily. ”

“ Healthy eyes even should never be used to read fine print or by a dim light. Serious injury may be caused by an imprudence of this kind. Reading upon the cars is also a fruitful source of harm. The lens, striving to adapt itself to the incessantly varying distance of the page, soon becomes wearied. Whenever the eyes begin to ache, it is a warning that they are being overtaxed and need rest.
Objects that get into the eye should be removed before they cause inflammation; rubbing in the meantime only irritates and increases the sensitiveness. ”

“ A characteristic of this condition is increase of the intra-ocular tension, which has a deleterious effect on the optic nerve end and its ramifications in the retina. The cause of the rise of tension is partly congestive, partly mechanical. The effect of glaucoma, when untreated, is to cause ever-increasing loss of sight, although the time occupied by the process before it leads to complete blindness varies within such extraordinary wide limits as from a few hours to many years. ”

“ DISEASES OF THE EYES Albugo, or Spot in the Eye, Opacity of the Cornea In consequence of a blow, stroke of a whip, or similar injury, an inflammatory action is set up in the eye, the result of which is an effusion of serum between the lamina of the outer coating of the eye, which renders the cornea or clear part of the eye, whitish or opaque in spots, interfering materially with the sight and usefulness of the organ. ”

“ Then the pupil may be dilated, and frequently its margin loses its regular, ovoid outline and becomes uneven by reason of the adhesions which it has contracted with the capsule of the lens, through its inflammatory exudations. In the case of excessive effusion into the globe of the eye that is found to have become tense and hard so that it can not be indented with the tip of the finger, paralysis of the retina is liable to result. With such paralysis of the retina, vision is heavily clouded or entirely lost ”

“ Sometimes, however, the eye alone is diseased: at least, the pathological state which it presents is unattended by any symptoms indicating an affection of the brain or its membranes. Many libertines present only an irritation of the conjunctiva and of the edge of the eyelids. It is a sort of chronic ophthalmia; their eyes are red, watery, fatigued, painful; and they cannot engage in the evening in any occupation, such as reading, which requires the attention to be confined to one object. ”

“ A still more serious effect, however, is the impairment of the vision of the affected eye, which, never entirely absent, sometimes amounts nearly to a total loss, from the insensibility of the retina, which is sometimes as complete as in confirmed amaurosis. In another series of cases the person is myopic, or sees objects only at a short distance. In some instances, again, there is double vision, or objects appear indistinct, and run as it were into each other, the image painted on the retina being confused and imperfect. ”