Even if you don't wear eyeglasses or are not interested in contact lenses, I think that you will find this information about good eye health and balanced binocular vision both interesting and important.

How valuable is your vision to you? What price tag would you hang on your eyes? Surveys indicate that over 80% of the people feel that blindness is the worst thing they could be forced to experience. When you awoke today and opened your eyes, did you give a thought to the fact that you could see? Could you even imagine what your life would be like without the benefit of vision? If our vision is so valuable to us, why is the average time in this country five years between exams? How long has it been for you?

"But I see fine. Why should I have my eyes checked?" I hear this all the time. Unfortunately good vision does not ensure that you have healthy eyes. In fact, the most serious, blinding conditions do not affect vision at all until they have done irreparable damage. Although there are many such conditions, two of the most common are glaucoma and diabetes. Indeed, diabetes is the leading cause of permanent vision loss in this country for people under fifty-five years of age. Both glaucoma and diabetes do irreversible damage to the eyes and both can be without noticeable symptoms. "I would know if I were going blind" is what I hear people tell me. Let me repeat this very important message - there can be NO SYMPTOMS! There is no pain, and vision can remain clear until near the very end, when the diseases have run their course and blinded the eyes. The only way to check for these conditions is through a comprehensive eye examination. Prompt diagnosis and treatment are necessary to provide the best possible chance for a lifetime of good, functional vision.

Even if your eyes are healthy and disease-free, balanced binocular vision is important to how you see. You may be asking yourself, "What is balanced binocular vision and why would it be important if I already see well?" Binocular vision refers to the two eyes working together as a team. Imagine trying to run a race with one leg in a cast or significantly shorter than the other. You would be at a significant disadvantage due to the lack of teamwork of the legs. The same is true of the eyes and their ability to cooperate as a team. In the case of the eyes, lack of balanced binocular vision can result in eye fatigue, difficulty with detailed tasks such as reading small print or working on the computer, words moving or floating off the page while reading, lack of concentration or reading comprehension, double vision, headaches or browache. You might even consciously or subconsciously avoid certain tasks that would lead to any of these symptoms. Both children and adults can be affected.

Children's eyes change all the time and they can often experience rapid prescription changes. Children are also very adaptable and so typically do not complain of any vision problems. Unfortunately, I often don't see children for their first eye examination until the teacher has already noticed that the child is having a problem. It may be a prescription problem, binocular vision problem, or a combination. Occasionally, it can also be an eye health problem. Most of what we learn is through our eyes. Children that do not have the benefit of a smoothly functioning visual system are at a disadvantage in school. Let's not forget to give our kids the proper tools so that they may excel in their studies.

So What Does 20/20 Really Mean?

There is almost nothing related to vision that has more misunderstanding surrounding it than the ratio 20/20, and what it really means. Do you believe that if you have 20/20 vision that your vision is perfect? Many people believe this to be the case. 20/20 is a measurement of something called “acuity” and this “Snellen” ratio is only one of many ways to measure acuity.

Visual acuity is a description of just how sharp something is seen. There are at least half of a dozen of relatively common measurements of acuity. Snellen acuity is certainly the most commonly used measurement system for the general public. The Snellen system uses the very familiar 20/20, 20/40, 20/100, etc. notations. What do these numbers actually mean?

The top number is the actual distance in feet that is being tested. If the top number is 20 then the person being tested is having their vision checked at 20 feet. The bottom number is the distance in feet that an “average” eye can see a letter of that size. For example, if the bottom number is 100, that means that an “average” eye would be able to see that letter at 100 feet. If you have to be 20 feet away from that letter instead of 100 feet away, your visual acuity is 20/100.

The size of the letters being tested are based on what has been determined to be average for healthy eyes. For those of you who are interested, it has been shown that an average healthy eye should be able to read a letter 8.84 millimeters high at a distance of 20 feet. When we test you at 20 feet and you can read a letter of this size you are said to have 20/20 vision. If your vision is not as sharp as 20/20, the bottom number would get larger such as 20/200. Vision can be better than 20/20 also. If your Snellen acuity was 20/15 for example, you would be able to see a letter at 20 feet that a average eye would only be able to see at 15 feet.

You can see that 20/20 does not really have anything to do with perfect vision. Additionally, and much to many peoples surprise, the amount of prescription that you have does not determine how sharply you can see. When wearing your proper prescription your acuity will be at its very best. You may wear a very large prescription but be able to see 20/15. You also may not need very much prescription yet still only have the acuity of 20/25. How sharp you can see is dependant on factors other than how much prescription you need. Obviously, if you need a prescription and are not wearing it, your acuity will be decreased.