Good Eyesight = 20/20 ??
Having good eyesight is definitely more than being able to see all the tiny letters on the eye chart at twenty feet and sixteen inches. For example, the vision test using eye chart does not check your flexibility to see clearly when changing viewing distances or when maintaining focus at the same distance for longer periods of time.
Ciliary muscles are the important muscles in our eyes. These muscles relax when we look far away and contract when we look up close.
If our eyes are like cameras, then the ciliary muscles are the key to focusing the camera lenses. It's not enough, however, to be able to keep the camera focused clearly for the few seconds that it requires to capture a line of six or eight letters on an acuity chart.
To have good eyesight, we requires four different skills:
1) the accuracy to see tiny letters,
2) the power to see up close,
3) the flexibility to change focus from far to near or near to far, and
4) the endurance to see clearly for longer periods of time.
Let's look at each of these four skills separately.
Accuracy The 1st Key to Good Eyesight
The size of the letters we can see on the eye chart gives us a good indication of the accuracy of our ciliary muscles.
Surprisingly, we do not need to focus our Ciliary muscles perfectly to see the 20/20 letters, because 20/20 eyesight-despite its reputation-is far from perfect. Letters as large as the 20/20 letters gives our Ciliary muscles some leeway-even if we tighten the muscles in our eyes too much, or not enough, we can still make out the letters during an eye test.
It is common to find both children and adults who complain of "blurred vision" despite measuring "good eyesight" of 20/20. On the other hand, seeing the 20/10 letters (letters that are only half the size of the 20/20 letters) requires complete accuracy of our Ciliary muscles. If those muscles fail to contract exactly the right amount, we cannot see letters as small as the 20/10 letters.
Power The 2nd Key to Good Eyesight
We determine the power of our Ciliary muscles by measuring how close we can see tiny letters.
Most fifteen-year-olds with the normal use of their eyes have the power to see tiny letters as close as three or four inches. From the teens on, however, that power begins to wane. Due to the normal aging process, sometime in our thirties we lose half of our Ciliary power and our near focus goes from four inches to eight inches. Over the next decade, we lose half our power again, and our focus creeps out to sixteen inches. The next time we lose half our eyesight power -usually between the ages of forty and forty-five-our focus jumps out to thirty-two inches and suddenly our arms are too short to allow us to read.
Although a number of the patients claimed that the problem was with their arms rather than their eyes, all have preferred reading glasses to the prospect of having their arms surgically lengthened until their knuckles dragged on the ground.
Those with mature eyes, however, are not the only ones whose Ciliary muscles need a boost of power. Occasionally young adults or even children who lack the vision power also need to read or study without fatigue.
To get an immediate idea of your own eyesight power, cover an eye with one hand and move the Near Testing Eye Chart as close as you can and still make out the letters in the 40 line. Change eyes and repeat the process. If you wear reading glasses, wear them for this self-test. After you've done your eye exercises for two weeks, recheck your eye power in the same way and see if there has been a change.
Flexibility The 3rd Key to Good Eyesight
Those who see things blur when they first look up from their books or computers are experiencing difficulty with the flexibility of their Ciliary muscles.
If your hobbies or job requires you to shift focus from one distance to another, and this shifting isn't almost instantaneous, then you're probably throwing away hours waiting for things to clear. For example, the student who takes longer than others to shift focus between the chalkboard at the front of the room and the notebook on her desk will take longer to complete work that's written on the board.
Endurance The 4th Key to Good Eyesight
As I mentioned above, it's not enough to be able to call out half a dozen letters on an eye chart and conclude that you have good eyesight.
You have to be able to maintain that clarity over time even if you can read 20/10. Those who have trouble with eyesight endurance have trouble sustaining vision while reading or driving. Commonly, they experience blurred vision, sore eyes, and even headaches when using their eyes for extended, careful seeing. The ease with which you can perform the eye exercises described in the second half of this chapter will give you a good idea about both your eyesight flexibility and endurance.
20/20 vision is a good starting place towards attaining good eyesight, but ONLY a starting place. Having 20/20 eyesight doesn't guarantee that we can keep the print effortlessly clear when reading. Having 20/20 eyesight doesn't guarantee that things are clear in the distance when we first look up from a book or computer monitor, or that we don't suffer from headaches or upset stomachs when we read. Having 20/20 eyesight doesn't guarantee that we can read street signs at night or see as well as those around us.
At the very best, all that 20/20 eyesight guarantees is that we can stand twenty feet away from a nineteenth-century eye chart and keep things clear long enough to read six or maybe eight letters.
"So," you may ask yourself, "why settle for 20/20 eyesight?" My answer is, of course, "Yes, why?"
Why settle for sore eyes or headaches during computer work? Why settle for the extra effort that silently fatigues us when we read and leaves us worn out by day's end? Why settle for straining to see street signs during night driving? Shouldn't that Civil War eye chart have been buried in Arlington Cemetery well before the close of the twentieth century? In short, why settle for cotton-gin seeing during the age of the Internet?
Well, if you're ready to bring your visual fitness into the twenty-first century, then it's time to begin by learning to flex your Ciliary muscles for .
Before starting, however, let me caution you: Like any other exercises, putting these muscles through their paces may initially cause some aches and pains. Your eyes may tug and burn. You may feel vaguely headachy. Even your stomach may protest because the same involuntary system of nerves that controls your focusing also controls your stomach. If, however, you hang in there and continue putting in your seven minutes per day (three and a half minutes per eye) to attain good eyesight, the aches and pains you experience will gradually disappear, not only when you do your exercises, but all day long, whenever you use your eyes.
Accuracy. Power. Flexibility. Endurance.
These are, after all, what Good Eyesight is about!
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