The limits of the card test must be constantly kept in mind: (1) it does not register eye sickness due to dust, smoke, or disease germs; (2) it does not show unconscious eye strain due to successful accommodation. But it will discover a great part of the children who most need care. Sooner or later, too, inflammation of the eyelids, due to external causes, will affect the nerves of the eye and their power to conceal by accommodation the eye's defects. Just as we unconsciously open the mouth when a cold stops up the nose, the eye adapts itself to our needs without our realizing it. We expect it to see. It sees. If our eyes are not made alike, they do their best to work together. Like a good team of horses, the slow one hurries, the fast one holds back a little. But if one eye is 10/15 and the other 10/10, they will both be unnatural and strained if both read the same type. The effects of this strain frequently upset the stomach before the eyes rebel. I learned that I needed eyeglasses after a case of protracted indigestion, first diagnosed as "nervous" and later traced to eyes. Thousands of upper-grade children and college students are dieting for stomach trouble that will last until the eyes are relieved of the undue and unrecognized strain. To prove the influence of eye strain on indigestion, persuade some obstinate parent to wear improperly focused glasses for a day; she will then be willing to have her child's eyes attended to.
It is unfortunate that the eyes will overwork without protesting. For years many persons suffer without learning that their eyes are unlike, or, as often happens, that one eye does all the close range work. Even when being tested, eyes will seem to see easily what requires a great effort of "accommodation." To prevent this self-deception skilled oculists do not trust the eye card, but put a drug in the eye that benumbs the muscles of accommodation. They cannot contract or expand if they want to. The oculist then studies the length of the eye and the muscle of accommodation. With this absolute knowledge of how each eye is made he knows what is wrong, exactly at what angle light enters the eye, whether objects are focused too soon or too late, exactly what kind of eyeglasses or what operation upon the eye is needed to enable it to do its work without undue straining or accommodation. So unconsciously do the eyes accommodate themselves to the work expected of them that not infrequently a child with seemingly perfect sight may be more in need of glasses than the child with imperfect sight. Practically, however, it is out of the question at the present time to have the majority of children given a more thorough test than that provided by the Snellen card. Where eye strains escape this test teachers will find evidence in complaints of headache, nervousness, sick stomach, chorea, or even epilepsy. The constant strain may also cause red or inflamed lids. Parents and teachers must be on the constant lookout for these symptoms of good sight persisting in spite of imperfect eyes.
An epidemic of eyeglasses is usually the consequence of eye tests. So naturally do we associate eyeglasses with eye defects that some people assert that the eye tests at school originate with opticians more intent upon selling spectacles than upon helping children. In fact, even among educators who proclaim the need for eye tests there has been far more talk of eyeglasses than of removable conditions that cause eye strain. The women principals of New York City have sounded an alarm, and urge more attention to light and to reading position, more rest, more play, more hand work, less home study and less eye work at school, rather than more eyeglasses to conceal temporarily the effect of abusing children's eyes. Putting glasses on children without changing causal conditions is like giving alcohol to consumptives. The feeling of relief is deceptive. The trouble grows worse.
For some time to come eye tests will find eye troubles by the wholesale in every industrial and social class, in country as well as city schools. In 415 New York villages 48.7 per cent of school children had defects of vision,—this without testing children under seven,—while 11.3 per cent had sore eyes.
There are three possible ways of remedying defects: (1) changing the eye by operation; (2) changing the light as it enters the eye by eyeglasses; (3) decreasing the demands made upon the eye. To change eyes or light requires a technical skill which few physicians as yet possess. It will be remembered that it is but thirty years since the medical profession in America first began to understand the relation of eye defects to other defects. Until a generation of physicians has been trained by medical colleges to learn the facts about the eye and to apply scientific remedies, it is especially necessary that teachers and parents reduce the demands made upon children's eyes; oral can be substituted for written work, manual for optical work, relaxed and natural movement for discipline, outdoor exercise for less home study. Other requirements are suitable light and proper position, and abolition of shiny paper, shiny blackboard, and fine print. Even after it is easy to obtain the correction of eye defects it will still be necessary to adapt the demands upon children's eyes to the strength and shape of those eyes. Because we are born farsighted, nearsighted, and astigmatic, we must be watchful to eradicate conditions that aggravate these troubles. Finally, there is no excuse whatever for permitting the parent of any school child in the United States to remain ignorant of the fact that it is just as absurd to go to the druggist or jeweler for eyeglasses as to the hardware store for false teeth.