should be done. There are three things that every healthy eye does: Blink, center its attention (called Central Fixation) and shift.
1. Blinking, the first habit of normal sight an involuntary action. The blink is the quick, light, easy closing and opening of the eye, and it is done intermittently by every normal eye. The rate of blinking varies with people and also varies with the use an eye is put to. You blink more, for instance, when you look at something brilliant than you do when you look at something soft in tone.
a. Frequently the dividing point between a normal and abnormal pair of eyes is its impulse to blink under a given situation. If the eyes are perfectly normal, they will blink; suppression of the act of blinking shows a tendency to become abnormal.
b. The action of the eyelids in blinking is most essential to normal eyes and sight. The fluid that keeps the eyes moist is produced by a small gland called the lacrimal gland under the outer portion of the upper lid. When one blinks, this fluid is washed down and over the eyeball and keeps the eye moist.
This moisture has several functions:
(1) There is a definite antiseptic and cleansing action of the fluid.
(2) The brilliance of the eyes and their ability to reflect light are largely due to the fluid on their surface.
(3) The fluid is essential to the cornea, which is the small translucent front part of the eye. Since the cornea has no blood vessels, it needs this fluid to keep it moist or it may develop corneal ulcers.
(4) When particles of foreign matter get into the eye, the lacrimal fluid tends to float them off, while on an eye that is dry, the particles may stick and imbed themselves.
(5) In cold weather, frequent blinking tends to keep the eye warm. An eyeball can be very uncomfortable when cold.
(6) In strong wind or when the weather is very dry, blinking comforts and protects the eye. Under these conditions, one should blink frequently, almost continuously, because the fluid is lost so rapidly.
(7) In the short interval of blinking, the muscles of the pupil have a chance momentarily to relax their tension.
(8) Blinking also enables the eye to move slightly and thus allows the recti muscles to make the small amount of movement essential to their well-being, since motion is necessary to the health of any muscle.
(9) The circulation of the lymphatic fluid around the eye is aided by blinking, and the eye is strengthened by this good circulation, just as any body is benefitted by keeping the circulation of the blood active around it.
c. Blinking is not an interruption of continuous vision. Continuous vision is the illusion that a normal eye produces, authentic in effect but nevertheless an illusion. When an image falls on the retina, there is another image or an after-image produced. In other words, the image remains on the retina for a short period longer than the image is kept before the eye. It is as if your image in the mirror, stayed there a moment after you had gone away.
Thus, it is not necessary for the eye to be seeing actively all the time in order to produce the illusion of seeing constantly. In fact, nothing in the body works more than half time or so much as half time. More than half of the time of every organ is consumed in the repair and replacement of its own tissue and the elimination of its waste products.
d. The frequency of the visual impressions made by the eye is between thirty and forty images per second in the average person. Therefore the blink does not interfere with constant vision. It is possible for the eye to blink so frequently that the eye is closed half of the time and yet it will see as much as if it were open all the time.
e. In fact, blinking increases the actual amount of time you may actively see, since failing to blink constitutes strain and this may reduce the number of images from thirty or forty to twenty or fewer images per second. There is no single instance where blinking interferes with sight. It is a natural, constructive performance and improves the eye. If for some reason the eye has not been blinking normally, the resumption of normal blinking improves its vision.
f. Do not confuse a wink or a spasm of the eyelid with blinking. A spasm of the eye lid is a forceful, involuntary constriction of the lid and usually involves the muscles around the eye as well as the muscles of the eyelid and is frequently associated with some nervous disease. A blink is a light, easy, smooth, barely noticeable movement of the eyelid.
g. If you have formed a habit of looking too fixedly at things, remind yourself to blink. Blink consciously and often. Condition your reactions until you again have the unconscious blink.
2. Central fixation: The second habit of normal sight is to have the eye and the mind so coordinated that they fix on a small area at one and the same time. In other words, when you look at an object you should localize your attention, fasten it on the one small area, not scatter it.
a. For example, when you look at a page of print, you cannot see the whole page clearly. If you fix your eyes on the upper right-hand corner of the page, you can see that clearly, but the remainder of the page, although it is within your field of vision, is much less clear. To see the last word on the page clearly, you will have to shift your eyes so that they are directed straight at that word.
b. The same is true if you take words quite close to each other. To see the first word of a line clearly you must look directly at it, and to see the last word on that line it is necessary to shift the eye. The same is true if you want to see the second word on the line clearly. You can see it well enough to read it, but you do not see it perfectly clear when you are looking at the first word. A definite strain is involved if you try to see it that way. This is true down to the very smallest degree of space.
c. There is a basic, structural reason for this. The Macula Lutea, the only part of the eye that sees perfectly clear, is in the center of the retina and is no larger than the head of an ordinary steel pin. This dot of perfect sight is placed in the eye like a point at the bottom center of a bowl whose sides slope gently like an arena. This one tiny point has clear, strong vision. When your vision departs from that point, there is a tremendous reduction in clarity of sight. There is, instead, blurred, collateral vision. And this is increasingly blurred as you continue out from the center until near the outside edge there is only perception of general shape, color and motion.
d. Since only this point, the Macula Lutea, has perfectly clear vision, only a very small area can be seen clearly at one time. But the movement of shifting is so swift that the illusion of seeing a large area is given. The images falling on the Macula Lutea are carried swiftly into the visual brain centers, one succeeding another with such rapidity that there are thirty or forty and sometimes more images a second, thus creating the illusion of a whole picture in the brain.
e. This ability of the brain to carry successive images and so produce the illusion of clearly seeing the whole object or a considerable area is an impressive and beautiful fact, but it is also a cause of trouble to the shooter. One comes to believe that the eye itself can see a large area clearly, and so misuse slips in because any attempt to do this is to use the eye without focusing!
f. “Large Area” means trying to see for example, two words or more at a time.
The healthy, normal eye habitually sees only a very small area at given moment. The mind and the eye normally coordinate perfectly on each word or point of observation with no effort or impulse to see more, just as it does when one is writing.
If the practice of seeing a large area at one time persists over a sufficient length of time, the ability to focus perfectly is lost and the blurred vision naturally to the collateral area is the only vision possible. It is then necessary to retrain the eye and mind to look at only a small area in order to again have central fixation without which no vision can be clear and normal.
g. One can read indefinitely without undue tiring or harming the eyes in any way if the eyes are relaxed and the vision is localized. But, if the seeing power of the collateral field of vision is used, the eye is straining and there is a resulting fatigue and loss of efficiency.
The fact that the eye sees clearly only a very small area at any one time cannot be over stressed. In the awareness of this fact rests the coordinating of the mind with the structural limitations of the eye, without which there cannot be normal vision.
If you grasp this fact of focused vision and mentally close your sight to a large area, you will attain this valuable habit of central fixation and find increased efficiency in the use of your eyes in shooting.
3. Shifting. The third beneficial habit of normal eyes is to shift. This seems to quarrel with the second habit which is to localize your gaze but in reality it does not. You must point your gaze, but you must, too, constantly shift your point of vision.
