Reading an eye chart mounted or projected on a wall is a standard part of every visit to the optometrist today, but it wasn't always that way. Centuries ago, practitioners struggled to measure vis ...View Article
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Posted on 08-05-2013
Most people think of 20/20 when they hear the word vision. Most eye doctors spend most of their time helping people see the 20/20 line on the eye chart. Once it is determined that the eyes are healthy most eye doctors are interested in little else. You may not realize this but 20/20 is nothing more than average eyesight. It is the ability to see a certain size letter at a certain distance. Some people can see better than 20/20, some cannot see 20/20 even with what are referred to as “corrective lenses.”
The lenses we know as corrective are really not corrective at all. They are actually compensating lenses. They do little more than mask an outward symptom – the inability to see clearly at some distance. These compensating lenses ignore any underlying reasons for the symptom they cover up.
There is much more to vision than just seeing clearly. That is why I avoid the word vision and use visual process in most of my communications with people. The visual process is a dynamic process that occurs in the brain, not in the eye. The retina (the inner back surface of the eye, which processes light) is in fact part of the brain. The visual process develops, and continues to do so throughout our lives. The primary purpose of the visual process is to direct action. The visual process is learned and therefore trainable at any age. People can also experience visual difficulties at any age. Behavioral optometrists are trained to analyze, diagnose and treat every type of functional visual problem.
So there should be much more to an eye exam that just trying to see smaller letters across the room. Behavioral optometrists evaluate much more than that. Behavioral optometrists evaluate the ability to smoothly and accurately track a moving target and how efficiently a person is able to shift their eyes from one target to another. That is why what behavioral optometrists do is not an eye exam, but a visual evaluation.
Vision, or something akin to it has evolved from some of the simplest creatures in the history of our planet, all the way up to what some consider the most highly evolved, most intelligent creatures in our planet’s history – dolphins, I mean human beings. Different creatures have different types of eyes for different reasons. Different types of eyes provide different types of advantages. For example, flies have compound eyes to provide maximum awareness of their surroundings to avoid being swatted by creatures that have, to their way of thinking inferior, simple eyes. However, I don’t think that, even if they were able to reach the gas pedal, their compound eyes would ever enable them to operate a motor vehicle. Those compound eyes provide a very different visual experience from our simple eyes. Other creatures, like lizards, have eyes on the sides of their heads to give them the ability to keep track of more of their surroundings.
Some creatures have their eyes stuck right on the front of their face, pointing straight ahead. The greatest advantage provided by this arrangement is the ability to judge space and depth with a great deal of precision. This was initially helpful in tracking and catching moving prey. Now it is also helpful for copying from the board, running without slamming into the door frame, hitting a baseball, shooting a basket, driving a car without hitting other cars, parallel parking and many other things we do every day.
It is much easier to gauge speed, direction of movement and distances with the type of visual equipment we humans have. The visual process provides not only information, but is the guidance system we use to direct all of our actions. In fact, as was previously stated, the primary purpose of the visual process is to direct action, everything else is secondary at best.
Nowhere in creation have eyes evolved for the task of reading, nor for staring endlessly at a computer screen, iPad or smart phone. There are two important factors that make these tasks stressful for a visual system that is designed as ours is. First, these activities are two-dimensional. Second, they involve very little movement other than a few fingers or thumbs flitting around a keyboard, or lips moving to read a few difficult passages. For a visual system designed for action and three-dimensional seeing, the constant, prolonged encounter with a two-dimensional surface is like walking into a brick wall. We are all happier to be able to walk around in any direction we would like. Walking straight into a solid wall for hours on end, day after day would cause not only extreme boredom, but severe frustration, stress and fatigue. This is similar to what is happening to our visual systems when we subject them to prolonged exposure to two-dimensional tasks.
Prolonged visual tasks without movement present a similarly undesirable situation. It turns out our eyes are in constant motion. If not for the fact of these constant microscopic eye movements, we would not see. Period. Experiments have been done that simulated a situation where the eyes were perfectly still. They showed that if an image was projected to the exact same spot on the back of the eye it would fade from conscious awareness in a matter of seconds. This constant wiggling of the eyes keeps this from happening. The point here is that, from the bottom up, from input to output, the visual process is intimately involved with movement. However, we are more concerned here with movement of the body. Our visual systems are best suited to activities that involve our moving around in some way.
I hope you can see that the visual process is so much more than just sitting in a chair reading letters on a wall. It is complex, elegant and pervasive in human behavior. Don’t settle for an eye exam; have your visual process evaluated as soon as possible. All children should receive a thorough visual evaluation before entering school because most visual problems go undetected without the input from a behavioral optometrist.
Next time: My Story. I’m not just another eye doctor – I once was a regular person visiting eye doctors, just like you. I’ve had many visits to many eye doctors over the years. Tune in next time for the exciting story.
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