What is Vision?
Is "20/20" Really Enough?
What does your optometrist mean when he or she says you are seeing “20/20”? It means that when standing at a distance of 20 feet from the eye chart, you can see the same row of letters that the average person can see at this distance. If you have 20/50 vision, for example, it means that you must be as close as 20 feet to see what a person with normal vision can see at 50 feet. Visual acuity is often measured according to the size of letters viewed on a Snellen chart, which is a measure of the sharpness of sight. However, it does not tell you anything about how your brain is processing what you see.
The visual system is so complicated, it utilizes 65% of ALL our brain pathways. “20/20" eyesight represents only a very small part of this process.
In fact, there are over 20 different skills visual skills that an eye chart does not detect, abilities learned and developed from our experiences interacting with our environment since birth. Experience is vital to vision development.
It is important to differentiate between the terms “sight” and “vision”. “Sight” is the ability to see and the eye’s response to light shining into it. “Vision” is the ability to interpret and understand information that comes through the eyes.
Take the clear, though slightly overexposed, picture below. Are you able to tell what animal this is a picture of?
What if I said it was a cow?
Even though the picture is not blurry, without a framework to work within, it is often difficult to extract meaning from the picture. Once you are told it is a cow, now the eyes know what to look for.
(If you still have difficulty, try placing your mouse over the picture to show you an outline of the cow).
The visual system is a significant part of how we process information and a key factor in how we learn. 80% of what you perceive, comprehend and remember depends on the efficiency of the visual system.
A more comprehensive definition of vision is a dynamic process of identifying, organizing, interpreting and understanding what is seen. Vision is a process that integrates sensory and motor information generated by the brain and body to derive meaning and direct movement.
Vision is a learned skilled and developed over time, just like walking and talking. It is learned
over time from birth (and arguably earlier) on up by our experiences and how we react and solve problems.
The visual skills we learn early on provide the foundation for later
visual complexities. Any weak link in the visual process can affect the outcome,
especially if the visual system is under stress.
Think of having the right machine, such as a car, but not knowing
how to really use it. In order to make the car more useful, you have to figure out
how to coordinate all the levers, knobs and pedals. When you first learn, you concentrate more on the mechanics of driving a car rather than enjoying the ride. As it becomes more of an automatic skill, you get to the point where you can have a conversation, eat and navigate with ease. The visual process is much the same way.
You may have two eyes, but learning how to coordinate them together and interpret
the information coming in takes skill and practice. Individuals with an inefficient system tend to concentrate more on the mechanics of making it work. For individuals with efficient visual systems, these skills are automatic and they are free to concentrate on the task as hand, such as reading comprehension.
Basically, we use vision to guide motor behavior, like catch a
ball; interpret space and time, like when we give directions and say "it
will take 10 minutes if we turn left at the light coming up in two blocks"; store and recall visual information so you can do things like remember where your keys are because you can "see" them on the dresser; and integrate information from our other senses (hearing, touch, taste and smell) like when we see a picture of popcorn we can actually taste and smell popcorn. This allows us to think, understand and react to the world around us.
Vision allows us to take what we see and process this light information
so we can -
- Identify what we see by where it is,
how far away it is, how big it is, how fast it is moving, what texture it
- Store this current information for
- Integrate the sight information with
all our other senses - touch, hearing, taste and smell.
- Compare this information to previously
stored information in order to confirm prior experience or reconstruct a prior
experience if necessary.
- Derive meaning from both the new information
and past information.
- Decide the relationship between where
we are and where it is, or find out where we are in space.
- Act on this new meaning.
- Use this new perception to direct movement or thought.
Visual skills are important in academic performance.
Vision is there every step of the way when you learn and process
information. If vision does not develop efficiently, even a bright child can have difficulties with reading, writing, spelling and math. Getman, a renowned behavioral optometrist, stated,"Vision
is the dominant mode in the development of intelligence." The more efficient
a person is, the higher their score on many intelligence tests. This is why
IQ scores can change after vision remediation.
We gain the ability to understand and
interpret what we see correctly and efficiently as we integrate
and utilize the information we gather, learn from it and modify this information
by experience. If one or more of these skills are deficient, then the signal
through the visual pathway may not be as clear as it could be. This can cause
difficulty with learning or performing various tasks, such as reading.
One out of four children has a vision problem which interferes with their ability to learn efficiently and achieve in school.
Since 75-90% of classroom learning comes through
the visual system, poor visual skills can affect a child's performance. Why?
It takes more energy to use a faulty visual system than it does
an efficient one.
So why is it that some individuals fair better in school than others when they have similar visual inefficiencies? Think about the following analogy:
Having poor visual skills is like filling a glass of water using
a spoon with one or more holes in it. A child may know how to do the task set
before them and be a very physically and mentally capable child, but are not
able to do the task as well as the child sitting next to them with a regular
spoon. A very motivated child may still fill the glass full of water, but it
will take more time and effort than a child with a spoon without any holes.
Another child may become frustrated and give up or may fill some of the glass
every once in awhile if they have more energy that day. The problem is most
kids do not know they have a faulty spoon and neither do their parents or teachers.
Why do these children not get identified in school?
Most school screenings only check how clear a child sees in the distance. Unfortunately, most of the kids impacted by inefficient visual skills pass this type of school screening. The children who fail school screenings actually tend to be the high achievers in the classroom.
It is suggested that if you suspect ADD, you should also get a comprehensive vision evaluation.
Visual signs and symptoms often mirror Attention Deficit Disorder (ADD). In fact, 15 out of the 18 signs and symptoms used to diagnose ADD are the same as visual inefficiency problems.
For instance, if you have trouble with your visual focus, or actually making the words clear for a long period of time, it is more difficult to keep your attentional focus on them.
Vision Problems Can Be Remediated
Treatment for inefficient visual skills can be in the form of lenses, developmental guidance or an individualized vision therapy treatment program. Vision therapy re-organizes neural pathways by building new synapses, thereby affecting the patterning of the brain.
According to the California Department of Youth Authority, 70% of juvenile delinquents tested have vision problems affecting learning. When optometric vision therapy was performed on incarcerated youths, recidivism reduced from 45% to 16% at the Regional Youth Education Facility in San Bernardino, CA.
The best way to treat a problem is to prevent it before it occurs.
A developmental vision problem can be diagnosed during the pre-school years and can often be corrected before the child enters school, though it is never too late to treat. Children do not grow out of vision problems. Children with vision problems become adults with vision problems.
The Vision Council of America and the American Optometric Association recommends that children’s vision be examined before the age of 1, again at age 3 and 5 or before starting school. Thereafter, everyone should receive an annual exam.
Remember, not all eye care professionals emphasize the function of vision. You want to be tested for both “eyesight” and “vision” to determine not only eye health, how clear you see and if you need glasses, but how efficient your visual system is working. Ask your eyecare professional if they evaluate at least the following visual skills:
- Eye tracking (eye movement control)
- Focusing near to far
- Sustaining clear focus up close
- Eye Teaming Ability
- Depth Perception
- Visual Motor Integration
- Visual Form Perception
- Visual Memory
If your eye care professional does not evaluate the above skills, find a behavioral optometrist in your area who does. You can visit the College of Optometrists in Vision Development’s (COVD) website at www.covd.org.
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