The Human Eye and Motoring

SEPTEMBER, 1935. ARIZONA HIGHWAYS 11 The Human Eye and Motoring

(Editor's note: This is the second of a series of articles on the human eye as related to safe motor travel.) THE human eye as we know it today is the result of a period of evolution covering hundreds of thousands of years. Mankind has lived on earth for at least one hundred thousand years and up to fifty thousand years ago man was still largely uncivilized and only in the past four or five thousand years has he used written symbols to any extent. In fact only in the past half century have printed matter and artificial lighting been in widespread use.

For at least ninety-nine percent of the time man has lived on earth he has lived an outdoor existence. His eyes are adapted for outdoor seeing at long distances by daylight under the shade of trees, and with the forest carpet as a floor. His only use for near seeing has been to tie a few skins together, or peel a banana or sharpen a piece of stone.

Life depended upon his ability to see distant objects clearly. To study them critically at arm's length was relatively unimportant and this he did casually and only occasionally. It might have been far better for the eyes of the nation, had man not changed all this, and built his artificial world, for he has moved indoors, and in the dim light of his own making, dim compared to the light of the sun, he began using his eyes and abusing his eyes so that we now have one out of five children coming out of grammar school with some eye defect (twenty percent), of those children who go on to college, forty percent have defective vision, among adults from forty to sixty years of age sixty percent have some visual defect and ninety-five percent of the adults over sixty years of age do not have good vision.

But man is not going to hunt buffalo or stalk his prey down the woodland paths, as did those who came before him. His eyes are called upon to do many tasks for which they have not sufficiently developed. Evolution is a very slow process but just as surely as the human eye has developed to its present highly perfected state during the past thousands of years, so may we be sure that continued development will bring about eyes better adapted to the work required of them.

Modern Living Conditions Prove Real Test for Optics By DR. R. E. SOLOSTH

The great difficulty facing most persons today is that of making an outdoor eye do inside work at nearer distances and under poor illumination. Most eyes give trouble sooner or later under modern living conditions. Herein lies the secret of Johnny being able to play in the open for hours without apparent trouble, yet he is hopelessly unable to get his lessons. Mr. Jones is able to play golf, or work in the out of doors, but the thought of reading or doing that bit of book work, which he has let slide for days, almost gives him a headache, for he knows he will have one if he does do it. This is now a "near point world". The seeing of far horizons clearly, is not the dread demand. That day is past, the boy or girl, just entering the grades, or high school or proudly entering the great school of experience, the employee for the first time accepted by the ripe judgment of the older business man, is not going to stalk his prey on the hills, his duty will be close at hand, on a desk, at a blackboard, at most, a few feet away, he must use his eyes to suit his needs. The power to concentrate at near is the test of fitness, and visual efficiency.

The motorist who attempts to look out over the horizon to left or right finds himself in the ditch, for automobiles have no eyes, yet a large percentage of their drivers cannot see well enough to avoid accidents, as is clearly shown by our daily mounting toll of human life and destruction of property. When the driver's eyesight is imperfect his automobile is a menace to both pedestrians, and other drivers, for the guidance of a mass of machinery weighing from one to many tons, depends upon the eyesight of the man at the wheel, and these twentieth century, high powered machines are often operated by a human element dating back to the Victorian age whether he possesses clear, keen vision. The Hyperope, or far sighted person is at once found to consist of two types, the first of these, is the person who possesses an error in his visual function, but can overcome this error and sees to his satisfaction for both near and distance, since he has no idea of what good, comfortable sight would consist. He may maintain vision, however, at great expense to his general nervous system, for we know that the normal eyes use about fifteen percent of the nervous energy of the entire body, abnormal eyes, from twenty to fifty percent, first borrowing from the stomach and heart which slowly does its deadly work like worms eating at the roots of a tree, until symptoms manifest themselves such as painful vision, intolerability to strong light, headache, indigestion, sleepiness, dizziness, twitching, squinting, seeing double, burning and feeling as if sand were in the eyes. The second, the far sighted person who cannot overcome his error, or who can no longer borrow from other functions of the body, and finally is forced to resort to artificial means. Many people who fall in this general type boast that they see clearly because they see a distant mountain, but they do not possess really accurate sight.

Objects of small size and often very close at hand, are in great danger of being hit, run over and seriously injured, by swiftly moving vehicles, passing at a rate of speed which makes it impossible for the observer to comprehend their nearness, before enough time has elapsed to maintain the margin of safety, for eyes require time to see. In normal eyes about one-sixteenth second elapses between the time the object is looked at and the time it is finally interpreted by the brain. Moderately defective eyes may require as much as half second for seeing, but much longer time than this would be required by a person who has less than half of normal vision.

It is clear then, that an automobile proceeding down the highway at forty miles per hour with a person at the wheel who sees even moderately well, his speed is approximately sixty feet per second, and if it takes him one-half second to see that he is in danger, he has gone thirty feet farther toward destruction before he is able to act, the (Continued on page 22) There are several general types of defective vision, which can be determined by quick tests, to the satisfaction other car has also approached at perof the average individual, to prove