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.
Good eye health with a balanced binocular visual system are both important in providing a
lifetime of clear, comfortable vision. The need for good eye care starts in childhood and
continues to the end of our lives. It has very little to do with "but I just wear the glasses
for driving" or "I only need glasses for reading." Give your eyes the appropriate attention they
deserve so that you can continue to enjoy this treasure called sight.
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.
There is another very common misunderstanding about a term referred to as “legally blind.” When
people who have very large prescriptions don’t wear their glasses/contact lenses, there acuity is
very poor and they will sometimes say that they are legally blind. This is not true. The
term “legally blind” refers to someone who even when wearing their best prescription still has
very poor vision. This is usually due to birth defect, disease or trauma. Since even with the
best prescription their vision is very poor, it is very difficult for them to function in our society.
The designation of “legal blindness” will now entitle this person for some help from the state.